From: Oleg Nesterov <oleg@tv-sign.ru>
To: Frank Mayhar <fmayhar@google.com>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org, Roland McGrath <roland@redhat.com>,
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 20:32:05 +0400 [thread overview]
Message-ID: <20080910163205.GA478@tv-sign.ru> (raw)
In-Reply-To: <1220992172.23059.20.camel@bobble.smo.corp.google.com>
On 09/09, Frank Mayhar wrote:
>
> On Tue, 2008-09-09 at 20:01 +0400, Oleg Nesterov wrote:
> > The patch has a lot of
> >
> > rcu_read_lock();
> > sig = rcu_dereference(tsk->signal);
> >
> > This is bogus, task_struct->signal is not protected by RCU.
>
> I just want to snapshot the field
> atomically. I guess I can just do an atomic read...
Missed this part...
No, no, you don't need an atomic read. Just do
sig = tsk->signal;
if (sig)
use(sig);
->signal must be stable, or the code is buggy anyway. (and the task
never changes its ->signal, it becomes NULL when the task dies).
BTW, thanks for doing this!
Oleg.
next prev parent reply other threads:[~2008-09-10 16:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-08 20:44 [PATCH 2.6.27-rc5] Fix itimer/many thread hang 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 [this message]
2008-09-10 4:04 ` Roland McGrath
2008-09-10 11:44 ` Oleg Nesterov
2008-09-10 3:59 ` Roland McGrath
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