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Commit 5cbd54ef authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: fix init_idle()'s use of sched_clock() 



Maciej Rutecki reported:

> I have this bug during suspend to disk:
>
> [  188.592151] Enabling non-boot CPUs ...
> [  188.592151] SMP alternatives: switching to SMP code
> [  188.666058] BUG: using smp_processor_id() in preemptible
> [00000000]
> code: suspend_to_disk/2934
> [  188.666064] caller is native_sched_clock+0x2b/0x80

Which, as noted by Linus, was caused by me, via:

  7cbaef9c "sched: optimize sched_clock() a bit"

Move the rq locking a bit earlier in the initialization sequence,
that will make the sched_clock() call in init_idle() non-preemptible.

Reported-by: default avatarMaciej Rutecki <maciej.rutecki@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a2d47777

kernel/sched.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -5870,6 +5870,8 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu) 
	struct rq *rq = cpu_rq(cpu);

	struct rq *rq = cpu_rq(cpu);

	unsigned long flags;

	unsigned long flags;





	spin_lock_irqsave(&rq->lock, flags);



	__sched_fork(idle);

	__sched_fork(idle);

	idle->se.exec_start = sched_clock();

	idle->se.exec_start = sched_clock();
@@ -5877,7 +5879,6 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu) 
	idle->cpus_allowed = cpumask_of_cpu(cpu);

	idle->cpus_allowed = cpumask_of_cpu(cpu);

	__set_task_cpu(idle, cpu);

	__set_task_cpu(idle, cpu);





	spin_lock_irqsave(&rq->lock, flags);

	rq->curr = rq->idle = idle;

	rq->curr = rq->idle = idle;

#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)

#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)

	idle->oncpu = 1;

	idle->oncpu = 1;