)]}'
{
  "log": [
    {
      "commit": "f8b7fc6b514f34a51875dd48dff70d4d17a54f38",
      "tree": "dc6583851e3536516761b0fd9b07f5a3a1743ebb",
      "parents": [
        "a46e0899eec7a3069bcadd45dfba7bf67c6ed016"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Thu Jun 16 08:26:32 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Jun 16 16:12:05 2011 -0700"
      },
      "message": "rcu: Move RCU_BOOST #ifdefs to header file\n\nThe commit \"use softirq instead of kthreads except when RCU_BOOST\u003dy\"\njust applied #ifdef in place.  This commit is a cleanup that moves\nthe newly #ifdef\u0027ed code to the header file kernel/rcutree_plugin.h.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "a46e0899eec7a3069bcadd45dfba7bf67c6ed016",
      "tree": "78158b4056fe1365d5086f66769abdc3ef2643c3",
      "parents": [
        "09223371deac67d08ca0b70bd18787920284c967"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Jun 15 15:47:09 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Jun 15 23:07:21 2011 -0700"
      },
      "message": "rcu: use softirq instead of kthreads except when RCU_BOOST\u003dy\n\nThis patch #ifdefs RCU kthreads out of the kernel unless RCU_BOOST\u003dy,\nthus eliminating context-switch overhead if RCU priority boosting has\nnot been configured.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "09223371deac67d08ca0b70bd18787920284c967",
      "tree": "0ad0354a93ac209c8cfd2b79d03d0462aa3c5c58",
      "parents": [
        "9a432736904d386cda28b987b38ba14dae960ecc"
      ],
      "author": {
        "name": "Shaohua Li",
        "email": "shaohua.li@intel.com",
        "time": "Tue Jun 14 13:26:25 2011 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Jun 14 15:25:39 2011 -0700"
      },
      "message": "rcu: Use softirq to address performance regression\n\nCommit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread)\nintroduced performance regression. In an AIM7 test, this commit degraded\nperformance by about 40%.\n\nThe commit runs rcu callbacks in a kthread instead of softirq. We observed\nhigh rate of context switch which is caused by this. Out test system has\n64 CPUs and HZ is 1000, so we saw more than 64k context switch per second\nwhich is caused by RCU\u0027s per-CPU kthread.  A trace showed that most of\nthe time the RCU per-CPU kthread doesn\u0027t actually handle any callbacks,\nbut instead just does a very small amount of work handling grace periods.\nThis means that RCU\u0027s per-CPU kthreads are making the scheduler do quite\na bit of work in order to allow a very small amount of RCU-related\nprocessing to be done.\n\nAlex Shi\u0027s analysis determined that this slowdown is due to lock\ncontention within the scheduler.  Unfortunately, as Peter Zijlstra points\nout, the scheduler\u0027s real-time semantics require global action, which\nmeans that this contention is inherent in real-time scheduling.  (Yes,\nperhaps someone will come up with a workaround -- otherwise, -rt is not\ngoing to do well on large SMP systems -- but this patch will work around\nthis issue in the meantime.  And \"the meantime\" might well be forever.)\n\nThis patch therefore re-introduces softirq processing to RCU, but only\nfor core RCU work.  RCU callbacks are still executed in kthread context,\nso that only a small amount of RCU work runs in softirq context in the\ncommon case.  This should minimize ksoftirqd execution, allowing us to\nskip boosting of ksoftirqd for CONFIG_RCU_BOOST\u003dy kernels.\n\nSigned-off-by: Shaohua Li \u003cshaohua.li@intel.com\u003e\nTested-by: \"Alex,Shi\" \u003calex.shi@intel.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "9a432736904d386cda28b987b38ba14dae960ecc",
      "tree": "20294203f9c6132d79737e9ab54c746546afe7d4",
      "parents": [
        "59c5f46fbe01a00eedf54a23789634438bb80603"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 30 20:38:55 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Jun 14 15:25:15 2011 -0700"
      },
      "message": "rcu: Simplify curing of load woes\n\nMake the functions creating the kthreads wake them up.  Leverage the\nfact that the per-node and boost kthreads can run anywhere, thus\ndispensing with the need to wake them up once the incoming CPU has\ngone fully online.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nTested-by: Daniel J Blueman \u003cdaniel.blueman@gmail.com\u003e\n"
    },
    {
      "commit": "d72bce0e67e8afc6eb959f656013cbb577426f1e",
      "tree": "9c93d4df9aa895d6f2f555e0cf50e7ae5ebaded4",
      "parents": [
        "55922c9d1b84b89cb946c777fddccb3247e7df2c"
      ],
      "author": {
        "name": "Peter Zijlstra",
        "email": "peterz@infradead.org",
        "time": "Mon May 30 13:34:51 2011 +0200"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue May 31 10:01:48 2011 +0200"
      },
      "message": "rcu: Cure load woes\n\nCommit cc3ce5176d83 (rcu: Start RCU kthreads in TASK_INTERRUPTIBLE\nstate) fudges a sleeping task\u0027 state, resulting in the scheduler seeing\na TASK_UNINTERRUPTIBLE task going to sleep, but a TASK_INTERRUPTIBLE\ntask waking up. The result is unbalanced load calculation.\n\nThe problem that patch tried to address is that the RCU threads could\nstay in UNINTERRUPTIBLE state for quite a while and triggering the hung\ntask detector due to on-demand wake-ups.\n\nCure the problem differently by always giving the tasks at least one\nwake-up once the CPU is fully up and running, this will kick them out of\nthe initial UNINTERRUPTIBLE state and into the regular INTERRUPTIBLE\nwait state.\n\n[ The alternative would be teaching kthread_create() to start threads as\n  INTERRUPTIBLE but that needs a tad more thought. ]\n\nReported-by: Damien Wyart \u003cdamien.wyart@free.fr\u003e\nSigned-off-by: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nAcked-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nLink: http://lkml.kernel.org/r/1306755291.1200.2872.camel@twins\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "cc3ce5176d83cd8ae1134f86e208ea758d6cb78e",
      "tree": "a28ada4c1e5fd8c3e8210ca1a1df950af8a704ff",
      "parents": [
        "08bca60a6912ad225254250c0a9c3a05b4152cfa"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed May 25 13:42:06 2011 -0700"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat May 28 17:41:56 2011 +0200"
      },
      "message": "rcu: Start RCU kthreads in TASK_INTERRUPTIBLE state\n\nUpon creation, kthreads are in TASK_UNINTERRUPTIBLE state, which can\nresult in softlockup warnings.  Because some of RCU\u0027s kthreads can\nlegitimately be idle indefinitely, start them in TASK_INTERRUPTIBLE\nstate in order to avoid those warnings.\n\nSuggested-by: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nTested-by: Yinghai Lu \u003cyinghai@kernel.org\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "08bca60a6912ad225254250c0a9c3a05b4152cfa",
      "tree": "760b20e6eaaa02412fcecb6bc5c3598b6bc0fdce",
      "parents": [
        "8826f3b0397562eee6f8785d548be9dfdb169100"
      ],
      "author": {
        "name": "Peter Zijlstra",
        "email": "a.p.zijlstra@chello.nl",
        "time": "Fri May 20 16:06:29 2011 -0700"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat May 28 17:41:52 2011 +0200"
      },
      "message": "rcu: Remove waitqueue usage for cpu, node, and boost kthreads\n\nIt is not necessary to use waitqueues for the RCU kthreads because\nwe always know exactly which thread is to be awakened.  In addition,\nwake_up() only issues an actual wakeup when there is a thread waiting on\nthe queue, which was why there was an extra explicit wake_up_process()\nto get the RCU kthreads started.\n\nEliminating the waitqueues (and wake_up()) in favor of wake_up_process()\neliminates the need for the initial wake_up_process() and also shrinks\nthe data structure size a bit.  The wakeup logic is placed in a new\nrcu_wait() macro.\n\nSigned-off-by: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "8826f3b0397562eee6f8785d548be9dfdb169100",
      "tree": "3b911e0ffe56b1792126f3f36f1fa4de39fd5979",
      "parents": [
        "55c2945aa9d4d907ec5ca4f6a4e30ae908d8d30d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed May 11 05:41:41 2011 -0700"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat May 28 17:41:49 2011 +0200"
      },
      "message": "rcu: Avoid acquiring rcu_node locks in timer functions\n\nThis commit switches manipulations of the rcu_node -\u003ewakemask field\nto atomic operations, which allows rcu_cpu_kthread_timer() to avoid\nacquiring the rcu_node lock.  This should avoid the following lockdep\nsplat reported by Valdis Kletnieks:\n\n[   12.872150] usb 1-4: new high speed USB device number 3 using ehci_hcd\n[   12.986667] usb 1-4: New USB device found, idVendor\u003d413c, idProduct\u003d2513\n[   12.986679] usb 1-4: New USB device strings: Mfr\u003d0, Product\u003d0, SerialNumber\u003d0\n[   12.987691] hub 1-4:1.0: USB hub found\n[   12.987877] hub 1-4:1.0: 3 ports detected\n[   12.996372] input: PS/2 Generic Mouse as /devices/platform/i8042/serio1/input/input10\n[   13.071471] udevadm used greatest stack depth: 3984 bytes left\n[   13.172129]\n[   13.172130] \u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\n[   13.172425] [ INFO: possible circular locking dependency detected ]\n[   13.172650] 2.6.39-rc6-mmotm0506 #1\n[   13.172773] -------------------------------------------------------\n[   13.172997] blkid/267 is trying to acquire lock:\n[   13.173009]  (\u0026p-\u003epi_lock){-.-.-.}, at: [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[   13.173009]\n[   13.173009] but task is already holding lock:\n[   13.173009]  (rcu_node_level_0){..-...}, at: [\u003cffffffff810901cc\u003e] rcu_cpu_kthread_timer+0x27/0x58\n[   13.173009]\n[   13.173009] which lock already depends on the new lock.\n[   13.173009]\n[   13.173009]\n[   13.173009] the existing dependency chain (in reverse order) is:\n[   13.173009]\n[   13.173009] -\u003e #2 (rcu_node_level_0){..-...}:\n[   13.173009]        [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[   13.173009]        [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[   13.173009]        [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[   13.173009]        [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[   13.173009]        [\u003cffffffff815697f1\u003e] _raw_spin_lock+0x36/0x45\n[   13.173009]        [\u003cffffffff81090794\u003e] rcu_read_unlock_special+0x8c/0x1d5\n[   13.173009]        [\u003cffffffff8109092c\u003e] __rcu_read_unlock+0x4f/0xd7\n[   13.173009]        [\u003cffffffff81027bd3\u003e] rcu_read_unlock+0x21/0x23\n[   13.173009]        [\u003cffffffff8102cc34\u003e] cpuacct_charge+0x6c/0x75\n[   13.173009]        [\u003cffffffff81030cc6\u003e] update_curr+0x101/0x12e\n[   13.173009]        [\u003cffffffff810311d0\u003e] check_preempt_wakeup+0xf7/0x23b\n[   13.173009]        [\u003cffffffff8102acb3\u003e] check_preempt_curr+0x2b/0x68\n[   13.173009]        [\u003cffffffff81031d40\u003e] ttwu_do_wakeup+0x76/0x128\n[   13.173009]        [\u003cffffffff81031e49\u003e] ttwu_do_activate.constprop.63+0x57/0x5c\n[   13.173009]        [\u003cffffffff81031e96\u003e] scheduler_ipi+0x48/0x5d\n[   13.173009]        [\u003cffffffff810177d5\u003e] smp_reschedule_interrupt+0x16/0x18\n[   13.173009]        [\u003cffffffff815710f3\u003e] reschedule_interrupt+0x13/0x20\n[   13.173009]        [\u003cffffffff810b66d1\u003e] rcu_read_unlock+0x21/0x23\n[   13.173009]        [\u003cffffffff810b739c\u003e] find_get_page+0xa9/0xb9\n[   13.173009]        [\u003cffffffff810b8b48\u003e] filemap_fault+0x6a/0x34d\n[   13.173009]        [\u003cffffffff810d1a25\u003e] __do_fault+0x54/0x3e6\n[   13.173009]        [\u003cffffffff810d447a\u003e] handle_pte_fault+0x12c/0x1ed\n[   13.173009]        [\u003cffffffff810d48f7\u003e] handle_mm_fault+0x1cd/0x1e0\n[   13.173009]        [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[   13.173009]        [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[   13.173009]\n[   13.173009] -\u003e #1 (\u0026rq-\u003elock){-.-.-.}:\n[   13.173009]        [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[   13.173009]        [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[   13.173009]        [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[   13.173009]        [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[   13.173009]        [\u003cffffffff815697f1\u003e] _raw_spin_lock+0x36/0x45\n[   13.173009]        [\u003cffffffff81027e19\u003e] __task_rq_lock+0x8b/0xd3\n[   13.173009]        [\u003cffffffff81032f7f\u003e] wake_up_new_task+0x41/0x108\n[   13.173009]        [\u003cffffffff810376c3\u003e] do_fork+0x265/0x33f\n[   13.173009]        [\u003cffffffff81007d02\u003e] kernel_thread+0x6b/0x6d\n[   13.173009]        [\u003cffffffff8153a9dd\u003e] rest_init+0x21/0xd2\n[   13.173009]        [\u003cffffffff81b1db4f\u003e] start_kernel+0x3bb/0x3c6\n[   13.173009]        [\u003cffffffff81b1d29f\u003e] x86_64_start_reservations+0xaf/0xb3\n[   13.173009]        [\u003cffffffff81b1d393\u003e] x86_64_start_kernel+0xf0/0xf7\n[   13.173009]\n[   13.173009] -\u003e #0 (\u0026p-\u003epi_lock){-.-.-.}:\n[   13.173009]        [\u003cffffffff81067788\u003e] check_prev_add+0x68/0x20e\n[   13.173009]        [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[   13.173009]        [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[   13.173009]        [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[   13.173009]        [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[   13.173009]        [\u003cffffffff815698ea\u003e] _raw_spin_lock_irqsave+0x44/0x57\n[   13.173009]        [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[   13.173009]        [\u003cffffffff81032f3c\u003e] wake_up_process+0x10/0x12\n[   13.173009]        [\u003cffffffff810901e9\u003e] rcu_cpu_kthread_timer+0x44/0x58\n[   13.173009]        [\u003cffffffff81045286\u003e] call_timer_fn+0xac/0x1e9\n[   13.173009]        [\u003cffffffff8104556d\u003e] run_timer_softirq+0x1aa/0x1f2\n[   13.173009]        [\u003cffffffff8103e487\u003e] __do_softirq+0x109/0x26a\n[   13.173009]        [\u003cffffffff8157144c\u003e] call_softirq+0x1c/0x30\n[   13.173009]        [\u003cffffffff81003207\u003e] do_softirq+0x44/0xf1\n[   13.173009]        [\u003cffffffff8103e8b9\u003e] irq_exit+0x58/0xc8\n[   13.173009]        [\u003cffffffff81017f5a\u003e] smp_apic_timer_interrupt+0x79/0x87\n[   13.173009]        [\u003cffffffff81570fd3\u003e] apic_timer_interrupt+0x13/0x20\n[   13.173009]        [\u003cffffffff810bd51a\u003e] get_page_from_freelist+0x2aa/0x310\n[   13.173009]        [\u003cffffffff810bdf03\u003e] __alloc_pages_nodemask+0x178/0x243\n[   13.173009]        [\u003cffffffff8101fe2f\u003e] pte_alloc_one+0x1e/0x3a\n[   13.173009]        [\u003cffffffff810d27fe\u003e] __pte_alloc+0x22/0x14b\n[   13.173009]        [\u003cffffffff810d48a8\u003e] handle_mm_fault+0x17e/0x1e0\n[   13.173009]        [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[   13.173009]        [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[   13.173009]\n[   13.173009] other info that might help us debug this:\n[   13.173009]\n[   13.173009] Chain exists of:\n[   13.173009]   \u0026p-\u003epi_lock --\u003e \u0026rq-\u003elock --\u003e rcu_node_level_0\n[   13.173009]\n[   13.173009]  Possible unsafe locking scenario:\n[   13.173009]\n[   13.173009]        CPU0                    CPU1\n[   13.173009]        ----                    ----\n[   13.173009]   lock(rcu_node_level_0);\n[   13.173009]                                lock(\u0026rq-\u003elock);\n[   13.173009]                                lock(rcu_node_level_0);\n[   13.173009]   lock(\u0026p-\u003epi_lock);\n[   13.173009]\n[   13.173009]  *** DEADLOCK ***\n[   13.173009]\n[   13.173009] 3 locks held by blkid/267:\n[   13.173009]  #0:  (\u0026mm-\u003emmap_sem){++++++}, at: [\u003cffffffff8156cdb4\u003e] do_page_fault+0x1f3/0x5de\n[   13.173009]  #1:  (\u0026yield_timer){+.