From: Andrea Arcangeli <andrea@suse.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>,
linas@austin.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: PATCH: Race in 2.6.0-test2 timer code
Date: Wed, 30 Jul 2003 10:28:48 +0200 [thread overview]
Message-ID: <20030730082848.GC23835@dualathlon.random> (raw)
In-Reply-To: <Pine.LNX.4.44.0307300932560.433-100000@localhost.localdomain>
On Wed, Jul 30, 2003 at 09:34:40AM +0200, Ingo Molnar wrote:
>
> On Wed, 30 Jul 2003, Andrea Arcangeli wrote:
>
> > The thing triggered simply by running setitimer in one function, while
> > the it_real_fn was running in the other cpu. I don't see how 2.6 can
> > have fixed this, it_real_fun can still trivially call add_timer while
> > you run inside do_setitimer in 2.6 too. [...]
>
> This is not a race that can happen. itimer does this:
>
> del_timer_sync();
> add_timer();
>
> how can the add_timer() still happen while it_real_fn is still running on
> another CPU?
it's not add_timer against add_timer in this case, it's del_timer_sync
against add_timer.
cpu0 cpu1
------------ --------------------
do_setitimer
it_real_fn
del_timer_sync add_timer -> crash
Andrea
next prev parent reply other threads:[~2003-07-30 8:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-29 15:41 PATCH: Race in 2.6.0-test2 timer code linas
2003-07-29 20:56 ` Andrew Morton
2003-07-30 5:57 ` Ingo Molnar
2003-07-30 6:36 ` Andrew Morton
2003-07-30 7:07 ` Ingo Molnar
2003-07-30 7:34 ` Andrea Arcangeli
2003-07-30 7:34 ` Ingo Molnar
2003-07-30 8:28 ` Andrea Arcangeli [this message]
2003-07-30 10:31 ` Ingo Molnar
2003-07-30 11:16 ` Andrea Arcangeli
2003-07-30 11:49 ` Ingo Molnar
2003-07-30 12:34 ` Andrea Arcangeli
2003-07-30 21:18 ` linas
2003-07-30 22:06 ` Andrea Arcangeli
2003-07-30 22:17 ` Andrea Arcangeli
2003-07-31 7:04 ` Ingo Molnar
2003-07-30 21:19 ` Andrea Arcangeli
2003-07-30 23:43 ` linas
2003-07-30 23:56 ` Andrea Arcangeli
2003-07-30 23:54 ` Andrew Morton
2003-07-31 0:16 ` Andrea Arcangeli
2003-07-31 17:23 ` linas
2003-08-01 6:27 ` Ingo Molnar
2003-07-30 7:40 ` Ingo Molnar
2003-07-30 8:37 ` Andrea Arcangeli
2003-07-30 10:34 ` Ingo Molnar
2003-07-30 10:51 ` Andrew Morton
2003-07-30 11:28 ` Andrea Arcangeli
2003-07-30 11:22 ` Andrea Arcangeli
2003-07-30 20:05 ` linas
2003-07-31 6:50 ` Ingo Molnar
2003-07-31 22:56 ` linas
2003-08-01 6:23 ` Ingo Molnar
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