From: Andi Kleen <andi@firstfloor.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
fbl@redhat.com, nhorman@redhat.com, davem@redhat.com,
oleg@redhat.com, eric.dumazet@gmail.com
Subject: Re: [PATCH] net: fix race in the receive/select
Date: Mon, 29 Jun 2009 11:12:33 +0200 [thread overview]
Message-ID: <87eit3l7y6.fsf@basil.nowhere.org> (raw)
In-Reply-To: <20090625122545.GA3625@jolsa.lab.eng.brq.redhat.com> (Jiri Olsa's message of "Thu, 25 Jun 2009 14:25:45 +0200")
Jiri Olsa <jolsa@redhat.com> writes:
> Adding memory barrier to the __pollwait function paired with
> receive callbacks. The smp_mb__after_lock define is added,
> since {read|write|spin}_lock() on x86 are full memory barriers.
I was wondering did you see that race actually happening in practice?
If yes on which system?
At least on x86 I can't see how it happens. mb() is only a compile
time barrier and the compiler doesn't optimize over indirect callbacks
like __pollwait() anyways.
It might be still needed on some weaker ordered architectures, but did you
actually see it there?
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-06-29 9:12 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-25 12:25 [PATCH] net: fix race in the receive/select Jiri Olsa
2009-06-25 12:24 ` Oleg Nesterov
2009-06-26 1:31 ` Davide Libenzi
2009-06-26 1:59 ` Eric Dumazet
2009-06-26 2:04 ` Davide Libenzi
2009-06-26 2:11 ` David Miller
2009-06-26 2:19 ` Eric Dumazet
2009-06-26 3:14 ` Davide Libenzi
2009-06-26 5:42 ` Jarek Poplawski
2009-06-26 8:10 ` Jarek Poplawski
2009-06-26 13:57 ` Oleg Nesterov
2009-06-26 17:32 ` Davide Libenzi
2009-06-26 14:50 ` Oleg Nesterov
2009-06-26 18:12 ` Davide Libenzi
2009-06-26 18:17 ` David Miller
2009-06-26 19:35 ` Eric Dumazet
2009-06-29 9:34 ` Jiri Olsa
2009-06-28 11:10 ` Jarek Poplawski
2009-06-28 11:22 ` Jarek Poplawski
2009-06-28 18:04 ` Oleg Nesterov
2009-06-28 21:48 ` Jarek Poplawski
2009-06-29 9:27 ` Jiri Olsa
2009-06-26 13:46 ` Oleg Nesterov
2009-06-25 23:18 ` Eric Dumazet
2009-06-26 1:50 ` Tejun Heo
2009-06-29 9:12 ` Andi Kleen [this message]
2009-06-29 9:24 ` Jiri Olsa
2009-06-29 16:59 ` Zan Lynx
2009-06-29 17:29 ` Andi Kleen
2009-07-01 3:39 ` Herbert Xu
2009-07-01 6:27 ` Andi Kleen
2009-07-01 7:03 ` Herbert Xu
2009-07-01 7:22 ` Andi Kleen
2009-07-01 8:31 ` Herbert Xu
2009-07-01 8:44 ` Jiri Olsa
2009-07-01 10:58 ` Herbert Xu
2009-07-01 13:07 ` Herbert Xu
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