-...}, at: [\u003cffffffff810451da\u003e] call_timer_fn+0x0/0x1e9\n[   13.173009]  #2:  (rcu_node_level_0){..-...}, at: [\u003cffffffff810901cc\u003e] rcu_cpu_kthread_timer+0x27/0x58\n[   13.173009]\n[   13.173009] stack backtrace:\n[   13.173009] Pid: 267, comm: blkid Not tainted 2.6.39-rc6-mmotm0506 #1\n[   13.173009] Call Trace:\n[   13.173009]  \u003cIRQ\u003e  [\u003cffffffff8154a529\u003e] print_circular_bug+0xc8/0xd9\n[   13.173009]  [\u003cffffffff81067788\u003e] check_prev_add+0x68/0x20e\n[   13.173009]  [\u003cffffffff8100c861\u003e] ? save_stack_trace+0x28/0x46\n[   13.173009]  [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[   13.173009]  [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[   13.173009]  [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[   13.173009]  [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[   13.173009]  [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[   13.173009]  [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[   13.173009]  [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[   13.173009]  [\u003cffffffff815698ea\u003e] _raw_spin_lock_irqsave+0x44/0x57\n[   13.173009]  [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[   13.173009]  [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[   13.173009]  [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[   13.173009]  [\u003cffffffff81032f3c\u003e] wake_up_process+0x10/0x12\n[   13.173009]  [\u003cffffffff810901e9\u003e] rcu_cpu_kthread_timer+0x44/0x58\n[   13.173009]  [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[   13.173009]  [\u003cffffffff81045286\u003e] call_timer_fn+0xac/0x1e9\n[   13.173009]  [\u003cffffffff810451da\u003e] ? del_timer+0x75/0x75\n[   13.173009]  [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[   13.173009]  [\u003cffffffff8104556d\u003e] run_timer_softirq+0x1aa/0x1f2\n[   13.173009]  [\u003cffffffff8103e487\u003e] __do_softirq+0x109/0x26a\n[   13.173009]  [\u003cffffffff8106365f\u003e] ? tick_dev_program_event+0x37/0xf6\n[   13.173009]  [\u003cffffffff810a0e4a\u003e] ? time_hardirqs_off+0x1b/0x2f\n[   13.173009]  [\u003cffffffff8157144c\u003e] call_softirq+0x1c/0x30\n[   13.173009]  [\u003cffffffff81003207\u003e] do_softirq+0x44/0xf1\n[   13.173009]  [\u003cffffffff8103e8b9\u003e] irq_exit+0x58/0xc8\n[   13.173009]  [\u003cffffffff81017f5a\u003e] smp_apic_timer_interrupt+0x79/0x87\n[   13.173009]  [\u003cffffffff81570fd3\u003e] apic_timer_interrupt+0x13/0x20\n[   13.173009]  \u003cEOI\u003e  [\u003cffffffff810bd384\u003e] ? get_page_from_freelist+0x114/0x310\n[   13.173009]  [\u003cffffffff810bd51a\u003e] ? get_page_from_freelist+0x2aa/0x310\n[   13.173009]  [\u003cffffffff812220e7\u003e] ? clear_page_c+0x7/0x10\n[   13.173009]  [\u003cffffffff810bd1ef\u003e] ? prep_new_page+0x14c/0x1cd\n[   13.173009]  [\u003cffffffff810bd51a\u003e] get_page_from_freelist+0x2aa/0x310\n[   13.173009]  [\u003cffffffff810bdf03\u003e] __alloc_pages_nodemask+0x178/0x243\n[   13.173009]  [\u003cffffffff810d46b9\u003e] ? __pmd_alloc+0x87/0x99\n[   13.173009]  [\u003cffffffff8101fe2f\u003e] pte_alloc_one+0x1e/0x3a\n[   13.173009]  [\u003cffffffff810d46b9\u003e] ? __pmd_alloc+0x87/0x99\n[   13.173009]  [\u003cffffffff810d27fe\u003e] __pte_alloc+0x22/0x14b\n[   13.173009]  [\u003cffffffff810d48a8\u003e] handle_mm_fault+0x17e/0x1e0\n[   13.173009]  [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[   13.173009]  [\u003cffffffff810d915f\u003e] ? sys_brk+0x32/0x10c\n[   13.173009]  [\u003cffffffff810a0e4a\u003e] ? time_hardirqs_off+0x1b/0x2f\n[   13.173009]  [\u003cffffffff81065c4f\u003e] ? trace_hardirqs_off_caller+0x3f/0x9c\n[   13.173009]  [\u003cffffffff812235dd\u003e] ? trace_hardirqs_off_thunk+0x3a/0x3c\n[   13.173009]  [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[   14.010075] usb 5-1: new full speed USB device number 2 using uhci_hcd\n\nReported-by: Valdis Kletnieks \u003cValdis.Kletnieks@vt.edu\u003e\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "29f742f88a32c9ab8cf6d9ba69e1ea918be5aa58",
      "tree": "a38aa38c8025e050ec82a7e64d02dca07f90ffc7",
      "parents": [
        "f62508f68d04adefc4cf9b0177ba02c8818b3eec",
        "23b5c8fa01b723c70a20d6e4ef4ff54c7656d6e1"
      ],
      "author": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Fri May 27 12:38:52 2011 +0200"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat May 28 17:41:05 2011 +0200"
      },
      "message": "Merge branch \u0027rcu/urgent\u0027 of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent\n"
    },
    {
      "commit": "23b5c8fa01b723c70a20d6e4ef4ff54c7656d6e1",
      "tree": "d03faad5e19848b35a019793b9a1cbc0bb68a708",
      "parents": [
        "4305ce7894dd38b0633bfc8978437320119223bd"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Sep 07 10:38:22 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 26 09:42:23 2011 -0700"
      },
      "message": "rcu: Decrease memory-barrier usage based on semi-formal proof\n\n(Note: this was reverted, and is now being re-applied in pieces, with\nthis being the fifth and final piece.  See below for the reason that\nit is now felt to be safe to re-apply this.)\n\nCommit d09b62d fixed grace-period synchronization, but left some smp_mb()\ninvocations in rcu_process_callbacks() that are no longer needed, but\nsheer paranoia prevented them from being removed.  This commit removes\nthem and provides a proof of correctness in their absence.  It also adds\na memory barrier to rcu_report_qs_rsp() immediately before the update to\nrsp-\u003ecompleted in order to handle the theoretical possibility that the\ncompiler or CPU might move massive quantities of code into a lock-based\ncritical section.  This also proves that the sheer paranoia was not\nentirely unjustified, at least from a theoretical point of view.\n\nIn addition, the old dyntick-idle synchronization depended on the fact\nthat grace periods were many milliseconds in duration, so that it could\nbe assumed that no dyntick-idle CPU could reorder a memory reference\nacross an entire grace period.  Unfortunately for this design, the\naddition of expedited grace periods breaks this assumption, which has\nthe unfortunate side-effect of requiring atomic operations in the\nfunctions that track dyntick-idle state for RCU.  (There is some hope\nthat the algorithms used in user-level RCU might be applied here, but\nsome work is required to handle the NMIs that user-space applications\ncan happily ignore.  For the short term, better safe than sorry.)\n\nThis proof assumes that neither compiler nor CPU will allow a lock\nacquisition and release to be reordered, as doing so can result in\ndeadlock.  The proof is as follows:\n\n1.\tA given CPU declares a quiescent state under the protection of\n\tits leaf rcu_node\u0027s lock.\n\n2.\tIf there is more than one level of rcu_node hierarchy, the\n\tlast CPU to declare a quiescent state will also acquire the\n\t-\u003elock of the next rcu_node up in the hierarchy,  but only\n\tafter releasing the lower level\u0027s lock.  The acquisition of this\n\tlock clearly cannot occur prior to the acquisition of the leaf\n\tnode\u0027s lock.\n\n3.\tStep 2 repeats until we reach the root rcu_node structure.\n\tPlease note again that only one lock is held at a time through\n\tthis process.  The acquisition of the root rcu_node\u0027s -\u003elock\n\tmust occur after the release of that of the leaf rcu_node.\n\n4.\tAt this point, we set the -\u003ecompleted field in the rcu_state\n\tstructure in rcu_report_qs_rsp().  However, if the rcu_node\n\thierarchy contains only one rcu_node, then in theory the code\n\tpreceding the quiescent state could leak into the critical\n\tsection.  We therefore precede the update of -\u003ecompleted with a\n\tmemory barrier.  All CPUs will therefore agree that any updates\n\tpreceding any report of a quiescent state will have happened\n\tbefore the update of -\u003ecompleted.\n\n5.\tRegardless of whether a new grace period is needed, rcu_start_gp()\n\twill propagate the new value of -\u003ecompleted to all of the leaf\n\trcu_node structures, under the protection of each rcu_node\u0027s -\u003elock.\n\tIf a new grace period is needed immediately, this propagation\n\twill occur in the same critical section that -\u003ecompleted was\n\tset in, but courtesy of the memory barrier in #4 above, is still\n\tseen to follow any pre-quiescent-state activity.\n\n6.\tWhen a given CPU invokes __rcu_process_gp_end(), it becomes\n\taware of the end of the old grace period and therefore makes\n\tany RCU callbacks that were waiting on that grace period eligible\n\tfor invocation.\n\n\tIf this CPU is the same one that detected the end of the grace\n\tperiod, and if there is but a single rcu_node in the hierarchy,\n\twe will still be in the single critical section.  In this case,\n\tthe memory barrier in step #4 guarantees that all callbacks will\n\tbe seen to execute after each CPU\u0027s quiescent state.\n\n\tOn the other hand, if this is a different CPU, it will acquire\n\tthe leaf rcu_node\u0027s -\u003elock, and will again be serialized after\n\teach CPU\u0027s quiescent state for the old grace period.\n\nOn the strength of this proof, this commit therefore removes the memory\nbarriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp().\nThe effect is to reduce the number of memory barriers by one and to\nreduce the frequency of execution from about once per scheduling tick\nper CPU to once per grace period.\n\nThis was reverted do to hangs found during testing by Yinghai Lu and\nIngo Molnar.  Frederic Weisbecker supplied Yinghai with tracing that\nlocated the underlying problem, and Frederic also provided the fix.\n\nThe underlying problem was that the HARDIRQ_ENTER() macro from\nlib/locking-selftest.c invoked irq_enter(), which in turn invokes\nrcu_irq_enter(), but HARDIRQ_EXIT() invoked __irq_exit(), which\ndoes not invoke rcu_irq_exit().  This situation resulted in calls\nto rcu_irq_enter() that were not balanced by the required calls to\nrcu_irq_exit().  Therefore, after these locking selftests completed,\nRCU\u0027s dyntick-idle nesting count was a large number (for example,\n72), which caused RCU to to conclude that the affected CPU was not in\ndyntick-idle mode when in fact it was.\n\nRCU would therefore incorrectly wait for this dyntick-idle CPU, resulting\nin hangs.\n\nIn contrast, with Frederic\u0027s patch, which replaces the irq_enter()\nin HARDIRQ_ENTER() with an __irq_enter(), these tests don\u0027t ever call\neither rcu_irq_enter() or rcu_irq_exit(), which works because the CPU\nrunning the test is already marked as not being in dyntick-idle mode.\nThis means that the rcu_irq_enter() and rcu_irq_exit() calls and RCU\nthen has no problem working out which CPUs are in dyntick-idle mode and\nwhich are not.\n\nThe reason that the imbalance was not noticed before the barrier patch\nwas applied is that the old implementation of rcu_enter_nohz() ignored\nthe nesting depth.  This could still result in delays, but much shorter\nones.  Whenever there was a delay, RCU would IPI the CPU with the\nunbalanced nesting level, which would eventually result in rcu_enter_nohz()\nbeing called, which in turn would force RCU to see that the CPU was in\ndyntick-idle mode.\n\nThe reason that very few people noticed the problem is that the mismatched\nirq_enter() vs. __irq_exit() occured only when the kernel was built with\nCONFIG_DEBUG_LOCKING_API_SELFTESTS.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "4305ce7894dd38b0633bfc8978437320119223bd",
      "tree": "eafe4497236f8dd4ddfdf90fe06a5377912a9c35",
      "parents": [
        "b5904090c754327ed6c2ecaefed4f7d473df393f"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 16 14:27:31 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 26 09:42:22 2011 -0700"
      },
      "message": "rcu: Make rcu_enter_nohz() pay attention to nesting\n\nThe old version of rcu_enter_nohz() forced RCU into nohz mode even if\nthe nesting count was non-zero.  This change causes rcu_enter_nohz()\nto hold off for non-zero nesting counts.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "b5904090c754327ed6c2ecaefed4f7d473df393f",
      "tree": "46cf53f98413171d92de3b5e11c9327309f240b7",
      "parents": [
        "1135633bddcf7a819a1490c18d04965c490bcc1e"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 16 02:52:04 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 26 09:42:21 2011 -0700"
      },
      "message": "rcu: Don\u0027t do reschedule unless in irq\n\nCondition the set_need_resched() in rcu_irq_exit() on in_irq().  This\nshould be a no-op, because rcu_irq_exit() should only be called from irq.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "1135633bddcf7a819a1490c18d04965c490bcc1e",
      "tree": "99facc2b3416a7c00cf042d2f782a87859e30d26",
      "parents": [
        "0bbcc529fcea9c7de5e2e7243f9913b8f7302a8c"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 16 02:44:06 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 26 09:42:21 2011 -0700"
      },
      "message": "rcu: Remove old memory barriers from rcu_process_callbacks()\n\nSecond step of partitioning of commit e59fb3120b.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "0bbcc529fcea9c7de5e2e7243f9913b8f7302a8c",
      "tree": "22403b7c9bf3b87818c3a8a606a1bc33dd12bd1a",
      "parents": [
        "ba9f207c9f82115aba4ce04b22e0081af0ae300f"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 16 02:24:04 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 26 09:42:20 2011 -0700"
      },
      "message": "rcu: Add memory barriers\n\nAdd the memory barriers added by e59fb3120b.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "268bb0ce3e87872cb9290c322b0d35bce230d88f",
      "tree": "c8331ade4a3e24fc589c4eb62731bc2312d35333",
      "parents": [
        "257313b2a87795e07a0bdf58d0fffbdba8b31051"
      ],
      "author": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Fri May 20 12:50:29 2011 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Fri May 20 12:50:29 2011 -0700"
      },
      "message": "sanitize \u003clinux/prefetch.h\u003e usage\n\nCommit e66eed651fd1 (\"list: remove prefetching from regular list\niterators\") removed the include of prefetch.h from list.h, which\nuncovered several cases that had apparently relied on that rather\nobscure header file dependency.\n\nSo this fixes things up a bit, using\n\n   grep -L linux/prefetch.h $(git grep -l \u0027[^a-z_]prefetchw*(\u0027 -- \u0027*.[ch]\u0027)\n   grep -L \u0027prefetchw*(\u0027 $(git grep -l \u0027linux/prefetch.h\u0027 -- \u0027*.[ch]\u0027)\n\nto guide us in finding files that either need \u003clinux/prefetch.h\u003e\ninclusion, or have it despite not needing it.\n\nThere are more of them around (mostly network drivers), but this gets\nmany core ones.\n\nReported-by: Stephen Rothwell \u003csfr@canb.auug.org.au\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "80d02085d99039b3b7f3a73c8896226b0cb1ba07",
