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authorOleg Nesterov <oleg@redhat.com>2009-06-17 16:27:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:54 -0700
commit371cbb387e33651b4c1326457116568ff01ac422 (patch)
tree4678d02d44fc9764f316e5d84e5d307cc14a0923 /kernel
parent63706172f332fd3f6e7458ebfb35fa6de9c21dc5 (diff)
downloadlinux-2.6.34-ux500-371cbb387e33651b4c1326457116568ff01ac422.tar.gz
kthreads: simplify migration_thread() exit path
Now that kthread_stop() can be used even if the task has already exited, we can kill the "wait_to_die:" loop in migration_thread(). But we must pin rq->migration_thread after creation. Actually, I don't think CPU_UP_CANCELED or CPU_DEAD should wait for ->migration_thread exit. Perhaps we can simplify this code a bit more. migration_call() can set ->should_stop and forget about this thread. But we need a new helper in kthred.c for that. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Vitaliy Gusev <vgusev@openvz.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c14
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 8fb88a906aa..247fd0fedd0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7045,7 +7045,7 @@ static int migration_thread(void *data)
if (cpu_is_offline(cpu)) {
spin_unlock_irq(&rq->lock);
- goto wait_to_die;
+ break;
}
if (rq->active_balance) {
@@ -7071,16 +7071,7 @@ static int migration_thread(void *data)
complete(&req->done);
}
__set_current_state(TASK_RUNNING);
- return 0;
-wait_to_die:
- /* Wait for kthread_stop */
- set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop()) {
- schedule();
- set_current_state(TASK_INTERRUPTIBLE);
- }
- __set_current_state(TASK_RUNNING);
return 0;
}
@@ -7494,6 +7485,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
rq = task_rq_lock(p, &flags);
__setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
task_rq_unlock(rq, &flags);
+ get_task_struct(p);
cpu_rq(cpu)->migration_thread = p;
break;
@@ -7524,6 +7516,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
kthread_bind(cpu_rq(cpu)->migration_thread,
cpumask_any(cpu_online_mask));
kthread_stop(cpu_rq(cpu)->migration_thread);
+ put_task_struct(cpu_rq(cpu)->migration_thread);
cpu_rq(cpu)->migration_thread = NULL;
break;
@@ -7533,6 +7526,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
migrate_live_tasks(cpu);
rq = cpu_rq(cpu);
kthread_stop(rq->migration_thread);
+ put_task_struct(rq->migration_thread);
rq->migration_thread = NULL;
/* Idle task back to normal (off runqueue, low prio) */
spin_lock_irq(&rq->lock);