clockevent: Prevent dead lock on clockevents_lock

This is a merge of two mainline commits, intended
for stable@kernel.org submission for 2.6.27 kernel.

commit f833bab87fca5c3ce13778421b1365845843b976
and

commit 918aae42aa9b611a3663b16ae849fdedc67c2292
Changelog of both:

    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>
    Cc: "Brown Len" <len.brown@intel.com>
    Cc: stable@kernel.org
    LKML-Reference: <1250544899.2709.210.camel@sbs-t61.sc.intel.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

    I got following warning on ia64 box:
      In function 'acpi_processor_power_verify':
      642: warning: passing argument 2 of 'smp_call_function_single' from
      incompatible pointer type

    This smp_call_function_single() was introduced by a commit
    f833bab87fca5c3ce13778421b1365845843b976:

    The problem is that the lapic_timer_propagate_broadcast() has 2 versions:
    One is real code that modified in the above commit, and the other is NOP
    code that used when !ARCH_APICTIMER_STOPS_ON_C3:

      static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }

    So I got warning because of !ARCH_APICTIMER_STOPS_ON_C3.

    We really want to do nothing here on !ARCH_APICTIMER_STOPS_ON_C3, so
    modify lapic_timer_propagate_broadcast() of real version to use
    smp_call_function_single() in it.

    Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
    Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
    Signed-off-by: Len Brown <len.brown@intel.com>

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5639e27cb497..94483a2a61f7 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -317,8 +317,9 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr,
 		pr->power.timer_broadcast_on_state = state;
 }
 
-static void acpi_propagate_timer_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 ?
@@ -327,6 +328,12 @@ static void acpi_propagate_timer_broadcast(struct acpi_processor *pr)
 	clockevents_notify(reason, &pr->id);
 }
 
+static void lapic_timer_propagate_broadcast(struct acpi_processor *pr)
+{
+	smp_call_function_single(pr->id, __lapic_timer_propagate_broadcast,
+				 (void *)pr, 1);
+}
+
 /* Power(C) State timer broadcast control */
 static void acpi_state_timer_broadcast(struct acpi_processor *pr,
 				       struct acpi_processor_cx *cx,
@@ -347,7 +354,7 @@ static void acpi_state_timer_broadcast(struct acpi_processor *pr,
 
 static void acpi_timer_check_state(int state, struct acpi_processor *pr,
 				   struct acpi_processor_cx *cstate) { }
-static void acpi_propagate_timer_broadcast(struct acpi_processor *pr) { }
+static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }
 static void acpi_state_timer_broadcast(struct acpi_processor *pr,
 				       struct acpi_processor_cx *cx,
 				       int broadcast)
@@ -1177,7 +1184,7 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
 			working++;
 	}
 
-	acpi_propagate_timer_broadcast(pr);
+	lapic_timer_propagate_broadcast(pr);
 
 	return (working);
 }