      "tree": "c310902423ecb00effadcb59c60cbf118d4037cb",
      "parents": [
        "11c476f31a0fabc6e604da5b09a6590b57c3fb20"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 12 01:08:07 2011 -0700"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu May 19 23:25:29 2011 +0200"
      },
      "message": "Revert \"rcu: Decrease memory-barrier usage based on semi-formal proof\"\n\nThis reverts commit e59fb3120becfb36b22ddb8bd27d065d3cdca499.\n\nThis reversion was due to (extreme) boot-time slowdowns on SPARC seen by\nYinghai Lu and on x86 by Ingo\n.\nThis is a non-trivial reversion due to intervening commits.\n\nConflicts:\n\n\tDocumentation/RCU/trace.txt\n\tkernel/rcutree.c\n\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "1217ed1ba5c67393293dfb0f03c353b118dadeb4",
      "tree": "a765356c8418e134de85fd05d9fe6eda41de859c",
      "parents": [
        "29ce831000081dd757d3116bf774aafffc4b6b20"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed May 04 21:43:49 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Sat May 07 22:50:45 2011 -0700"
      },
      "message": "rcu: permit rcu_read_unlock() to be called while holding runqueue locks\n\nAvoid calling into the scheduler while holding core RCU locks.  This\nallows rcu_read_unlock() to be called while holding the runqueue locks,\nbut only as long as there was no chance of the RCU read-side critical\nsection having been preempted.  (Otherwise, if RCU priority boosting\nis enabled, rcu_read_unlock() might call into the scheduler in order to\nunboost itself, which might allows self-deadlock on the runqueue locks\nwithin the scheduler.)\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "29ce831000081dd757d3116bf774aafffc4b6b20",
      "tree": "0b992d993b02d3479a150e9fc508d110dc45631d",
      "parents": [
        "bad6e1393cb505fe17747344a23666464daa3fa7"
      ],
      "author": {
        "name": "Gleb Natapov",
        "email": "gleb@redhat.com",
        "time": "Wed May 04 16:31:03 2011 +0300"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: provide rcu_virt_note_context_switch() function.\n\nProvide rcu_virt_note_context_switch() for vitalization use to note\nquiescent state during guest entry.\n\nSigned-off-by: Gleb Natapov \u003cgleb@redhat.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "bad6e1393cb505fe17747344a23666464daa3fa7",
      "tree": "521dcada78d0f19400d14547381f0f3b2e38fea2",
      "parents": [
        "b554d7de8d112fca4188da3bf0d7f8b56f42fb95"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 02 23:40:04 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: get rid of signed overflow in check_cpu_stall()\n\nSigned integer overflow is undefined by the C standard, so move\ncalculations to unsigned.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "2655d57ef35aa327a2e58a1c5dc7b65c65003f4e",
      "tree": "4a71e82b23ee84705cad15cd16490f8c5aace74f",
      "parents": [
        "baa1ae0c9f1c618bc60706efa75fef3508bcee58"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Apr 07 22:47:23 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: prevent call_rcu() from diving into rcu core if irqs disabled\n\nThis commit marks a first step towards making call_rcu() have\nreal-time behavior.  If irqs are disabled, don\u0027t dive into the\nRCU core.  Later on, this new early exit will wake up the\nper-CPU kthread, which first must be modified to handle the\ncases involving callback storms.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "baa1ae0c9f1c618bc60706efa75fef3508bcee58",
      "tree": "e9a4558a3fcef41e42477d6461ccf655d01d5432",
      "parents": [
        "9ab1544eb4196ca8d05c433b2eb56f74496b1ee3"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Sat Mar 26 22:01:35 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: further lower priority in rcu_yield()\n\nAlthough rcu_yield() dropped from real-time to normal priority, there\nis always the possibility that the competing tasks have been niced.\nSo nice to 19 in rcu_yield() to help ensure that other tasks have a\nbetter chance of running.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "9ab1544eb4196ca8d05c433b2eb56f74496b1ee3",
      "tree": "be3a7897cf52920df4da41ded060e23150bdb849",
      "parents": [
        "6cc68793e380bb51f447d8d02af873b7bc01f222"
      ],
      "author": {
        "name": "Lai Jiangshan",
        "email": "laijs@cn.fujitsu.com",
        "time": "Fri Mar 18 11:15:47 2011 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: introduce kfree_rcu()\n\nMany rcu callbacks functions just call kfree() on the base structure.\nThese functions are trivial, but their size adds up, and furthermore\nwhen they are used in a kernel module, that module must invoke the\nhigh-latency rcu_barrier() function at module-unload time.\n\nThe kfree_rcu() function introduced by this commit addresses this issue.\nRather than encoding a function address in the embedded rcu_head\nstructure, kfree_rcu() instead encodes the offset of the rcu_head\nstructure within the base structure.  Because the functions are not\nallowed in the low-order 4096 bytes of kernel virtual memory, offsets\nup to 4095 bytes can be accommodated.  If the offset is larger than\n4095 bytes, a compile-time error will be generated in __kfree_rcu().\nIf this error is triggered, you can either fall back to use of call_rcu()\nor rearrange the structure to position the rcu_head structure into the\nfirst 4096 bytes.\n\nNote that the allowable offset might decrease in the future, for example,\nto allow something like kmem_cache_free_rcu().\n\nThe new kfree_rcu() function can replace code as follows:\n\n\tcall_rcu(\u0026p-\u003ercu, simple_kfree_callback);\n\nwhere \"simple_kfree_callback()\" might be defined as follows:\n\n\tvoid simple_kfree_callback(struct rcu_head *p)\n\t{\n\t\tstruct foo *q \u003d container_of(p, struct foo, rcu);\n\n\t\tkfree(q);\n\t}\n\nwith the following:\n\n\tkfree_rcu(\u0026p-\u003ercu, rcu);\n\nNote that the \"rcu\" is the name of a field in the structure being\nfreed.  The reason for using this rather than passing in a pointer\nto the base structure is that the above approach allows better type\nchecking.\n\nThis commit is based on earlier work by Lai Jiangshan and Manfred Spraul:\n\nLai\u0027s V1 patch: http://lkml.org/lkml/2008/9/18/1\nManfred\u0027s patch: http://lkml.org/lkml/2009/1/2/115\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Manfred Spraul \u003cmanfred@colorfullife.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: David Howells \u003cdhowells@redhat.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "6cc68793e380bb51f447d8d02af873b7bc01f222",
      "tree": "f2b66ace23acc0a31a08f136ad25659d6b51c4b1",
      "parents": [
        "13491a0ee1ef862b6c842132b6eb9c5e721af5ad"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Mar 02 13:15:15 2011 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:59 2011 -0700"
      },
      "message": "rcu: fix spelling\n\nThe \"preemptible\" spelling is preferable.  May as well fix it.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "f0a07aeaf8935b7e9ef8032ce6546169f143951c",
      "tree": "31c6ee98ebb7e3040ad036415702eb23ff929e01",
      "parents": [
        "108aae22339f445c134aeb48eca25df1014ab08d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed Feb 23 11:10:52 2011 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:57 2011 -0700"
      },
      "message": "rcu: Switch to this_cpu() primitives\n\nThis removes a couple of lines from invoke_rcu_cpu_kthread(), improving\nreadability.\n\nReported-by: Christoph Lameter \u003ccl@linux.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "5ece5bab3ed8594ce2c85c6c6e6b82109db36ca7",
      "tree": "c9ef8faa5dbb9e7c82893657e5aa2c1040987f96",
      "parents": [
        "15ba0ba860871cf74b48b1bb47c26c91a66126f3"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Fri Apr 22 18:08:51 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:57 2011 -0700"
      },
      "message": "rcu: Add forward-progress diagnostic for per-CPU kthreads\n\nIncrement a per-CPU counter on each pass through rcu_cpu_kthread()\u0027s\nservice loop, and add it to the rcudata trace output.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "15ba0ba860871cf74b48b1bb47c26c91a66126f3",
      "tree": "2043eeca7d6df62fc0ae918b61abada073f81415",
      "parents": [
        "a9f4793d8900dc5dc09b3951bdcd4731290e06fe"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed Apr 06 16:01:16 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:56 2011 -0700"
      },
      "message": "rcu: add grace-period age and more kthread state to tracing\n\nThis commit adds the age in jiffies of the current grace period along\nwith the duration in jiffies of the longest grace period since boot\nto the rcu/rcugp debugfs file.  It also adds an additional \"O\" state\nto kthread tracing to differentiate between the kthread waiting due to\nhaving nothing to do on the one hand and waiting due to being on the\nwrong CPU on the other hand.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "4a29865689dbb87a02e3b0fff4a4ae5041273173",
      "tree": "72c9f1641a9fb05e3ae4d8cc068f62f9c566bae9",
      "parents": [
        "d71df90eadfc35aa549ff9a850842673febca71f"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Sun Apr 03 21:33:51 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:56 2011 -0700"
      },
      "message": "rcu: make rcutorture version numbers available through debugfs\n\nIt is not possible to accurately correlate rcutorture output with that\nof debugfs.  This patch therefore adds a debugfs file that prints out\nthe rcutorture version number, permitting easy correlation.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "d71df90eadfc35aa549ff9a850842673febca71f",
      "tree": "dd275a3f4848784bc6625574341c11befc1b3823",
      "parents": [
        "0ac3d136b2e3cdf1161178223bc5da14a06241d0"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Tue Mar 29 17:48:28 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:56 2011 -0700"
      },
      "message": "rcu: add tracing for RCU\u0027s kthread run states.\n\nAdd tracing to help debugging situations when RCU\u0027s kthreads are not\nrunning but are supposed to be.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "e3995a25fa361ce987a7d0ade00b17e3151519d7",
      "tree": "ccf8a6ae71bc5cb289080b04f00170a758e33c59",
      "parents": [
        "0f962a5e7277c34987b77dc82fc9aefcedc95e27"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Mon Apr 18 15:31:26 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:55 2011 -0700"
      },
      "message": "rcu: put per-CPU kthread at non-RT priority during CPU hotplug operations\n\nIf you are doing CPU hotplug operations, it is best not to have\nCPU-bound realtime tasks running CPU-bound on the outgoing CPU.\nSo this commit makes per-CPU kthreads run at non-realtime priority\nduring that time.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "0f962a5e7277c34987b77dc82fc9aefcedc95e27",
      "tree": "b265d93dcc8f2669f8fb9b353344b9f6cc354728",
      "parents": [
        "27f4d28057adf98750cf863c40baefb12f5b6d21"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Thu Apr 14 12:13:53 2011 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:55 2011 -0700"
      },
      "message": "rcu: Force per-rcu_node kthreads off of the outgoing CPU\n\nThe scheduler has had some heartburn in the past when too many real-time\nkthreads were affinitied to the outgoing CPU.  So, this commit lightens\nthe load by forcing the per-rcu_node and the boost kthreads off of the\noutgoing CPU.  Note that RCU\u0027s per-CPU kthread remains on the outgoing\nCPU until the bitter end, as it must in order to preserve correctness.\n\nAlso avoid disabling hardirqs across calls to set_cpus_allowed_ptr(),\ngiven that this function can block.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "27f4d28057adf98750cf863c40baefb12f5b6d21",
      "tree": "a66584d2cb68cebda327313f78b8f4eb602ed4ef",
      "parents": [
        "a26ac2455ffcf3be5c6ef92bc6df7182700f2114"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Mon Feb 07 12:47:15 2011 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:55 2011 -0700"
      },
      "message": "rcu: priority boosting for TREE_PREEMPT_RCU\n\nAdd priority boosting for TREE_PREEMPT_RCU, similar to that for\nTINY_PREEMPT_RCU.  This is enabled by the default-off RCU_BOOST\nkernel parameter.  The priority to which to boost preempted\nRCU readers is controlled by the RCU_BOOST_PRIO kernel parameter\n(defaulting to real-time priority 1) and the time to wait before\nboosting the readers who are blocking a given grace period is\ncontrolled by the RCU_BOOST_DELAY kernel parameter (defaulting to\n500 milliseconds).\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "a26ac2455ffcf3be5c6ef92bc6df7182700f2114",
      "tree": "601697c7c3fd152a1b3f29f43d3a028fc8fefd5f",
      "parents": [
        "12f5f524cafef3ab689929b118f2dfb8bf2be321"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Wed Jan 12 14:10:23 2011 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:54 2011 -0700"
      },
      "message": "rcu: move TREE_RCU from softirq to kthread\n\nIf RCU priority boosting is to be meaningful, callback invocation must\nbe boosted in addition to preempted RCU readers.  Otherwise, in presence\nof CPU real-time threads, the grace period ends, but the callbacks don\u0027t\nget invoked.  If the callbacks don\u0027t get invoked, the associated memory\ndoesn\u0027t get freed, so the system is still subject to OOM.\n\nBut it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit\nmoves the callback invocations to a kthread, which can be boosted easily.\n\nAlso add comments and properly synchronized all accesses to\nrcu_cpu_kthread_task, as suggested by Lai Jiangshan.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "12f5f524cafef3ab689929b118f2dfb8bf2be321",
      "tree": "639473556b6edf9b79e0a18d5ba58f80eea76519",
      "parents": [
        "e59fb3120becfb36b22ddb8bd27d065d3cdca499"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paul.mckenney@linaro.org",
        "time": "Mon Nov 29 21:56:39 2010 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:54 2011 -0700"
      },
      "message": "rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists\n\nCombine the current TREE_PREEMPT_RCU -\u003eblocked_tasks[] lists in the\nrcu_node structure into a single -\u003eblkd_tasks list with -\u003egp_tasks\nand -\u003eexp_tasks tail pointers.  This is in preparation for RCU priority\nboosting, which will add a third dimension to the combinatorial explosion\nin the -\u003eblocked_tasks[] case, but simply a third pointer in the new\n-\u003eblkd_tasks case.\n\nAlso update documentation to reflect blocked_tasks[] merge\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "e59fb3120becfb36b22ddb8bd27d065d3cdca499",
