[IA64] perfmon: make pfm_sysctl a global, and other cleanup
- make pfm_sysctl a global such that it is possible
to enable/disable debug printk in sampling formats
using PFM_DEBUG.
- remove unused pfm_debug_var variable
- fix a bug in pfm_handle_work where an BUG_ON() could
be triggered. There is a path where pfm_handle_work()
can be called with interrupts enabled, i.e., when
TIF_NEED_RESCHED is set. The fix correct the masking
and unmasking of interrupts in pfm_handle_work() such
that we restore the interrupt mask as it was upon entry.
signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 71147be..376fcbc 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -480,14 +480,6 @@
#define PFM_CMD_ARG_MANY -1 /* cannot be zero */
typedef struct {
- int debug; /* turn on/off debugging via syslog */
- int debug_ovfl; /* turn on/off debug printk in overflow handler */
- int fastctxsw; /* turn on/off fast (unsecure) ctxsw */
- int expert_mode; /* turn on/off value checking */
- int debug_pfm_read;
-} pfm_sysctl_t;
-
-typedef struct {
unsigned long pfm_spurious_ovfl_intr_count; /* keep track of spurious ovfl interrupts */
unsigned long pfm_replay_ovfl_intr_count; /* keep track of replayed ovfl interrupts */
unsigned long pfm_ovfl_intr_count; /* keep track of ovfl interrupts */
@@ -514,8 +506,8 @@
static pmu_config_t *pmu_conf;
/* sysctl() controls */
-static pfm_sysctl_t pfm_sysctl;
-int pfm_debug_var;
+pfm_sysctl_t pfm_sysctl;
+EXPORT_SYMBOL(pfm_sysctl);
static ctl_table pfm_ctl_table[]={
{1, "debug", &pfm_sysctl.debug, sizeof(int), 0666, NULL, &proc_dointvec, NULL,},
@@ -1576,7 +1568,7 @@
goto abort_locked;
}
- DPRINT(("[%d] fd=%d type=%d\n", current->pid, msg->pfm_gen_msg.msg_ctx_fd, msg->pfm_gen_msg.msg_type));
+ DPRINT(("fd=%d type=%d\n", msg->pfm_gen_msg.msg_ctx_fd, msg->pfm_gen_msg.msg_type));
ret = -EFAULT;
if(copy_to_user(buf, msg, sizeof(pfm_msg_t)) == 0) ret = sizeof(pfm_msg_t);
@@ -3695,8 +3687,6 @@
pfm_sysctl.debug = m == 0 ? 0 : 1;
- pfm_debug_var = pfm_sysctl.debug;
-
printk(KERN_INFO "perfmon debugging %s (timing reset)\n", pfm_sysctl.debug ? "on" : "off");
if (m == 0) {
@@ -4996,13 +4986,21 @@
}
static int pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds);
-
+ /*
+ * pfm_handle_work() can be called with interrupts enabled
+ * (TIF_NEED_RESCHED) or disabled. The down_interruptible
+ * call may sleep, therefore we must re-enable interrupts
+ * to avoid deadlocks. It is safe to do so because this function
+ * is called ONLY when returning to user level (PUStk=1), in which case
+ * there is no risk of kernel stack overflow due to deep
+ * interrupt nesting.
+ */
void
pfm_handle_work(void)
{
pfm_context_t *ctx;
struct pt_regs *regs;
- unsigned long flags;
+ unsigned long flags, dummy_flags;
unsigned long ovfl_regs;
unsigned int reason;
int ret;
@@ -5039,18 +5037,15 @@
//if (CTX_OVFL_NOBLOCK(ctx)) goto skip_blocking;
if (reason == PFM_TRAP_REASON_RESET) goto skip_blocking;
+ /*
+ * restore interrupt mask to what it was on entry.
+ * Could be enabled/diasbled.
+ */
UNPROTECT_CTX(ctx, flags);
- /*
- * pfm_handle_work() is currently called with interrupts disabled.
- * The down_interruptible call may sleep, therefore we
- * must re-enable interrupts to avoid deadlocks. It is
- * safe to do so because this function is called ONLY
- * when returning to user level (PUStk=1), in which case
- * there is no risk of kernel stack overflow due to deep
- * interrupt nesting.
- */
- BUG_ON(flags & IA64_PSR_I);
+ /*
+ * force interrupt enable because of down_interruptible()
+ */
local_irq_enable();
DPRINT(("before block sleeping\n"));
@@ -5064,12 +5059,12 @@
DPRINT(("after block sleeping ret=%d\n", ret));
/*
- * disable interrupts to restore state we had upon entering
- * this function
+ * lock context and mask interrupts again
+ * We save flags into a dummy because we may have
+ * altered interrupts mask compared to entry in this
+ * function.
*/
- local_irq_disable();
-
- PROTECT_CTX(ctx, flags);
+ PROTECT_CTX(ctx, dummy_flags);
/*
* we need to read the ovfl_regs only after wake-up
@@ -5095,7 +5090,9 @@
ctx->ctx_ovfl_regs[0] = 0UL;
nothing_to_do:
-
+ /*
+ * restore flags as they were upon entry
+ */
UNPROTECT_CTX(ctx, flags);
}