Messages in this thread Patch in this message | | | Date | Fri, 2 Sep 2011 19:30:39 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() |
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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@redhat.com> ---
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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