      "tree": "37eaadfe112b64caae943fc7469274bc96553d92",
      "parents": [
        "a00e0d714fbded07a7a2254391ce9ed5a5cb9d82"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Sep 07 10:38:22 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:54 2011 -0700"
      },
      "message": "rcu: Decrease memory-barrier usage based on semi-formal proof\n\nCommit d09b62d fixed grace-period synchronization, but left some smp_mb()\ninvocations in rcu_process_callbacks() that are no longer needed, but\nsheer paranoia prevented them from being removed.  This commit removes\nthem and provides a proof of correctness in their absence.  It also adds\na memory barrier to rcu_report_qs_rsp() immediately before the update to\nrsp-\u003ecompleted in order to handle the theoretical possibility that the\ncompiler or CPU might move massive quantities of code into a lock-based\ncritical section.  This also proves that the sheer paranoia was not\nentirely unjustified, at least from a theoretical point of view.\n\nIn addition, the old dyntick-idle synchronization depended on the fact\nthat grace periods were many milliseconds in duration, so that it could\nbe assumed that no dyntick-idle CPU could reorder a memory reference\nacross an entire grace period.  Unfortunately for this design, the\naddition of expedited grace periods breaks this assumption, which has\nthe unfortunate side-effect of requiring atomic operations in the\nfunctions that track dyntick-idle state for RCU.  (There is some hope\nthat the algorithms used in user-level RCU might be applied here, but\nsome work is required to handle the NMIs that user-space applications\ncan happily ignore.  For the short term, better safe than sorry.)\n\nThis proof assumes that neither compiler nor CPU will allow a lock\nacquisition and release to be reordered, as doing so can result in\ndeadlock.  The proof is as follows:\n\n1.\tA given CPU declares a quiescent state under the protection of\n\tits leaf rcu_node\u0027s lock.\n\n2.\tIf there is more than one level of rcu_node hierarchy, the\n\tlast CPU to declare a quiescent state will also acquire the\n\t-\u003elock of the next rcu_node up in the hierarchy,  but only\n\tafter releasing the lower level\u0027s lock.  The acquisition of this\n\tlock clearly cannot occur prior to the acquisition of the leaf\n\tnode\u0027s lock.\n\n3.\tStep 2 repeats until we reach the root rcu_node structure.\n\tPlease note again that only one lock is held at a time through\n\tthis process.  The acquisition of the root rcu_node\u0027s -\u003elock\n\tmust occur after the release of that of the leaf rcu_node.\n\n4.\tAt this point, we set the -\u003ecompleted field in the rcu_state\n\tstructure in rcu_report_qs_rsp().  However, if the rcu_node\n\thierarchy contains only one rcu_node, then in theory the code\n\tpreceding the quiescent state could leak into the critical\n\tsection.  We therefore precede the update of -\u003ecompleted with a\n\tmemory barrier.  All CPUs will therefore agree that any updates\n\tpreceding any report of a quiescent state will have happened\n\tbefore the update of -\u003ecompleted.\n\n5.\tRegardless of whether a new grace period is needed, rcu_start_gp()\n\twill propagate the new value of -\u003ecompleted to all of the leaf\n\trcu_node structures, under the protection of each rcu_node\u0027s -\u003elock.\n\tIf a new grace period is needed immediately, this propagation\n\twill occur in the same critical section that -\u003ecompleted was\n\tset in, but courtesy of the memory barrier in #4 above, is still\n\tseen to follow any pre-quiescent-state activity.\n\n6.\tWhen a given CPU invokes __rcu_process_gp_end(), it becomes\n\taware of the end of the old grace period and therefore makes\n\tany RCU callbacks that were waiting on that grace period eligible\n\tfor invocation.\n\n\tIf this CPU is the same one that detected the end of the grace\n\tperiod, and if there is but a single rcu_node in the hierarchy,\n\twe will still be in the single critical section.  In this case,\n\tthe memory barrier in step #4 guarantees that all callbacks will\n\tbe seen to execute after each CPU\u0027s quiescent state.\n\n\tOn the other hand, if this is a different CPU, it will acquire\n\tthe leaf rcu_node\u0027s -\u003elock, and will again be serialized after\n\teach CPU\u0027s quiescent state for the old grace period.\n\nOn the strength of this proof, this commit therefore removes the memory\nbarriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp().\nThe effect is to reduce the number of memory barriers by one and to\nreduce the frequency of execution from about once per scheduling tick\nper CPU to once per grace period.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "a00e0d714fbded07a7a2254391ce9ed5a5cb9d82",
      "tree": "7c213dbf1e2561655d07749b6d689027460fb8cc",
      "parents": [
        "0ee5623f9a6e52df90a78bd21179f8ab370e102e"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Feb 08 17:14:39 2011 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu May 05 23:16:54 2011 -0700"
      },
      "message": "rcu: Remove conditional compilation for RCU CPU stall warnings\n\nThe RCU CPU stall warnings can now be controlled using the\nrcu_cpu_stall_suppress boot-time parameter or via the same parameter\nfrom sysfs.  There is therefore no longer any reason to have\nkernel config parameters for this feature.  This commit therefore\nremoves the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE\nkernel config parameters.  The RCU_CPU_STALL_TIMEOUT parameter remains\nto allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter\nremains to allow task-stall information to be suppressed if desired.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "72eb6a791459c87a0340318840bb3bd9252b627b",
      "tree": "3bfb8ad99f9c7e511f37f72d57b56a2cea06d753",
      "parents": [
        "23d69b09b78c4876e134f104a3814c30747c53f1",
        "55ee4ef30241a62b700f79517e6d5ef2ddbefa67"
      ],
      "author": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Fri Jan 07 17:02:58 2011 -0800"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Fri Jan 07 17:02:58 2011 -0800"
      },
      "message": "Merge branch \u0027for-2.6.38\u0027 of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu\n\n* \u0027for-2.6.38\u0027 of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)\n  gameport: use this_cpu_read instead of lookup\n  x86: udelay: Use this_cpu_read to avoid address calculation\n  x86: Use this_cpu_inc_return for nmi counter\n  x86: Replace uses of current_cpu_data with this_cpu ops\n  x86: Use this_cpu_ops to optimize code\n  vmstat: User per cpu atomics to avoid interrupt disable / enable\n  irq_work: Use per cpu atomics instead of regular atomics\n  cpuops: Use cmpxchg for xchg to avoid lock semantics\n  x86: this_cpu_cmpxchg and this_cpu_xchg operations\n  percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support\n  percpu,x86: relocate this_cpu_add_return() and friends\n  connector: Use this_cpu operations\n  xen: Use this_cpu_inc_return\n  taskstats: Use this_cpu_ops\n  random: Use this_cpu_inc_return\n  fs: Use this_cpu_inc_return in buffer.c\n  highmem: Use this_cpu_xx_return() operations\n  vmstat: Use this_cpu_inc_return for vm statistics\n  x86: Support for this_cpu_add, sub, dec, inc_return\n  percpu: Generic support for this_cpu_add, sub, dec, inc_return\n  ...\n\nFixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}\nas per Tejun.\n"
    },
    {
      "commit": "b52573d2796274f7f31cfeff7185c320adcd4f12",
      "tree": "61580632fa8fbf80225ba7339274ada0c013a01b",
      "parents": [
        "0209f6490b030f35349a2bb71294f3fd75b0f36d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Dec 14 17:36:02 2010 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 17 12:34:49 2010 -0800"
      },
      "message": "rcu: reduce __call_rcu()-induced contention on rcu_node structures\n\nWhen the current __call_rcu() function was written, the expedited\nAPIs did not exist.  The __call_rcu() implementation therefore went\nto great lengths to detect the end of old grace periods and to start\nnew ones, all in the name of reducing grace-period latency.  Now the\nexpedited APIs do exist, and the usage of __call_rcu() has increased\nconsiderably.  This commit therefore causes __call_rcu() to avoid\nworrying about grace periods unless there are a large number of\nRCU callbacks stacked up on the current CPU.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "0209f6490b030f35349a2bb71294f3fd75b0f36d",
      "tree": "159e233c6fcaf63fbb1a18f5db54af38a8336ee3",
      "parents": [
        "121dfc4b3eba9e2f3c42d35205a3510cc65b9931"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Dec 14 16:07:52 2010 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 17 12:34:20 2010 -0800"
      },
      "message": "rcu: limit rcu_node leaf-level fanout\n\nSome recent benchmarks have indicated possible lock contention on the\nleaf-level rcu_node locks.  This commit therefore limits the number of\nCPUs per leaf-level rcu_node structure to 16, in other words, there\ncan be at most 16 rcu_data structures fanning into a given rcu_node\nstructure.  Prior to this, the limit was 32 on 32-bit systems and 64 on\n64-bit systems.\n\nNote that the fanout of non-leaf rcu_node structures is unchanged.  The\norganization of accesses to the rcu_node tree is such that references\nto non-leaf rcu_node structures are much less frequent than to the\nleaf structures.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "121dfc4b3eba9e2f3c42d35205a3510cc65b9931",
      "tree": "bd132a839cf3618f1d7602efbb1e144a8e04cec4",
      "parents": [
        "5ff8e6f0535fe730e921ca347bc38dcb9e01791a"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 10 15:02:47 2010 -0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 17 12:34:20 2010 -0800"
      },
      "message": "rcu: fine-tune grace-period begin/end checks\n\nUse the CPU\u0027s bit in rnp-\u003eqsmask to determine whether or not the CPU\nshould try to report a quiescent state.  Handle overflow in the check\nfor rdp-\u003egpnum having fallen behind.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "5ff8e6f0535fe730e921ca347bc38dcb9e01791a",
      "tree": "84940db74c49e9312cd6b0295fa03a04603673a3",
      "parents": [
        "20377f32dcb77941d450728da18cce5b1a7faec5"
      ],
      "author": {
        "name": "Frederic Weisbecker",
        "email": "fweisbec@gmail.com",
        "time": "Fri Dec 10 22:11:11 2010 +0100"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 17 12:34:19 2010 -0800"
      },
      "message": "rcu: Keep gpnum and completed fields synchronized\n\nWhen a CPU that was in an extended quiescent state wakes\nup and catches up with grace periods that remote CPUs\ncompleted on its behalf, we update the completed field\nbut not the gpnum that keeps a stale value of a backward\ngrace period ID.\n\nLater, note_new_gpnum() will interpret the shift between\nthe local CPU and the node grace period ID as some new grace\nperiod to handle and will then start to hunt quiescent state.\n\nBut if every grace periods have already been completed, this\ninterpretation becomes broken. And we\u0027ll be stuck in clusters\nof spurious softirqs because rcu_report_qs_rdp() will make\nthis broken state run into infinite loop.\n\nThe solution, as suggested by Lai Jiangshan, is to ensure that\nthe gpnum and completed fields are well synchronized when we catch\nup with completed grace periods on their behalf by other cpus.\nThis way we won\u0027t start noting spurious new grace periods.\n\nSuggested-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Frederic Weisbecker \u003cfweisbec@gmail.com\u003e\nCc: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: Ingo Molnar \u003cmingo@elte.hu\u003e\nCc: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nCc: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nCc: Steven Rostedt \u003crostedt@goodmis.org\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "20377f32dcb77941d450728da18cce5b1a7faec5",
      "tree": "ef92da7c1fabcc68685021655842b3b18a6ee773",
      "parents": [
        "e27fc9641e8ddc8146f8e01f06e5eba2469698de"
      ],
      "author": {
        "name": "Frederic Weisbecker",
        "email": "fweisbec@gmail.com",
        "time": "Fri Dec 10 22:11:10 2010 +0100"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Dec 17 12:34:18 2010 -0800"
      },
      "message": "rcu: Stop chasing QS if another CPU did it for us\n\nWhen a CPU is idle and others CPUs handled its extended\nquiescent state to complete grace periods on its behalf,\nit will catch up with completed grace periods numbers\nwhen it wakes up.\n\nBut at this point there might be no more grace period to\ncomplete, but still the woken CPU always keeps its stale\nqs_pending value and will then continue to chase quiescent\nstates even if its not needed anymore.\n\nThis results in clusters of spurious softirqs until a new\nreal grace period is started. Because if we continue to\nchase quiescent states but we have completed every grace\nperiods, rcu_report_qs_rdp() is puzzled and makes that\nstate run into infinite loops.\n\nAs suggested by Lai Jiangshan, just reset qs_pending if\nsomeone completed every grace periods on our behalf.\n\nSuggested-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Frederic Weisbecker \u003cfweisbec@gmail.com\u003e\nCc: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: Ingo Molnar \u003cmingo@elte.hu\u003e\nCc: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nCc: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nCc: Steven Rostedt \u003crostedt@goodmis.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "909ea96468096b07fbb41aaf69be060d92bd9271",
      "tree": "a7e015edd96b5f674874fe78cdd889769e130a2a",
      "parents": [
        "780f36d8b3fa9572f731d4fb85067b2e45e6f993"
      ],
      "author": {
        "name": "Christoph Lameter",
        "email": "cl@linux.com",
        "time": "Wed Dec 08 16:22:55 2010 +0100"
      },
      "committer": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Fri Dec 17 15:07:19 2010 +0100"
      },
      "message": "core: Replace __get_cpu_var with __this_cpu_read if not used for an address.\n\n__get_cpu_var() can be replaced with this_cpu_read and will then use a\nsingle read instruction with implied address calculation to access the\ncorrect per cpu instance.\n\nHowever, the address of a per cpu variable passed to __this_cpu_read()\ncannot be determined (since it\u0027s an implied address conversion through\nsegment prefixes).  Therefore apply this only to uses of __get_cpu_var\nwhere the address of the variable is not used.\n\nCc: Pekka Enberg \u003cpenberg@cs.helsinki.fi\u003e\nCc: Hugh Dickins \u003chughd@google.com\u003e\nCc: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nAcked-by: H. Peter Anvin \u003chpa@zytor.com\u003e\nSigned-off-by: Christoph Lameter \u003ccl@linux.com\u003e\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\n"
    },
    {
      "commit": "2d999e03b7c8305b4385dd20992e4ed3e827177b",
      "tree": "3402eeb03a6cc7ac8013974983f09e46f5ecd562",
      "parents": [
        "29494be71afe2a16ad04e344306a620d7cc22d06"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Oct 20 12:06:18 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Nov 29 22:01:59 2010 -0800"
