From: Oleg Nesterov <oleg@tv-sign.ru>
To: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>, Frank Mayhar <fmayhar@google.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 2.6.27-rc5] Fix itimer/many thread hang.
Date: Wed, 10 Sep 2008 15:44:01 +0400 [thread overview]
Message-ID: <20080910114401.GA220@tv-sign.ru> (raw)
In-Reply-To: <20080910040404.245301541FE@magilla.localdomain>
On 09/09, Roland McGrath wrote:
>
> > As for this particular function, it seems to me that ->signal == NULL
> > is not possible, no?
>
> The concern is to make sure that the timer tick path is always safe for a
> tick that hits during release_task(current) in exit_notify(). A timer tick
> there can come with current->signal == NULL. We just need to make sure one
> way or another that this is safe.
run_posix_cpu_timers() must check ->signal != NULL anyway. (The same for
other functions like account_group_user_time() which are called by the
timer tick).
Apart from the timer tick, "current" should not use this function after
exit_notify().
And, if tsk != current, ->signal must be pinned, this means it can't be NULL.
Perhaps I missed something, but imho this check is confusing and misleading.
However, this is just a minor detail even if I am right.
Oleg.
next prev parent reply other threads:[~2008-09-10 11:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-08 20:44 Frank Mayhar
2008-09-09 7:03 ` Ingo Molnar
2008-09-09 16:01 ` Oleg Nesterov
2008-09-09 16:13 ` Oleg Nesterov
2008-09-09 20:29 ` Frank Mayhar
2008-09-10 12:12 ` Oleg Nesterov
2008-09-10 17:50 ` Frank Mayhar
2008-09-10 16:32 ` Oleg Nesterov
2008-09-10 4:04 ` Roland McGrath
2008-09-10 11:44 ` Oleg Nesterov [this message]
2008-09-10 3:59 ` Roland McGrath
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