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| author | Yong Zhang <yong.zhang0@gmail.com> | 2011-02-20 15:08:14 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-02-23 11:33:59 +0100 |
| commit | 800d4d30c8f20bd728e5741a3b77c4859a613f7c (patch) | |
| tree | 1eb329fb8a1dce1c1432c07e19494a3e1fb68499 | |
| parent | 1747b21fecbfb63fbf6b9624e8b92707960d5a97 (diff) | |
| download | lwn-800d4d30c8f20bd728e5741a3b77c4859a613f7c.tar.gz lwn-800d4d30c8f20bd728e5741a3b77c4859a613f7c.zip | |
sched, autogroup: Stop going ahead if autogroup is disabled
when autogroup is disable from the beginning,
sched_autogroup_create_attach()
autogroup_move_group() <== 1
sched_move_task() <== 2
task_move_group_fair()
set_task_rq()
task_group()
autogroup_task_group()
We go the whole path without doing anything useful.
Then stop going further if autogroup is disabled.
But there will be a race window between 1 and 2, in which
sysctl_sched_autogroup_enabled is enabled. This issue
will be toke by following patch.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1298185696-4403-4-git-send-email-yong.zhang0@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/sched_autogroup.c | 4 | ||||
| -rw-r--r-- | kernel/sched_autogroup.h | 5 |
2 files changed, 9 insertions, 0 deletions
diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c index 9fb656283157..137a096ae9d8 100644 --- a/kernel/sched_autogroup.c +++ b/kernel/sched_autogroup.c @@ -161,11 +161,15 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag) p->signal->autogroup = autogroup_kref_get(ag); + if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled)) + goto out; + t = p; do { sched_move_task(t); } while_each_thread(p, t); +out: unlock_task_sighand(p, &flags); autogroup_kref_put(prev); } diff --git a/kernel/sched_autogroup.h b/kernel/sched_autogroup.h index 7b859ffe5dad..05577055cfca 100644 --- a/kernel/sched_autogroup.h +++ b/kernel/sched_autogroup.h @@ -1,6 +1,11 @@ #ifdef CONFIG_SCHED_AUTOGROUP struct autogroup { + /* + * reference doesn't mean how many thread attach to this + * autogroup now. It just stands for the number of task + * could use this autogroup. + */ struct kref kref; struct task_group *tg; struct rw_semaphore lock; |