      },
      "message": "rcu: update documentation/comments for Lai\u0027s adoption patch\n\nLai\u0027s RCU-callback immediate-adoption patch changes the RCU tracing\noutput, so update tracing.txt.  Also update a few comments to clarify\nthe synchronization design.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "29494be71afe2a16ad04e344306a620d7cc22d06",
      "tree": "d16a2acd1566be326483d5217d39b78d2ef798c5",
      "parents": [
        "7b27d5475f86186914e54e4a6bb994e9a985337b"
      ],
      "author": {
        "name": "Lai Jiangshan",
        "email": "laijs@cn.fujitsu.com",
        "time": "Wed Oct 20 14:13:06 2010 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Nov 29 22:01:58 2010 -0800"
      },
      "message": "rcu,cleanup: simplify the code when cpu is dying\n\nWhen we handle the CPU_DYING notifier, the whole system is stopped except\nfor the current CPU.  We therefore need no synchronization with the other\nCPUs.  This allows us to move any orphaned RCU callbacks directly to the\nlist of any online CPU without needing to run them through the global\norphan lists.  These global orphan lists can therefore be dispensed with.\nThis commit makes thes changes, though currently victimizes CPU 0 @@@.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "4ee0a603926cad973e4d384f48c5e279a0fd4118",
      "tree": "da507192551987d4841fccc541a5b94adfef4f01",
      "parents": [
        "b0a0f667a349247bd7f05f806b662a25653822bc"
      ],
      "author": {
        "name": "Dongdong Deng",
        "email": "dongdong.deng@windriver.com",
        "time": "Tue Sep 28 16:32:43 2010 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Oct 07 10:41:06 2010 -0700"
      },
      "message": "rcu: using ACCESS_ONCE() to observe the jiffies_stall/rnp-\u003eqsmask value\n\nUsing ACCESS_ONCE() to observe the jiffies_stall/rnp-\u003eqsmask value\ndue to the caller didn\u0027t hold the root_rcu/rnp node\u0027s lock.  Although\nuse without ACCESS_ONCE() is safe due to the value loaded being used\nbut once, the ACCESS_ONCE() is a good documentation aid -- the variables\nare being loaded without the services of a lock.\n\nSigned-off-by: Dongdong Deng \u003cdongdong.deng@windriver.com\u003e\nCC: Dipankar Sarma \u003cdipankar@in.ibm.com\u003e\nCC: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "269dcc1c2ec25864308ee03a3fa26ea819d9f5d0",
      "tree": "1c81ee6a9151ab1580628f6e9f85c469ceccb5c0",
      "parents": [
        "0ddea0ead2ced99eaaaddff2beb755381e5c89f8"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Sep 07 14:23:09 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Sep 23 09:16:53 2010 -0700"
      },
      "message": "rcu: Add tracing data to support queueing models\n\nThe current tracing data is not sufficient to deduce the average time\nthat a callback spends waiting for a grace period to end.  Add three\nper-CPU counters recording the number of callbacks invoked (ci), the\nnumber of callbacks orphaned (co), and the number of callbacks adopted\n(ca).  Given the existing callback queue length (ql), the average wait\ntime in absence of CPU hotplug operations is ql/ci.  The units of wait\ntime will be in terms of the duration over which ci was measured.\n\nIn the presence of CPU hotplug operations, there is room for argument,\nbut ql/(ci-co+ca) won\u0027t steer you too far wrong.\n\nAlso fixes a typo called out by Lucas De Marchi \u003clucas.de.marchi@gmail.com\u003e.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "53d84e004d5e8c018be395c4330dc72fd60bd13e",
      "tree": "6d5b265442ac42c7cc73147b0de0d029644e312b",
      "parents": [
        "8cdd32a918350430483751feaae1c19cef816f69"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Aug 10 14:28:53 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Aug 20 09:00:12 2010 -0700"
      },
      "message": "rcu: permit suppressing current grace period\u0027s CPU stall warnings\n\nWhen using a kernel debugger, a long sojourn in the debugger can get\nyou lots of RCU CPU stall warnings once you resume.  This might not be\nhelpful, especially if you are using the system console.  This patch\ntherefore allows RCU CPU stall warnings to be suppressed, but only for\nthe duration of the current set of grace periods.\n\nThis differs from Jason\u0027s original patch in that it adds support for\ntiny RCU and preemptible RCU, and uses a slightly different method for\nsuppressing the RCU CPU stall warning messages.\n\nSigned-off-by: Jason Wessel \u003cjason.wessel@windriver.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nTested-by: Jason Wessel \u003cjason.wessel@windriver.com\u003e\n"
    },
    {
      "commit": "8cdd32a918350430483751feaae1c19cef816f69",
      "tree": "b219bf5daf42a5fa0b48caf8b94174be2aa9a63f",
      "parents": [
        "9079fd7c2e06a92cf27d05224a1f478581916c5b"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Aug 09 14:23:03 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Aug 20 09:00:11 2010 -0700"
      },
      "message": "rcu: refer RCU CPU stall-warning victims to stallwarn.txt\n\nThere is some documentation on RCU CPU stall warnings contained in\nDocumentation/RCU/stallwarn.txt, but it will not be apparent to someone\nwho runs into such a warning while under time pressure.  This commit\ntherefore adds comments preceding the printk()s pointing out the\nlocation of this documentation.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "910b1b7e19a292ff685001caf1bf1a9775b771a1",
      "tree": "7ec42bf018ab62c3c2180fbe168cd6130556cb80",
      "parents": [
        "687d7a960aea46e016182c7ce346d62c4dbd0366"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Jul 21 08:05:56 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Aug 19 17:18:04 2010 -0700"
      },
      "message": "rcu: Allow RCU CPU stall warnings to be off at boot, but manually enablable\n\nCurrently, if RCU CPU stall warnings are enabled, they are enabled\nimmediately upon boot.  They can be manually disabled via /sys (and\nalso re-enabled via /sys), and are automatically disabled upon panic.\nHowever, some users need RCU CPU stalls to be disabled at boot time,\nbut to be enabled without rebuilding/rebooting.  For example, someone\nrunning a real-time application in production might not want the\nadditional latency of RCU CPU stall detection in normal operation, but\nmight need to enable it at any point for fault isolation purposes.\n\nThis commit therefore provides a new CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE\nkernel configuration parameter that maintains the current behavior\n(enable at boot) by default, but allows a kernel to be configured\nwith RCU CPU stall detection built into the kernel, but disabled at\nboot time.\n\nRequested-by: Clark Williams \u003cwilliams@redhat.com\u003e\nRequested-by: John Kacur \u003cjkacur@redhat.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "f2e0dd7090eddef427ab9d9f81de122244cded51",
      "tree": "71f6dbc174eb9405c1d4313fafa2b5db369d5939",
      "parents": [
        "ded5e5ed2f3348ba2f9a319c6497e46c22850e97"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Jul 14 14:38:30 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Aug 19 17:18:03 2010 -0700"
      },
      "message": "rcu: allow RCU CPU stall warning messages to be controlled in /sys\n\nSet the permissions of the rcu_cpu_stall_suppress to 644 to enable RCU\nCPU stall warnings to be enabled and disabled at runtime via sysfs.\n\nSuggested-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "742734eea0cf5314cde5945963ed964be167bd84",
      "tree": "5716bb62b38f7c65099ff8bc3142457e60637eb3",
      "parents": [
        "b163760e37047781b37c412cde54d146ac4b651f"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Jun 30 11:43:52 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Aug 19 17:18:02 2010 -0700"
      },
      "message": "rcu: add boot parameter to suppress RCU CPU stall warning messages\n\nAlthough the RCU CPU stall warning messages are a very good way to alert\npeople to a problem, once alerted, it is sometimes helpful to shut them\noff in order to avoid obscuring other messages that might be being used\nto track down the problem.  Although you can rebuild the kernel with\nCONFIG_RCU_CPU_STALL_DETECTOR\u003dn, this is sometimes inconvenient.  This\ncommit therefore adds a boot parameter named \"rcu_cpu_stall_suppress\"\nthat shuts these messages off without requiring a rebuild (though a\nreboot might be needed for those not brave enough to patch their kernel\nwhile it is running).\n\nThis message-suppression was already in place for the panic case, so this\ncommit need only rename the variable and export it via module_param().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "394f99a9007d4274f7076bb8553ab0ff9707688b",
      "tree": "7d379f91321cec58b87fd5f5089947872689d591",
      "parents": [
        "e546f485e1d7520ca0200502cdcc11b503f4805c"
      ],
      "author": {
        "name": "Lai Jiangshan",
        "email": "laijs@cn.fujitsu.com",
        "time": "Mon Jun 28 16:25:04 2010 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Aug 19 17:18:01 2010 -0700"
      },
      "message": "rcu: simplify the usage of percpu data\n\n\u0026percpu_data is compatible with allocated percpu data.\n\nAnd we use it and remove the \"-\u003erda[NR_CPUS]\" array, saving significant\nstorage on systems with large numbers of CPUs.  This does add an additional\nlevel of indirection and thus an additional cache line referenced, but\nbecause -\u003erda is not used on the read side, this is OK.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nReviewed-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "551d55a944b143ef26fbd482d1c463199d6f65cf",
      "tree": "6911d3f8e8719ba5ca43c83acdf87cbc8276d7d1",
      "parents": [
        "875352c94224c88f5aa28cb77206f993bd31b7a2"
      ],
      "author": {
        "name": "Mathieu Desnoyers",
        "email": "mathieu.desnoyers@efficios.com",
        "time": "Sat Apr 17 08:48:42 2010 -0400"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jun 14 16:37:26 2010 -0700"
      },
      "message": "tree/tiny rcu: Add debug RCU head objects\n\nHelps finding racy users of call_rcu(), which results in hangs because list\nentries are overwritten and/or skipped.\n\nChangelog since v4:\n- Bissectability is now OK\n- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to\n  call_rcu(). Statically initialized objects are detected with\n  object_is_static().\n- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.\n- Remove init_rcu_head() completely.\n\nChangelog since v3:\n- Include comments from Lai Jiangshan\n\nThis new patch version is based on the debugobjects with the newly introduced\n\"active state\" tracker.\n\nNon-initialized entries are all considered as \"statically initialized\". An\nactivation fixup (triggered by call_rcu()) takes care of performing the debug\nobject initialization without issuing any warning. Since we cannot increase the\nsize of struct rcu_head, I don\u0027t see much room to put an identifier for\nstatically initialized rcu_head structures. So for now, we have to live without\n\"activation without explicit init\" detection. But the main purpose of this debug\noption is to detect double-activations (double call_rcu() use of a rcu_head\nbefore the callback is executed), which is correctly addressed here.\n\nThis also detects potential internal RCU callback corruption, which would cause\nthe callbacks to be executed twice.\n\nSigned-off-by: Mathieu Desnoyers \u003cmathieu.desnoyers@efficios.com\u003e\nCC: David S. Miller \u003cdavem@davemloft.net\u003e\nCC: \"Paul E. McKenney\" \u003cpaulmck@linux.vnet.ibm.com\u003e\nCC: akpm@linux-foundation.org\nCC: mingo@elte.hu\nCC: laijs@cn.fujitsu.com\nCC: dipankar@in.ibm.com\nCC: josh@joshtriplett.org\nCC: dvhltc@us.ibm.com\nCC: niv@us.ibm.com\nCC: tglx@linutronix.de\nCC: peterz@infradead.org\nCC: rostedt@goodmis.org\nCC: Valdis.Kletnieks@vt.edu\nCC: dhowells@redhat.com\nCC: eric.dumazet@gmail.com\nCC: Alexey Dobriyan \u003cadobriyan@gmail.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\n"
    },
    {
      "commit": "72d5a9f7a9542f88397558c65bcfc3b115a65e34",
      "tree": "e46d3ad1948de45b9641d1a8b88f88bfb3809007",
      "parents": [
        "4376030a54860dedab9d848dfa7cc700a6025c0b"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 17:12:17 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue May 11 16:10:47 2010 -0700"
      },
      "message": "rcu: remove all rcu head initializations, except on_stack initializations\n\nRemove all rcu head inits. We don\u0027t care about the RCU head state before passing\nit to call_rcu() anyway. Only leave the \"on_stack\" variants so debugobjects can\nkeep track of objects on stack.\n\nSigned-off-by: Mathieu Desnoyers \u003cmathieu.desnoyers@efficios.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "d21670acab9fcb4bc74a40b68a6941059234c55c",
      "tree": "6a4c054bc4dbadf0524b4e221889a8da558dbdaf",
      "parents": [
        "4a90a0681cf6cd21cd444184302aa045156486b3"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Apr 14 17:39:26 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:35 2010 -0700"
      },
      "message": "rcu: reduce the number of spurious RCU_SOFTIRQ invocations\n\nLai Jiangshan noted that up to 10% of the RCU_SOFTIRQ are spurious, and\ntraced this down to the fact that the current grace-period machinery\nwill uselessly raise RCU_SOFTIRQ when a given CPU needs to go through\na quiescent state, but has not yet done so.  In this situation, there\nmight well be nothing that RCU_SOFTIRQ can do, and the overhead can be\nworth worrying about in the ksoftirqd case.  This patch therefore avoids\nraising RCU_SOFTIRQ in this situation.\n\nChanges since v1 (http://lkml.org/lkml/2010/3/30/122 from Lai Jiangshan):\n\no\tOmit the rcu_qs_pending() prechecks, as they aren\u0027t that\n\tmuch less expensive than the quiescent-state checks.\n\no\tMerge with the set_need_resched() patch that reduces IPIs.\n\no\tAdd the new n_rp_report_qs field to the rcu_pending tracing output.\n\no\tUpdate the tracing documentation accordingly.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "4a90a0681cf6cd21cd444184302aa045156486b3",
      "tree": "5e54587e0844d51f6c015f4c489cbf021c9db509",
      "parents": [
        "4300aa642cc9ecb35f2e0683dd294fb790ef028c"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Apr 14 16:48:11 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:35 2010 -0700"
      },
      "message": "rcu: permit discontiguous cpu_possible_mask CPU numbering\n\nTREE_RCU assumes that CPU numbering is contiguous, but some users need\nlarge holes in the numbering to better map to hardware layout.  This patch\nmakes TREE_RCU (and TREE_PREEMPT_RCU) tolerate large holes in the CPU\nnumbering.  However, NR_CPUS must still be greater than the largest\nCPU number.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "4300aa642cc9ecb35f2e0683dd294fb790ef028c",
      "tree": "b70d676b02c6311a638fdaa6f3df8773b39fade1",
      "parents": [
        "26845c2860cebebe6ce2d9d01ae3cb3db84b7e29"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Apr 13 16:18:22 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:34 2010 -0700"
      },
