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authorSuresh Siddha <suresh.b.siddha@intel.com>2009-08-17 17:34:59 -0400
committerThomas Gleixner <tglx@linutronix.de>2009-08-19 12:15:10 -0400
commitf833bab87fca5c3ce13778421b1365845843b976 (patch)
tree020c3e6a70dba34544c963c34647b605035be8fb /arch/x86/kernel/process.c
parentde809347aeef0a68c04576c464414d0e4dce59fc (diff)
clockevent: Prevent dead lock on clockevents_lock
Currently clockevents_notify() is called with interrupts enabled at some places and interrupts disabled at some other places. This results in a deadlock in this scenario. cpu A holds clockevents_lock in clockevents_notify() with irqs enabled cpu B waits for clockevents_lock in clockevents_notify() with irqs disabled cpu C doing set_mtrr() which will try to rendezvous of all the cpus. This will result in C and A come to the rendezvous point and waiting for B. B is stuck forever waiting for the spinlock and thus not reaching the rendezvous point. Fix the clockevents code so that clockevents_lock is taken with interrupts disabled and thus avoid the above deadlock. Also call lapic_timer_propagate_broadcast() on the destination cpu so that we avoid calling smp_call_function() in the clockevents notifier chain. This issue left us wondering if we need to change the MTRR rendezvous logic to use stop machine logic (instead of smp_call_function) or add a check in spinlock debug code to see if there are other spinlocks which gets taken under both interrupts enabled/disabled conditions. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com> Cc: "Brown Len" <len.brown@intel.com> LKML-Reference: <1250544899.2709.210.camel@sbs-t61.sc.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/process.c')
-rw-r--r--arch/x86/kernel/process.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 994dd6a4a2a0..071166a4ba83 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -519,16 +519,12 @@ static void c1e_idle(void)
519 if (!cpumask_test_cpu(cpu, c1e_mask)) { 519 if (!cpumask_test_cpu(cpu, c1e_mask)) {
520 cpumask_set_cpu(cpu, c1e_mask); 520 cpumask_set_cpu(cpu, c1e_mask);
521 /* 521 /*
522 * Force broadcast so ACPI can not interfere. Needs 522 * Force broadcast so ACPI can not interfere.
523 * to run with interrupts enabled as it uses
524 * smp_function_call.
525 */ 523 */
526 local_irq_enable();
527 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE, 524 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
528 &cpu); 525 &cpu);
529 printk(KERN_INFO "Switch to broadcast mode on CPU%d\n", 526 printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
530 cpu); 527 cpu);
531 local_irq_disable();
532 } 528 }
533 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); 529 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
534 530