On 09/03, Tejun Heo wrote:
>
> Can you please wait a bit?
Sure. But just in case, I mean the simple patch below.
Feel free to incorporate into 4/4, or I can resend it later.
Oleg.
------------------------------------------------------------------------------
[PATCH] freezer: remove the pointless/unsafe __thaw_task()->recalc_sigpending_and_wake()
Remove __thaw_task()->recalc_sigpending_and_wake(). It was copied from
cancel_freezing() recently, but it was always wrong.
It is pointless, contary to the comment it can't clear TIF_SIGPENDING.
Not to mention, we must never do this with !current task, this is wrong.
The usage of ->sighand is not safe if the caller is cgroup_freezer, we
can racw with exit.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
kernel/freezer.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)
--- 3.1/kernel/freezer.c~kill_rspaw 2011-09-02 18:52:46.000000000 +0200
+++ 3.1/kernel/freezer.c 2011-09-02 19:03:30.000000000 +0200
@@ -150,18 +150,10 @@ void __thaw_task(struct task_struct *p)
* be visible to @p as waking up implies wmb. Waking up inside
* freezer_lock also prevents wakeups from leaking outside
* refrigerator.
- *
- * If !FROZEN, @p hasn't reached refrigerator, recalc sigpending to
- * avoid leaving dangling TIF_SIGPENDING behind.
*/
spin_lock_irqsave(&freezer_lock, flags);
- if (frozen(p)) {
+ if (frozen(p))
wake_up_process(p);
- } else {
- spin_lock(&p->sighand->siglock);
- recalc_sigpending_and_wake(p);
- spin_unlock(&p->sighand->siglock);
- }
spin_unlock_irqrestore(&freezer_lock, flags);
}
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