      "message": "rcu: improve RCU CPU stall-warning messages\n\nThe existing RCU CPU stall-warning messages can be confusing, especially\nin the case where one CPU detects a single other stalled CPU.  In addition,\nthe console messages did not say which flavor of RCU detected the stall,\nwhich can make it difficult to work out exactly what is causing the stall.\nThis commit improves these messages.\n\nRequested-by: Dhaval Giani \u003cdhaval.giani@gmail.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "26845c2860cebebe6ce2d9d01ae3cb3db84b7e29",
      "tree": "83849948ea7bffb5e87eecc17a7275e357740632",
      "parents": [
        "c68de2097a8799549a3c3bf27cbfeea24a604284"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Apr 13 14:19:23 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:34 2010 -0700"
      },
      "message": "rcu: print boot-time console messages if RCU configs out of ordinary\n\nPrint boot-time messages if tracing is enabled, if fanout is set\nto non-default values, if exact fanout is specified, if accelerated\ndyntick-idle grace periods have been enabled, if RCU-lockdep is enabled,\nif rcutorture has been boot-time enabled, if the CPU stall detector has\nbeen disabled, or if four-level hierarchy has been enabled.\n\nThis is all for TREE_RCU and TREE_PREEMPT_RCU.  TINY_RCU will be handled\nseparately, if at all.\n\nSuggested-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "c68de2097a8799549a3c3bf27cbfeea24a604284",
      "tree": "acf2e5cb6de06185002a7d22daa91d893068551b",
      "parents": [
        "55ec936ff4e57cc626db336a7bf33b267390e9b4"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Apr 15 10:12:40 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:34 2010 -0700"
      },
      "message": "rcu: disable CPU stall warnings upon panic\n\nThe current RCU CPU stall warnings remain enabled even after a panic\noccurs, which some people have found to be a bit counterproductive.\nThis patch therefore uses a notifier to disable stall warnings once a\npanic occurs.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "bbad937983147c017c25406860287cb94da9af7c",
      "tree": "57311598c360b92b189c7ec337146e4bc779c73d",
      "parents": [
        "25502a6c13745f4650cc59322bd198194f55e796"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Apr 02 16:17:17 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:34 2010 -0700"
      },
      "message": "rcu: slim down rcutiny by removing rcu_scheduler_active and friends\n\nTINY_RCU does not need rcu_scheduler_active unless CONFIG_DEBUG_LOCK_ALLOC.\nSo conditionally compile rcu_scheduler_active in order to slim down\nrcutiny a bit more.  Also gets rid of an EXPORT_SYMBOL_GPL, which is\nresponsible for most of the slimming.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "25502a6c13745f4650cc59322bd198194f55e796",
      "tree": "d76cc659d3ea797c5da4630e219ac363d17c44a6",
      "parents": [
        "99652b54de1ee094236f7171485214071af4ef31"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Apr 01 17:37:01 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:33 2010 -0700"
      },
      "message": "rcu: refactor RCU\u0027s context-switch handling\n\nThe addition of preemptible RCU to treercu resulted in a bit of\nconfusion and inefficiency surrounding the handling of context switches\nfor RCU-sched and for RCU-preempt.  For RCU-sched, a context switch\nis a quiescent state, pure and simple, just like it always has been.\nFor RCU-preempt, a context switch is in no way a quiescent state, but\nspecial handling is required when a task blocks in an RCU read-side\ncritical section.\n\nHowever, the callout from the scheduler and the outer loop in ksoftirqd\nstill calls something named rcu_sched_qs(), whose name is no longer\naccurate.  Furthermore, when rcu_check_callbacks() notes an RCU-sched\nquiescent state, it ends up unnecessarily (though harmlessly, aside\nfrom the performance hit) enqueuing the current task if it happens to\nbe running in an RCU-preempt read-side critical section.  This not only\nincreases the maximum latency of scheduler_tick(), it also needlessly\nincreases the overhead of the next outermost rcu_read_unlock() invocation.\n\nThis patch addresses this situation by separating the notion of RCU\u0027s\ncontext-switch handling from that of RCU-sched\u0027s quiescent states.\nThe context-switch handling is covered by rcu_note_context_switch() in\ngeneral and by rcu_preempt_note_context_switch() for preemptible RCU.\nThis permits rcu_sched_qs() to handle quiescent states and only quiescent\nstates.  It also reduces the maximum latency of scheduler_tick(), though\nprobably by much less than a microsecond.  Finally, it means that tasks\nwithin preemptible-RCU read-side critical sections avoid incurring the\noverhead of queuing unless there really is a context switch.\n\nSuggested-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nAcked-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: Ingo Molnar \u003cmingo@elte.hu\u003e\nCc: Peter Zijlstra \u003cpeterz@infradead.org\u003e\n"
    },
    {
      "commit": "0c34029abdfdea64420cb4264c4e91a776b22157",
      "tree": "9025ccfef4210c04520617a4ae11ec4f24128660",
      "parents": [
        "f261414f0d56dd1a0e34888e27d1d4902ad052f3"
      ],
      "author": {
        "name": "Lai Jiangshan",
        "email": "laijs@cn.fujitsu.com",
        "time": "Sun Mar 28 11:12:30 2010 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:31 2010 -0700"
      },
      "message": "rcu: move some code from macro to function\n\nShrink the RCU_INIT_FLAVOR() macro by moving all but the initialization\nof the -\u003erda[] array to rcu_init_one().  The call to rcu_init_one()\ncan then be moved to the end of the RCU_INIT_FLAVOR() macro, which is\nrequired because rcu_boot_init_percpu_data(), which is now called from\nrcu_init_one(), depends on the initialization of the -\u003erda[] array.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "f261414f0d56dd1a0e34888e27d1d4902ad052f3",
      "tree": "6779e82e0a520121a8d1b86fbfb248bef3ab201a",
      "parents": [
        "d25eb9442bb2c38c1e742f0fa764d7132d72593f"
      ],
      "author": {
        "name": "Lai Jiangshan",
        "email": "laijs@cn.fujitsu.com",
        "time": "Sun Mar 28 11:15:20 2010 +0800"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:31 2010 -0700"
      },
      "message": "rcu: make dead code really dead\n\ncleanup: make dead code really dead\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "d25eb9442bb2c38c1e742f0fa764d7132d72593f",
      "tree": "0a2604a3b61ce7a0868c021ac945d9826e0d88f1",
      "parents": [
        "2b3fc35f6919344e3cf722dde8308f47235c0b70"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Mar 18 21:36:51 2010 -0700"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon May 10 11:08:31 2010 -0700"
      },
      "message": "rcu: substitute set_need_resched for sending resched IPIs\n\nThis patch adds a check to __rcu_pending() that does a local\nset_need_resched() if the current CPU is holding up the current grace\nperiod and if force_quiescent_state() will be called soon.  The goal is\nto reduce the probability that force_quiescent_state() will need to do\nsmp_send_reschedule(), which sends an IPI and is therefore more expensive\non most architectures.\n\nSigned-off-by: \"Paul E. McKenney\" \u003cpaulmck@linux.vnet.ibm.com\u003e\n"
    },
    {
      "commit": "a47cd880b50e14b0b6f5e9d426ae9a2676c9c474",
      "tree": "c134dcec52450ec92ea853f4aeeef8e3967a36cb",
      "parents": [
        "f5f654096487c6d526c47bb66308f9de81f091cf"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Feb 26 16:38:56 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat Feb 27 09:53:52 2010 +0100"
      },
      "message": "rcu: Fix accelerated grace periods for last non-dynticked CPU\n\nIt is invalid to invoke __rcu_process_callbacks() with irqs\ndisabled, so do it indirectly via raise_softirq().  This\nrequires a state-machine implementation to cycle through the\ngrace-period machinery the required number of times.\n\nLocated-by: Ingo Molnar \u003cmingo@elte.hu\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1267231138-27856-1-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "d9f1bb6ad7fc53c406706f47858dd5ff030b14a3",
      "tree": "4af519d68b396e372e6a5afbb5e968de3bacd123",
      "parents": [
        "056ba4a9bea5f32781a36b797c562fb731e5eaa6"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Feb 25 14:06:47 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Fri Feb 26 08:20:46 2010 +0100"
      },
      "message": "rcu: Make rcu_read_lock_sched_held() take boot time into account\n\nBefore the scheduler starts, all tasks are non-preemptible by\ndefinition. So, during that time, rcu_read_lock_sched_held()\nneeds to always return \"true\".  This patch makes that be so.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1267135607-7056-2-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "1ed509a225008c9e8c0644fbd22168e09a7383a0",
      "tree": "db65a58258bb968e7bc922dab14f4f0714a7667e",
      "parents": [
        "6155fec92e85f07d99e9746234496215443ffb0d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Feb 22 17:05:05 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Feb 25 10:35:02 2010 +0100"
      },
      "message": "rcu: Add RCU_CPU_STALL_VERBOSE to dump detailed per-task information\n\nWhen RCU detects a grace-period stall, it currently just prints\nout the PID of any tasks doing the stalling.  This patch adds\nRCU_CPU_STALL_VERBOSE, which enables the more-verbose reporting\nfrom sched_show_task().\n\nSuggested-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-21-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "3acd9eb31c5f7eb97cb2009fa41472710fb4a10f",
      "tree": "a339775ed9683bdf0f4d7b47a75648a6f86a8446",
      "parents": [
        "1304afb225288a2e250d6a7495462c28e5509cbb"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Feb 22 17:05:03 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Feb 25 10:34:59 2010 +0100"
      },
      "message": "rcu: Fix deadlock in TREE_PREEMPT_RCU CPU stall detection\n\nUnder TREE_PREEMPT_RCU, print_other_cpu_stall() invokes\nrcu_print_task_stall() with the root rcu_node structure\u0027s -\u003elock\nheld, and rcu_print_task_stall() acquires that same lock for\nself-deadlock. Fix this by removing the lock acquisition from\nrcu_print_task_stall(), and making all callers acquire the lock\ninstead.\n\nTested-by: John Kacur \u003cjkacur@redhat.com\u003e\nTested-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nLocated-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-19-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "1304afb225288a2e250d6a7495462c28e5509cbb",
      "tree": "1ba76e304f718f7ce89532e1c4d276b4af439c07",
      "parents": [
        "20133cfce7d0bbdcc0c398301030c091f5675c88"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Feb 22 17:05:02 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Feb 25 10:34:58 2010 +0100"
      },
      "message": "rcu: Convert to raw_spinlocks\n\nThe spinlocks in rcutree need to be real spinlocks in\npreempt-rt. Convert them to raw_spinlocks.\n\nSigned-off-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-18-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "20133cfce7d0bbdcc0c398301030c091f5675c88",
      "tree": "337f242bfc89f5880cf86234fa6b574f52a2f0a5",
      "parents": [
        "1bd22e374b20c2f0ba1d2723c1f585acab2251c5"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Feb 22 17:05:01 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Feb 25 10:34:57 2010 +0100"
      },
      "message": "rcu: Stop overflowing signed integers\n\nThe C standard does not specify the result of an operation that\noverflows a signed integer, so such operations need to be\navoided.  This patch changes the type of several fields from\n\"long\" to \"unsigned long\" and adjusts operations as needed.\nULONG_CMP_GE() and ULONG_CMP_LT() macros are introduced to do\nthe modular comparisons that are appropriate given that overflow\nis an expected event.\n\nAcked-by: Mathieu Desnoyers \u003cmathieu.desnoyers@efficios.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-17-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "8bd93a2c5d4cab2ae17d06350daa7dbf546a4634",
      "tree": "3facbdbfbcc1b169fad20f456b0a2521adadfb25",
      "parents": [
        "998f2ac3fea93bfa8b55c279fff68f7c5b9ab93d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Feb 22 17:04:59 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Feb 25 10:34:55 2010 +0100"
      },
      "message": "rcu: Accelerate grace period if last non-dynticked CPU\n\nCurrently, rcu_needs_cpu() simply checks whether the current CPU\nhas an outstanding RCU callback, which means that the last CPU\nto go into dyntick-idle mode might wait a few ticks for the\nrelevant grace periods to complete.  However, if all the other\nCPUs are in dyntick-idle mode, and if this CPU is in a quiescent\nstate (which it is for RCU-bh and RCU-sched any time that we are\nconsidering going into dyntick-idle mode), then the grace period\nis instantly complete.\n\nThis patch therefore repeatedly invokes the RCU grace-period\nmachinery in order to force any needed grace periods to complete\nquickly.  It does so a limited number of times in order to\nprevent starvation by an RCU callback function that might pass\nitself to call_rcu().\n\nHowever, if any CPU other than the current one is not in\ndyntick-idle mode, fall back to simply checking (with fix to bug\nnoted by Lai Jiangshan).  Also, take advantage of last\ngrace-period forcing, the opportunity to do so noted by Steve\nRostedt.  And apply simplified #ifdef condition suggested by\nFrederic Weisbecker.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-15-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "017c426138122c8e9b9f5057fbd0567c37b35247",
      "tree": "648d35f773bc08e83d06f0c02a68cae02c46a4cd",
      "parents": [
        "4c54005ca438a8b46dd542b497d4f0dc2ca375e8"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Jan 14 16:10:58 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat Jan 16 10:25:22 2010 +0100"
      },
      "message": "rcu: Fix sparse warnings\n\nRename local variable \"i\" in rcu_init() to avoid conflict with\nRCU_INIT_FLAVOR(), restrict the scope of RCU_TREE_NONCORE, and\nmake __synchronize_srcu() static.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12635142581560-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "b6407e863934965cdc66cbc244d811ceeb6f4d77",
      "tree": "5fb8f9fe233a2084f283887e019e6bf5ac6fac29",
      "parents": [
        "cba8244a0f1c277b6b1e48ed6504fa434119e24d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 16:04:02 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:07 2010 +0100"
      },
      "message": "rcu: Give different levels of the rcu_node hierarchy distinct lockdep names\n\nPreviously, each level of the rcu_node hierarchy had the same\nrather unimaginative name: \"\u0026rcu_node_class[i]\".  This makes\nlockdep diagnostics involving these lockdep classes less helpful\nthan would be nice. This patch fixes this by giving each level\nof the rcu_node hierarchy a distinct name: \"rcu_node_level_0\",\n\"rcu_node_level_1\", and so on. This version of the patch\nincludes improved diagnostics suggested by Josh Triplett and\nPeter Zijlstra.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626498421830-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "bf66f18e79e34c421bbd8f6511e2c556b779df2f",
