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authorOleg Nesterov <oleg@redhat.com>2010-03-15 09:10:14 (GMT)
committerIngo Molnar <mingo@elte.hu>2010-04-02 18:12:02 (GMT)
commitc1804d547dc098363443667609c272d1e4d15ee8 (patch)
treec05ecb82cfb14b550c8d2242f5b0d4ad7e87bc52 /kernel/sched.c
parent1445c08d06c5594895b4fae952ef8a457e89c390 (diff)
downloadlinux-c1804d547dc098363443667609c272d1e4d15ee8.tar.xz
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>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 27774b5..f475c60 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5456,7 +5456,7 @@ 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);
@@ -5464,14 +5464,13 @@ 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;
}
/*