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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 /drivers
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 'drivers')
-rw-r--r--drivers/acpi/processor_idle.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 0efa59e7e3af..66393d5c4c7c 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -162,8 +162,9 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
162 pr->power.timer_broadcast_on_state = state; 162 pr->power.timer_broadcast_on_state = state;
163} 163}
164 164
165static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) 165static void lapic_timer_propagate_broadcast(void *arg)
166{ 166{
167 struct acpi_processor *pr = (struct acpi_processor *) arg;
167 unsigned long reason; 168 unsigned long reason;
168 169
169 reason = pr->power.timer_broadcast_on_state < INT_MAX ? 170 reason = pr->power.timer_broadcast_on_state < INT_MAX ?
@@ -635,7 +636,8 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
635 working++; 636 working++;
636 } 637 }
637 638
638 lapic_timer_propagate_broadcast(pr); 639 smp_call_function_single(pr->id, lapic_timer_propagate_broadcast,
640 pr, 1);
639 641
640 return (working); 642 return (working);
641} 643}