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clockevent: Prevent dead lock on clockevents_lock

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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 <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Cc: "Pallipadi Venkatesh" <[email protected]>
Cc: "Brown Len" <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
This commit is contained in:
Suresh Siddha 2009-08-17 14:34:59 -07:00 • committed by Thomas Gleixner
commit f833bab87f
4 changed files with 18 additions and 17 deletions
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6
drivers/acpi/processor_idle.c
View file

@ -162,8 +162,9 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
pr->power.timer_broadcast_on_state = state;
}
static void lapic_timer_propagate_broadcast(struct acpi_processor *pr)
static void lapic_timer_propagate_broadcast(void *arg)
{
struct acpi_processor *pr = (struct acpi_processor *) arg;
unsigned long reason;
reason = pr->power.timer_broadcast_on_state < INT_MAX ?
@ -635,7 +636,8 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
working++;
}
lapic_timer_propagate_broadcast(pr);
smp_call_function_single(pr->id, lapic_timer_propagate_broadcast,
pr, 1);
return (working);
}