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| author | Oleg Nesterov <oleg@redhat.com> | 2010-03-15 10:10:14 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-07-20 19:11:47 +0200 |
| commit | 2d5a7c7241f20ee8e90452a47b773cffbb4c2412 (patch) | |
| tree | aee6187237b78d1d4d3ef5ef5f02e4d2a2c30e63 | |
| parent | ae35e6fffd929f71b6ea1193862d50b56b636a1b (diff) | |
| download | lwn-2d5a7c7241f20ee8e90452a47b773cffbb4c2412.tar.gz lwn-2d5a7c7241f20ee8e90452a47b773cffbb4c2412.zip | |
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.
[ upstream commit: c1804d547dc098363443667609c272d1e4d15ee8 ]
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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | kernel/sched.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 59db39610b20..95ffa5399479 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7747,7 +7747,7 @@ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p) struct rq *rq = cpu_rq(dead_cpu); int needs_cpu, uninitialized_var(dest_cpu); unsigned long flags; -again: + local_irq_save(flags); raw_spin_lock(&rq->lock); @@ -7755,14 +7755,13 @@ again: if (needs_cpu) dest_cpu = select_fallback_rq(dead_cpu, p); raw_spin_unlock(&rq->lock); - - /* It can have affinity changed while we were choosing. */ + /* + * It can only fail if we race with set_cpus_allowed(), + * in the racer should migrate the task anyway. + */ if (needs_cpu) - needs_cpu = !__migrate_task(p, dead_cpu, dest_cpu); + __migrate_task(p, dead_cpu, dest_cpu); local_irq_restore(flags); - - if (unlikely(needs_cpu)) - goto again; } /* |