[PATCH] sched: make cpu_clock() not use the rq clock

it is enough to disable interrupts to get the precise rq-clock
of the local CPU.

this also solves an NMI watchdog regression: the NMI watchdog
calls touch_softlockup_watchdog(), which might deadlock on
rq->lock if the NMI hits an rq-locked critical section.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 4 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index cc6c1192c448..3eed860cf292 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -383,13 +383,12 @@ static inline unsigned long long rq_clock(struct rq *rq)
  */
 unsigned long long cpu_clock(int cpu)
 {
-        struct rq *rq = cpu_rq(cpu);
         unsigned long long now;
         unsigned long flags;
 
-        spin_lock_irqsave(&rq->lock, flags);
-        now = rq_clock(rq);
-        spin_unlock_irqrestore(&rq->lock, flags);
+        local_irq_save(flags);
+        now = rq_clock(cpu_rq(cpu));
+        local_irq_restore(flags);
 
         return now;
 }