[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>

parent 018a2212

kernel/sched.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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;
		}