Re: [PATCH 1/3] fix the racy usage of ->signal in account_group_xxx/run_posix_cpu_timers

Ingo Molnar
2008-11-17T15:50:46Z

* Oleg Nesterov <oleg@redhat.com> wrote:

> Another stupid patch for 2.6.28 until we find the good fix.
>
> Contrary to ad474caca3e2a0550b7ce0706527ad5ab389a4d4 changelog,
> other acct_group_xxx() helpers can be called after exit_notify() by
> timer tick. Thanks to Roland for pointing out this. Somehow I missed
> this simple fact when I read the original patch, and I am afraid I
> confused Frank during the discussion. Sorry.
>
> Fortunately, these helpers work with current, we can check
> ->exit_state to ensure that ->signal can't go away under us.
>
> Also, add the comment and compiler barrier to
> account_group_exec_runtime(), to make sure we load ->signal only
> once.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

applied to tip/sched/urgent, thanks Oleg.

Ingo