From: george anzinger <george@mvista.com>
To: kuznet@ms2.inr.ac.ru
Cc: davem@redhat.com, niv@us.ibm.com, ak@suse.de, netdev@oss.sgi.com,
linux-net@vger.kernel.org, ak@muc.de, pekkas@netcore.fi
Subject: Re: System crash in tcp_fragment()
Date: Tue, 21 May 2002 08:42:51 -0700 [thread overview]
Message-ID: <acdq3b$5m6$2@main.gmane.org> (raw)
In-Reply-To: 200205211247.QAA05603@sex.inr.ac.ru
kuznet@ms2.inr.ac.ru wrote:
>
> Hello!
>
> > I understand the issue.
>
> I do not.
>
> +#define preempt_disable() \
> +do { \
> + ++current->preempt_count; \
> + barrier(); \
> +} while (0)
>
> Why does this work?
>
> Alexey
Preemption can only happen if the task is interrupted. The
interrupt exit code will not preempt if preempt_count is
more than zero. The barrier() forces the result to memory
so the interrupt code can find it.
--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
next prev parent reply other threads:[~2002-05-21 15:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.33.0205201836160.9301-100000@w-nivedita2.des.beaverton.ibm.com>
[not found] ` <3CE9E466.AC2358EE@mvista.com>
2002-05-21 6:00 ` System crash in tcp_fragment() David S. Miller
[not found] ` <20020520.230021.29510217.davem@redhat.com>
2002-05-21 7:25 ` george anzinger
2002-05-21 9:49 ` Andi Kleen
[not found] ` <3CE9F679.90ACF597@mvista.com>
2002-05-21 7:22 ` David S. Miller
2002-05-21 12:47 ` kuznet
2002-05-21 15:42 ` george anzinger [this message]
2002-05-21 12:54 ` Andi Kleen
2002-05-21 6:08 ` george anzinger
[not found] <20020520.173416.105610032.davem@redhat.com>
2002-05-21 1:00 ` kuznet
2002-05-21 1:49 ` Nivedita Singhvi
[not found] <3CE9960D.15D41380@mvista.com>
[not found] ` <200205210041.EAA04407@sex.inr.ac.ru>
2002-05-21 0:34 ` David S. Miller
2002-05-21 0:41 ` kuznet
[not found] <20020521015407.A1296@wotan.suse.de>
2002-05-21 0:11 ` kuznet
2002-05-21 0:20 ` Andi Kleen
2002-05-21 0:26 ` george anzinger
[not found] ` <20020521022007.A6248@wotan.suse.de>
2002-05-21 0:34 ` george anzinger
[not found] ` <3CE99434.20E7479C@mvista.com>
2002-05-21 0:18 ` David S. Miller
2002-05-21 0:39 ` Andi Kleen
[not found] <3CE95190.75C52E2D@mvista.com>
2002-05-20 20:29 ` Andi Kleen
[not found] ` <20020520222937.A1467@averell>
2002-05-20 21:18 ` george anzinger
2002-05-20 21:25 ` kuznet
2002-05-20 22:08 ` David S. Miller
[not found] ` <200205202125.BAA03545@sex.inr.ac.ru>
2002-05-20 23:01 ` george anzinger
2002-05-20 23:54 ` Andi Kleen
2002-05-20 19:42 george anzinger
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