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sched: Fix kthread_bind() by moving the body of kthread_bind() to sched.c

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Eric Paris reported that commit
f685ceacab causes boot time
PREEMPT_DEBUG complaints.

 [    4.590699] BUG: using smp_processor_id() in preemptible [00000000] code: rmmod/1314
 [    4.593043] caller is task_hot+0x86/0xd0

Since kthread_bind() messes with scheduler internals, move the
body to sched.c, and lock the runqueue.

Reported-by: Eric Paris <[email protected]>
Signed-off-by: Mike Galbraith <[email protected]>
Tested-by: Eric Paris <[email protected]>
Cc: Peter Zijlstra <[email protected]>
LKML-Reference: <[email protected]>
[ v2: fix !SMP build and clean up ]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Mike Galbraith 2009-10-29 11:48:30 +01:00 • committed by Ingo Molnar
commit b84ff7d6f1
2 changed files with 32 additions and 23 deletions
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32
kernel/sched.c
View file

@ -1996,6 +1996,38 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
p->sched_class->prio_changed(rq, p, oldprio, running);
}
/**
* kthread_bind - bind a just-created kthread to a cpu.
* @k: thread created by kthread_create().
* @cpu: cpu (might not be online, must be possible) for @k to run on.
*
* Description: This function is equivalent to set_cpus_allowed(),
* except that @cpu doesn't need to be online, and the thread must be
* stopped (i.e., just returned from kthread_create()).
*
* Function lives here instead of kthread.c because it messes with
* scheduler internals which require locking.
*/
void kthread_bind(struct task_struct *p, unsigned int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
/* Must have done schedule() in kthread() before we set_task_cpu */
if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
WARN_ON(1);
return;
}
spin_lock_irqsave(&rq->lock, flags);
set_task_cpu(p, cpu);
p->cpus_allowed = cpumask_of_cpu(cpu);
p->rt.nr_cpus_allowed = 1;
p->flags |= PF_THREAD_BOUND;
spin_unlock_irqrestore(&rq->lock, flags);
}
EXPORT_SYMBOL(kthread_bind);
#ifdef CONFIG_SMP
/*
* Is this task likely cache-hot: