提交 800d4d30 编写于 作者: Y Yong Zhang 提交者: Ingo Molnar

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: NYong Zhang <yong.zhang0@gmail.com>
Signed-off-by: NPeter 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: NIngo Molnar <mingo@elte.hu>
上级 1747b21f
......@@ -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);
}
......
#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;
......
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