From f833bab87fca5c3ce13778421b1365845843b976 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Mon, 17 Aug 2009 14:34:59 -0700 Subject: 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 Signed-off-by: Venkatesh Pallipadi Cc: "Pallipadi Venkatesh" Cc: "Brown Len" LKML-Reference: <1250544899.2709.210.camel@sbs-t61.sc.intel.com> Signed-off-by: Thomas Gleixner --- drivers/acpi/processor_idle.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'drivers/acpi/processor_idle.c') 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, 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); } -- cgit v1.2.3