      "tree": "2348e3bc8392addf7959fbe94003f7e0da2a1c8b",
      "parents": [
        "46a1e34eda805501a8b32f26394faa435149f6d1"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:10 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:05 2010 +0100"
      },
      "message": "rcu: Add force_quiescent_state() testing to rcutorture\n\nAdd force_quiescent_state() testing to rcutorture, with a\nseparate thread that repeatedly invokes force_quiescent_state()\nin bursts. This can greatly increase the probability of\nencountering certain types of race conditions.\n\nSuggested-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1262646551116-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "46a1e34eda805501a8b32f26394faa435149f6d1",
      "tree": "56359434e348fce6ffc8701fb4948dee1cb4c91f",
      "parents": [
        "45f014c52eef022873b19d6a20eb0ec9668f2b09"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:09 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:05 2010 +0100"
      },
      "message": "rcu: Make force_quiescent_state() start grace period if needed\n\nGrace periods cannot be started while force_quiescent_state() is\nactive.  This is OK in that the affected CPUs will try again\nlater, but it does induce needless grace-period delays.  This\npatch causes rcu_start_gp() to record a failed attempt to start\na grace period. When force_quiescent_state() prepares to return,\nit then starts the grace period if there was such a failed\nattempt.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501854-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "45f014c52eef022873b19d6a20eb0ec9668f2b09",
      "tree": "036e3987276a5e689869a47b3641d70588db2489",
      "parents": [
        "ee47eb9f4da6f44af965d6d049e77ee8c8a4b822"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:08 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:04 2010 +0100"
      },
      "message": "rcu: Remove redundant grace-period check\n\nThe rcu_process_dyntick() function checks twice for the end of\nthe current grace period.  However, it holds the current\nrcu_node structure\u0027s -\u003elock field throughout, and doesn\u0027t get to\nthe second call to rcu_gp_in_progress() unless there is at least\none CPU corresponding to this rcu_node structure that has not\nyet checked in for the current grace period, which would prevent\nthe current grace period from ending. So the current grace\nperiod cannot have ended, and the second check is redundant, so\nremove it.\n\nAlso, given that this function is used even with !CONFIG_NO_HZ,\nits name is quite misleading.  Change from rcu_process_dyntick()\nto force_qs_rnp().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1262646550562-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "ee47eb9f4da6f44af965d6d049e77ee8c8a4b822",
      "tree": "bc500b12150bd47afd34b24fd1db90939f5fec3b",
      "parents": [
        "0f10dc826646134dce3e5751512b87d30f3903e4"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:07 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:04 2010 +0100"
      },
      "message": "rcu: Remove leg of force_quiescent_state() switch statement\n\nThe comparisons of rsp-\u003egpnum nad rsp-\u003ecompleted in\nrcu_process_dyntick() and force_quiescent_state() can be\nreplaced by the much more clear rcu_gp_in_progress() predicate\nfunction.  After doing this, it becomes clear that the\nRCU_SAVE_COMPLETED leg of the force_quiescent_state() function\u0027s\nswitch statement is almost completely a no-op.  A small change\nto the RCU_SAVE_DYNTICK leg renders it a complete no-op, after\nwhich it can be removed.  Doing so also eliminates the forcenow\nlocal variable from force_quiescent_state().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501781-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "0f10dc826646134dce3e5751512b87d30f3903e4",
      "tree": "6d377b3714889a0ab148166a33105b3be14be0c1",
      "parents": [
        "eb1ba45f1e7f6e626fefc063b340c7cbec9bd8c7"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:06 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:03 2010 +0100"
      },
      "message": "rcu: Eliminate rcu_process_dyntick() return value\n\nBecause a new grace period cannot start while we are executing\nwithin the force_quiescent_state() function\u0027s switch statement,\nif any test within that switch statement or within any function\ncalled from that switch statement shows that the current grace\nperiod has ended, we can safely re-do that test any time before\nwe leave the switch statement.  This means that we no longer\nneed a return value from rcu_process_dyntick(), as we can simply\ninvoke rcu_gp_in_progress() to check whether the old grace\nperiod has finished -- there is no longer any need to worry\nabout whether or not a new grace period has been started.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501857-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "eb1ba45f1e7f6e626fefc063b340c7cbec9bd8c7",
      "tree": "e5d37e450c3c2c96863060c9a7b51a90c03fe363",
      "parents": [
        "39c0bbfc07c6e28db7346d0e11106f2d045d3035"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:05 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:03 2010 +0100"
      },
      "message": "rcu: Eliminate second argument of rcu_process_dyntick()\n\nAt this point, the second argument to all calls to\nrcu_process_dyntick() is a function of the same field of the\nstructure passed in as the first argument, namely, rsp-\u003egpnum-1.\n So propagate rsp-\u003egpnum-1 to all uses of the second argument\nwithin rcu_process_dyntick() and then eliminate the second\nargument.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465503786-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "39c0bbfc07c6e28db7346d0e11106f2d045d3035",
      "tree": "82f0fdacb1eea0334e76e0adb8b9d5beec66f2a7",
      "parents": [
        "f3a8b5c6aa543bd87764418d63632eb65b80e2f6"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:04 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:03 2010 +0100"
      },
      "message": "rcu: Eliminate local variable lastcomp from force_quiescent_state()\n\nBecause rsp-\u003efqs_active is set to 1 across\nforce_quiescent_state()\u0027s switch statement, rcu_start_gp() will\nrefrain from starting a new grace period during this time.\nTherefore, rsp-\u003egpnum is constant, and can be propagated to all\nuses of lastcomp, eliminating this local variable.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465502985-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "f3a8b5c6aa543bd87764418d63632eb65b80e2f6",
      "tree": "c579ced57838ee4f0504c5c295d283b37636e747",
      "parents": [
        "07079d5357a4d53c2b13126c4a38fb40e6e04966"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:03 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:02 2010 +0100"
      },
      "message": "rcu: Eliminate local variable signaled from force_quiescent_state()\n\nBecause the root rcu_node lock is held across entry to the\nswitch statement in force_quiescent_state(), it is no longer\nnecessary to snapshot rsp-\u003esignaled to a local variable.\nEliminate both the snapshotting and the local variable.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1262646550602-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "07079d5357a4d53c2b13126c4a38fb40e6e04966",
      "tree": "1a97552a220a9bbdfceb1cda01c1ee5b92ce75bd",
      "parents": [
        "559569acf94f538b56bd6eead80b439d6a78cdff"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:02 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:02 2010 +0100"
      },
      "message": "rcu: Prohibit starting new grace periods while forcing quiescent states\n\nReduce the number and variety of race conditions by prohibiting\nthe start of a new grace period while force_quiescent_state() is\nactive. A new fqs_active flag in the rcu_state structure is used\nto trace whether or not force_quiescent_state() is active, and\nthis new flag is tested by rcu_start_gp().  If the CPU that\nclosed out the last grace period needs another grace period,\nthis new grace period may be delayed up to one scheduling-clock\ntick, but it will eventually get started.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c126264655052-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "559569acf94f538b56bd6eead80b439d6a78cdff",
      "tree": "36ff850b4bfd45cdeb102092f4cf00c48ca86434",
      "parents": [
        "f96e9232e04856c781d4f71923a46dd3f7b429fa"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:01 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:01 2010 +0100"
      },
      "message": "rcu: Adjust force_quiescent_state() locking, step 2\n\nThis patch releases rnp-\u003elock after the end of\nforce_quiescent_state()\u0027s switch statement.  This is a second\nstep towards prohibiting starting grace periods while\nforce_quiescent_state() is executing, which will reduce the\nnumber and complexity of races that force_quiescent_state() is\ninvolved in.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501994-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "f96e9232e04856c781d4f71923a46dd3f7b429fa",
      "tree": "3c320a0a2bc03f54fea5c115b6c0fa1e4bcc7e27",
      "parents": [
        "7284ce6c9f6153d1777df5f310c959724d1bd446"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Jan 04 15:09:00 2010 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Wed Jan 13 09:06:01 2010 +0100"
      },
      "message": "rcu: Adjust force_quiescent_state() locking, step 1\n\nThis causes rnp-\u003elock to be held on entry to\nforce_quiescent_state()\u0027s switch statement.  This is a first\nstep towards prohibiting starting grace periods while\nforce_quiescent_state() is executing, which will reduce the\nnumber and complexity of races that force_quiescent_state() is\ninvolved in.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501455-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "d9a3da0699b24a589b27a61e1a5b5bd30d9db669",
      "tree": "f7440e396a6c818f3cef514ccc31ab55d88025ef",
      "parents": [
        "cf244dc01bf68e1ad338b82447f8686d24ea4435"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Dec 02 12:10:15 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Dec 03 11:35:25 2009 +0100"
      },
      "message": "rcu: Add expedited grace-period support for preemptible RCU\n\nImplement an synchronize_rcu_expedited() for preemptible RCU\nthat actually is expedited.  This uses\nsynchronize_sched_expedited() to force all threads currently\nrunning in a preemptible-RCU read-side critical section onto the\nappropriate -\u003eblocked_tasks[] list, then takes a snapshot of all\nof these lists and waits for them to drain.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1259784616158-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "cf244dc01bf68e1ad338b82447f8686d24ea4435",
      "tree": "dc2aebb60ef1eddf92d7e23b72ec2f6c08797684",
      "parents": [
        "d3f6bad3911736e44ba11f3f3f6ac4e8c837fdfc"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Dec 02 12:10:14 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Dec 03 11:34:53 2009 +0100"
      },
      "message": "rcu: Enable fourth level of TREE_RCU hierarchy\n\nEnable a fourth level of rcu_node hierarchy for TREE_RCU and\nTREE_PREEMPT_RCU.  This is for stress-testing and experiemental\npurposes only, although in theory this would enable 16,777,216\nCPUs on 64-bit systems, though only 1,048,576 CPUs on 32-bit\nsystems. Normal experimental use of this fourth level will\nnormally set CONFIG_RCU_FANOUT\u003d2, requiring a 16-CPU system,\nthough the more adventurous (and more fortunate) experimenters\nmay wish to chose CONFIG_RCU_FANOUT\u003d3 for 81-CPU systems or even\nCONFIG_RCU_FANOUT\u003d4 for 256-CPU systems.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nAcked-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12597846161257-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "d3f6bad3911736e44ba11f3f3f6ac4e8c837fdfc",
      "tree": "55b0c2e11ab3ec02e9065cf3d46ffd20386dfed2",
      "parents": [
        "6ebb237bece23275d1da149b61a342f0d4d06a08"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Wed Dec 02 12:10:13 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Thu Dec 03 11:34:26 2009 +0100"
      },
      "message": "rcu: Rename \"quiet\" functions\n\nThe number of \"quiet\" functions has grown recently, and the\nnames are no longer very descriptive.  The point of all of these\nfunctions is to do some portion of the task of reporting a\nquiescent state, so rename them accordingly:\n\no\tcpu_quiet() becomes rcu_report_qs_rdp(), which reports a\n\tquiescent state to the per-CPU rcu_data structure.  If this\n\tturns out to be a new quiescent state for this grace period,\n\tthen rcu_report_qs_rnp() will be invoked to propagate the\n\tquiescent state up the rcu_node hierarchy.\n\no\tcpu_quiet_msk() becomes rcu_report_qs_rnp(), which reports\n\ta quiescent state for a given CPU (or possibly a set of CPUs)\n\tup the rcu_node hierarchy.\n\no\tcpu_quiet_msk_finish() becomes rcu_report_qs_rsp(), which\n\treports a full set of quiescent states to the global rcu_state\n\tstructure.\n\no\ttask_quiet() becomes rcu_report_unblock_qs_rnp(), which reports\n\ta quiescent state due to a task exiting an RCU read-side critical\n\tsection that had previously blocked in that same critical section.\n\tAs indicated by the new name, this type of quiescent state is\n\treported up the rcu_node hierarchy (using rcu_report_qs_rnp()\n\tto do so).\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nAcked-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12597846163698-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "6ebb237bece23275d1da149b61a342f0d4d06a08",
      "tree": "5f3d99f6ce2e1e98736e5708eecb5bf217f78fde",
      "parents": [
        "9f680ab41485edfdc96331b70afa7513aa0a7720"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Sun Nov 22 08:53:50 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sun Nov 22 18:58:16 2009 +0100"
      },
      "message": "rcu: Re-arrange code to reduce #ifdef pain\n\nRemove #ifdefs from kernel/rcupdate.c and\ninclude/linux/rcupdate.h by moving code to\ninclude/linux/rcutiny.h, include/linux/rcutree.h, and\nkernel/rcutree.c.\n\nAlso remove some definitions that are no longer used.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1258908830885-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "9f680ab41485edfdc96331b70afa7513aa0a7720",
      "tree": "620b34f8129c0ea4ddee033c9875a9f60bfba2ae",
      "parents": [
        "b668c9cf3e58739dac54a1d6f42f2b4bdd980b3e"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Sun Nov 22 08:53:49 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sun Nov 22 18:58:16 2009 +0100"
      },
