sched: move_task_off_dead_cpu(): Remove retry logic
The previous patch preserved the retry logic, but it looks unneeded. __migrate_task() can only fail if we raced with migration after we dropped the lock, but in this case the caller of set_cpus_allowed/etc must initiate migration itself if ->on_rq == T. We already fixed p->cpus_allowed, the changes in active/online masks must be visible to racer, it should migrate the task to online cpu correctly. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100315091014.GA9138@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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c1804d547d
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@ -5456,7 +5456,7 @@ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
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struct rq *rq = cpu_rq(dead_cpu);
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int needs_cpu, uninitialized_var(dest_cpu);
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unsigned long flags;
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again:
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local_irq_save(flags);
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raw_spin_lock(&rq->lock);
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@ -5464,14 +5464,13 @@ again:
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if (needs_cpu)
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dest_cpu = select_fallback_rq(dead_cpu, p);
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raw_spin_unlock(&rq->lock);
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/* It can have affinity changed while we were choosing. */
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/*
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* It can only fail if we race with set_cpus_allowed(),
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* in the racer should migrate the task anyway.
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*/
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if (needs_cpu)
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needs_cpu = !__migrate_task(p, dead_cpu, dest_cpu);
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__migrate_task(p, dead_cpu, dest_cpu);
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local_irq_restore(flags);
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if (unlikely(needs_cpu))
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goto again;
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}
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/*
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