Re: + taskstats-add-all-thread-stats-for-taskstats_cmd_attr_tgid.patch added to -mm tree
- From: Oleg Nesterov <oleg@xxxxxxxxxx>
- Date: Mon, 17 Sep 2007 20:26:27 +0400
On 09/15, Guillaume Chazarain wrote:
Le Thu, 13 Sep 2007 16:41:41 +0400,
Oleg Nesterov <oleg@xxxxxxxxxx> a ??crit :
+ do
+ if (!tsk->exit_state)
+ add_tsk(stats, tsk);
+ while_each_thread(first, tsk);
This reminds me. The "!tsk->exit_state" is not good and racy, it
can't prevent the double accounting (of course, I don't blame this
patch).
I documented this in v4, but I was wondering if always setting
tsk->exit_state under the protection of lock_task_sighand() would fix
the race.
No, this is not enough. There is a window between do_exit()->taskstats_exit()
and do_exit()->exit_notify() which sets ->exit_state. Probably, we can
shift taskstats_exit() into exit_notify() but this is not good.
Oleg.
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- Re: + taskstats-add-all-thread-stats-for-taskstats_cmd_attr_tgid.patch added to -mm tree
- From: Guillaume Chazarain
- Re: + taskstats-add-all-thread-stats-for-taskstats_cmd_attr_tgid.patch added to -mm tree
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