      "message": "rcu: Eliminate unneeded function wrapping\n\nThe functions rcu_init() is a wrapper for __rcu_init(), and also\nsets up the CPU-hotplug notifier for rcu_barrier_cpu_hotplug().\nBut TINY_RCU doesn\u0027t need CPU-hotplug notification, and the\nrcu_barrier_cpu_hotplug() is a simple wrapper for\nrcu_cpu_notify().\n\nSo push rcu_init() out to kernel/rcutree.c and kernel/rcutiny.c\nand get rid of the wrapper function rcu_barrier_cpu_hotplug().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12589088302320-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "b668c9cf3e58739dac54a1d6f42f2b4bdd980b3e",
      "tree": "c0165d39532a2314f8187d765f3c8ddf88b72831",
      "parents": [
        "2f51f9884f6a36b0fe9636d5a1937e5cbd25723b"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Sun Nov 22 08:53:48 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sun Nov 22 18:58:15 2009 +0100"
      },
      "message": "rcu: Fix grace-period-stall bug on large systems with CPU hotplug\n\nWhen the last CPU of a given leaf rcu_node structure goes\noffline, all of the tasks queued on that leaf rcu_node structure\n(due to having blocked in their current RCU read-side critical\nsections) are requeued onto the root rcu_node structure.  This\nrequeuing is carried out by rcu_preempt_offline_tasks().\nHowever, it is possible that these queued tasks are the only\nthing preventing the leaf rcu_node structure from reporting a\nquiescent state up the rcu_node hierarchy.  Unfortunately, the\nold code would fail to do this reporting, resulting in a\ngrace-period stall given the following sequence of events:\n\n1.\tKernel built for more than 32 CPUs on 32-bit systems or for more\n\tthan 64 CPUs on 64-bit systems, so that there is more than one\n\trcu_node structure.  (Or CONFIG_RCU_FANOUT is artificially set\n\tto a number smaller than CONFIG_NR_CPUS.)\n\n2.\tThe kernel is built with CONFIG_TREE_PREEMPT_RCU.\n\n3.\tA task running on a CPU associated with a given leaf rcu_node\n\tstructure blocks while in an RCU read-side critical section\n\t-and- that CPU has not yet passed through a quiescent state\n\tfor the current RCU grace period.  This will cause the task\n\tto be queued on the leaf rcu_node\u0027s blocked_tasks[] array, in\n\tparticular, on the element of this array corresponding to the\n\tcurrent grace period.\n\n4.\tEach of the remaining CPUs corresponding to this same leaf rcu_node\n\tstructure pass through a quiescent state.  However, the task is\n\tstill in its RCU read-side critical section, so these quiescent\n\tstates cannot be reported further up the rcu_node hierarchy.\n\tNevertheless, all bits in the leaf rcu_node structure\u0027s -\u003eqsmask\n\tfield are now zero.\n\n5.\tEach of the remaining CPUs go offline.  (The events in step\n\t#4 and #5 can happen in any order as long as each CPU passes\n\tthrough a quiescent state before going offline.)\n\n6.\tWhen the last CPU goes offline, __rcu_offline_cpu() will invoke\n\trcu_preempt_offline_tasks(), which will move the task to the\n\troot rcu_node structure, but without reporting a quiescent state\n\tup the rcu_node hierarchy (and this failure to report a quiescent\n\tstate is the bug).\n\n\tBut because this leaf rcu_node structure\u0027s -\u003eqsmask field is\n\talready zero and its -\u003eblock_tasks[] entries are all empty,\n\tforce_quiescent_state() will skip this rcu_node structure.\n\n\tTherefore, grace periods are now hung.\n\nThis patch abstracts some code out of rcu_read_unlock_special(),\ncalling the result task_quiet() by analogy with cpu_quiet(), and\ninvokes task_quiet() from both rcu_read_lock_special() and\n__rcu_offline_cpu().  Invoking task_quiet() from\n__rcu_offline_cpu() reports the quiescent state up the rcu_node\nhierarchy, fixing the bug.  This ends up requiring a separate\nlock_class_key per level of the rcu_node hierarchy, which this\npatch also provides.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12589088301770-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "2f51f9884f6a36b0fe9636d5a1937e5cbd25723b",
      "tree": "0505e111a9714b2bd022322f76e6c4de26861107",
      "parents": [
        "560d4bc0df9a5e63b980432282d8c2bd3559ec74"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Nov 13 19:51:39 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat Nov 14 10:31:42 2009 +0100"
      },
      "message": "rcu: Eliminate __rcu_pending() false positives\n\nNow that there are both -\u003egpnum and -\u003ecompleted fields in the\nrcu_node structure, __rcu_pending() should check rdp-\u003egpnum and\nrdp-\u003ecompleted against rnp-\u003egpnum and rdp-\u003ecompleted, respectively,\ninstead of the prior comparison against the rcu_state fields\nrsp-\u003egpnum and rsp-\u003ecompleted.\n\nGiven the old comparison, __rcu_pending() could return 1, resulting\nin a needless raise_softirq(RCU_SOFTIRQ).  This useless work would\nhappen if RCU responded to a scheduling-clock interrupt after the\nrcu_state fields had been updated, but before the rcu_node fields\nhad been updated.\n\nChanging the comparison from the rcu_state fields to the rcu_node\nfields prevents this useless work from happening.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12581706991966-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "560d4bc0df9a5e63b980432282d8c2bd3559ec74",
      "tree": "1e44bf34973b217977d0b4d57d2b1ee1d4209f08",
      "parents": [
        "8e9aa8f067d2dcd9457980ced618e1cffbcfba46"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Fri Nov 13 19:51:38 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Sat Nov 14 10:31:42 2009 +0100"
      },
      "message": "rcu: Further cleanups of use of lastcomp\n\nNow that a copy of the rsp-\u003ecompleted flag is available in all\nrcu_node structures, make full use of it.  It is still\nlegitimate to access rsp-\u003ecompleted while holding the root\nrcu_node structure\u0027s lock, however.\n\nAlso, tighten up force_quiescent_state()\u0027s checks for end of\ncurrent grace period.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1258170699933-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "8e9aa8f067d2dcd9457980ced618e1cffbcfba46",
      "tree": "bb32427c6a010435420e4b9481d2fdf1961fdc17",
      "parents": [
        "b32e9eb6ad29572b4451847d0e8227c9be2b6d69"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Nov 12 22:35:04 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Fri Nov 13 10:18:36 2009 +0100"
      },
      "message": "rcu: Simplify association of forced quiescent states with grace periods\n\nThe force_quiescent_state() function also took a snapshot\nof the -\u003ecompleted field, which was as obnoxious as it was in\nrcu_sched_qs() and friends.  So snapshot -\u003egpnum-1.\n\nAlso, since the dyntick_record_completed() and\ndyntick_recall_completed() functions are now simple assignments\nthat are independent of CONFIG_NO_HZ, and since their names are\nnow misleading, get rid of them.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12580941042308-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "b32e9eb6ad29572b4451847d0e8227c9be2b6d69",
      "tree": "d697f2c9dcf59d2defb6693866bf33cc45307dca",
      "parents": [
        "0e0fc1c23e04c15e814763f2b366e92d87d8b95d"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Nov 12 22:35:03 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Fri Nov 13 10:18:36 2009 +0100"
      },
      "message": "rcu: Accelerate callback processing on CPUs not detecting GP end\n\nAn earlier fix for a race resulted in a situation where the CPUs\nother than the CPU that detected the end of the grace period would\nnot process their callbacks until the next grace period started.\n\nThis means that these other CPUs would unnecessarily demand that an\nextra grace period be started.\n\nThis patch eliminates this extra grace period and speeds callback\nprocessing by propagating rsp-\u003ecompleted to the rcu_node structures\nin the case where the CPU detecting the end of the grace period\nsees no reason to start a new grace period.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1258094104417-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "c64ac3ce06558e534aec62b1fadeb0a3f111dac1",
      "tree": "faee8cf2d5cb47aeac4999a1e2163491a8e03734",
      "parents": [
        "4bcfe055030d9e953945def3864f7e6997b27782"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Nov 10 13:37:22 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 22:48:50 2009 +0100"
      },
      "message": "rcu: Simplify association of quiescent states with grace periods\n\nThe rdp-\u003epassed_quiesc_completed fields are used to properly\nassociate the recorded quiescent state with a grace period.  It\nis OK to wrongly associate a given quiescent state with a\npreceding grace period, but it is fatal to associate a given\nquiescent state with a grace period that begins after the\nquiescent state occurred.  Grace periods are numbered, and the\nfollowing fields track them:\n\no\t-\u003egpnum is the number of the grace period currently in\n\tprogress, or the number of the last grace period to\n\tcomplete if no grace period is currently in progress.\n\no\t-\u003ecompleted is the number of the last grace period to\n\thave completed.\n\nThese two fields are equal if there is no grace period in\nprogress, otherwise -\u003egpnum is one greater than -\u003ecompleted.\nBut the rdp-\u003epassed_quiesc_completed field compared against\n-\u003ecompleted, and if equal, the quiescent state is presumed to\ncount against the current grace period.\n\nThe earlier code copied rdp-\u003ecompleted to\nrdp-\u003epassed_quiesc_completed, which has been made to work, but\nis error-prone.  In contrast, copying one less than rdp-\u003egpnum\nis guaranteed safe, because rdp-\u003egpnum is not incremented until\nafter the start of the corresponding grace period. At the end of\nthe grace period, when -\u003ecompleted has incremented, then any\nquiescent periods recorded previously will be discarded.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12578890421011-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "4bcfe055030d9e953945def3864f7e6997b27782",
      "tree": "5021112c826572bd0b356f193c2be742e54deb4f",
      "parents": [
        "956539b75921f561c0956c22d37320780e8b4ba1"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Tue Nov 10 13:37:21 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 22:48:50 2009 +0100"
      },
      "message": "rcu: Rename dynticks_completed to completed_fqs\n\nThis field is used whether or not CONFIG_NO_HZ is set, so the\nold name of -\u003edynticks_completed is quite misleading.\n\nChange to -\u003ecompleted_fqs, given that it the value that\nforce_quiescent_state() is trying to drive the -\u003ecompleted field\naway from.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12578890423298-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "9160306e6f5b68bb64630c9031c517ca1cf463db",
      "tree": "d8f78f99d417f34121c21e45a4675b2b1d5c2674",
      "parents": [
        "d09b62dfa336447c52a5ec9bb88adbc479b0f3b8"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Nov 02 13:52:29 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 04:12:11 2009 +0100"
      },
      "message": "rcu: Fix note_new_gpnum() uses of -\u003egpnum\n\nImpose a clear locking design on the note_new_gpnum()\nfunction\u0027s use of the -\u003egpnum counter.  This is done by updating\nrdp-\u003egpnum only from the corresponding leaf rcu_node structure\u0027s\nrnp-\u003egpnum field, and even then only under the protection of\nthat same rcu_node structure\u0027s -\u003elock field.  Performance and\nscalability are maintained using a form of double-checked\nlocking, and excessive spinning is avoided by use of the\nspin_trylock() function.  The use of spin_trylock() is safe due\nto the fact that CPUs who fail to acquire this lock will try\nagain later. The hierarchical nature of the rcu_node data\nstructure limits contention (which could be limited further if\nneed be using the RCU_FANOUT kernel parameter).\n\nWithout this patch, obscure but quite possible races could\nresult in a quiescent state that occurred during one grace\nperiod to be accounted to the following grace period, causing\nthis following grace period to end prematurely.  Not good!\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: \u003cstable@kernel.org\u003e # .32.x\nLKML-Reference: \u003c12571987492350-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "d09b62dfa336447c52a5ec9bb88adbc479b0f3b8",
      "tree": "70a002fed2e0471def01ea3c166137449cb1527d",
      "parents": [
        "281d150c5f8892f158747594ab49ce2823fd8b8c"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Nov 02 13:52:28 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 04:11:54 2009 +0100"
      },
      "message": "rcu: Fix synchronization for rcu_process_gp_end() uses of -\u003ecompleted counter\n\nImpose a clear locking design on the rcu_process_gp_end()\nfunction\u0027s use of the -\u003ecompleted counter.  This is done by\ncreating a -\u003ecompleted field in the rcu_node structure, which\ncan safely be accessed under the protection of that structure\u0027s\nlock.  Performance and scalability are maintained by using a\nform of double-checked locking, so that rcu_process_gp_end()\nonly acquires the leaf rcu_node structure\u0027s -\u003elock if a grace\nperiod has recently ended.\n\nThis fix reduces rcutorture failure rate by at least two orders\nof magnitude under heavy stress with force_quiescent_state()\nbeing invoked artificially often.  Without this fix,\nunsynchronized access to the -\u003ecompleted field can cause\nrcu_process_gp_end() to advance callbacks whose grace period has\nnot yet expired.  (Bad idea!)\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: \u003cstable@kernel.org\u003e # .32.x\nLKML-Reference: \u003c12571987494069-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "281d150c5f8892f158747594ab49ce2823fd8b8c",
      "tree": "e46ed3e84545ec33f99f58f4b7211121bbfe3755",
      "parents": [
        "7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a"
      ],
      "author": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Mon Nov 02 13:52:27 2009 -0800"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 04:11:17 2009 +0100"
      },
      "message": "rcu: Prepare for synchronization fixes: clean up for non-NO_HZ handling of -\u003ecompleted counter\n\nImpose a clear locking design on non-NO_HZ handling of the\n-\u003ecompleted counter.  This increases the distance between the\nRCU and the CPU-hotplug mechanisms.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: \u003cstable@kernel.org\u003e # .32.x\nLKML-Reference: \u003c12571987491353-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    },
    {
      "commit": "7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a",
      "tree": "197950369a773afdf04af9bdfc4a2ce1d2b5d3af",
      "parents": [
        "c5e0cb3ddc5f14cedcfc50c0fb3b5fc6b56576da",
        "83f5b01ffbbaea6f97c9a79d21e240dbfb69f2f1"
      ],
      "author": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 04:10:31 2009 +0100"
      },
      "committer": {
        "name": "Ingo Molnar",
        "email": "mingo@elte.hu",
        "time": "Tue Nov 10 04:10:35 2009 +0100"
      },
      "message": "Merge branch \u0027core/urgent\u0027 into core/rcu\n\nMerge reason: Pick up RCU fixlet to base further commits on.\n\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n"
    }
  ],
  "next": "83f5b01ffbbaea6f97c9a79d21e240dbfb69f2f1"
}