)]}'
{
  "commit": "90b421b52720b30644e104da002505f08a77c07a",
  "tree": "6e267789da89c5601db4ad1f376b549215f7afdc",
  "parents": [
    "bf09db97205d46b3e083582eb2799aedddd9953b"
  ],
  "author": {
    "name": "Thomas Gleixner",
    "email": "tglx@linutronix.de",
    "time": "Thu May 22 03:25:39 2014 +0000"
  },
  "committer": {
    "name": "Greg Kroah-Hartman",
    "email": "gregkh@linuxfoundation.org",
    "time": "Thu Jul 17 15:39:50 2014 -0700"
  },
  "message": "rtmutex: Fix deadlock detector for real\n\ncommit 397335f004f41e5fcf7a795e94eb3ab83411a17c upstream.\n\nThe current deadlock detection logic does not work reliably due to the\nfollowing early exit path:\n\n\t/*\n\t * Drop out, when the task has no waiters. Note,\n\t * top_waiter can be NULL, when we are in the deboosting\n\t * mode!\n\t */\n\tif (top_waiter \u0026\u0026 (!task_has_pi_waiters(task) ||\n\t\t\t   top_waiter !\u003d task_top_pi_waiter(task)))\n\t\tgoto out_unlock_pi;\n\nSo this not only exits when the task has no waiters, it also exits\nunconditionally when the current waiter is not the top priority waiter\nof the task.\n\nSo in a nested locking scenario, it might abort the lock chain walk\nand therefor miss a potential deadlock.\n\nSimple fix: Continue the chain walk, when deadlock detection is\nenabled.\n\nWe also avoid the whole enqueue, if we detect the deadlock right away\n(A-A). It\u0027s an optimization, but also prevents that another waiter who\ncomes in after the detection and before the task has undone the damage\nobserves the situation and detects the deadlock and returns\n-EDEADLOCK, which is wrong as the other task is not in a deadlock\nsituation.\n\nSigned-off-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nCc: Peter Zijlstra \u003cpeterz@infradead.org\u003e\nReviewed-by: Steven Rostedt \u003crostedt@goodmis.org\u003e\nCc: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nLink: http://lkml.kernel.org/r/20140522031949.725272460@linutronix.de\nSigned-off-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Mike Galbraith \u003cumgwanakikbuti@gmail.com\u003e\nSigned-off-by: Greg Kroah-Hartman \u003cgregkh@linuxfoundation.org\u003e\n\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "a242e691c993038f35ace870d245487d44b5bc16",
      "old_mode": 33188,
      "old_path": "kernel/rtmutex.c",
      "new_id": "8447256eb1bc2b2a3205c9cce793ec41d996efbb",
      "new_mode": 33188,
      "new_path": "kernel/rtmutex.c"
    }
  ]
}