From: TeJun Huh <tejun@aratech.co.kr>
To: linux-kernel@vger.kernel.org
Subject: Re: Race condition in 2.4 tasklet handling (cli() broken?)
Date: Sat, 23 Aug 2003 14:26:34 +0900 [thread overview]
Message-ID: <20030823052633.GA4307@atj.dyndns.org> (raw)
In-Reply-To: <20030823040931.GA3872@atj.dyndns.org>
Oops, Sorry. Only bh handling is relevant. Softirq and tasklet are
not of concern to cli().
On Sat, Aug 23, 2003 at 01:09:31PM +0900, TeJun Huh wrote:
> Additional suspicious things.
>
> 1. tasklet_kill() has similar race condition. mb() required before
> tasklet_unlock_wait().
Corrected 2.
global_bh_lock test inside wait_on_irq() suggests that cli() tries to
block not only interrupt handling but also bh handlings of all cpus;
however, current implementation does not guarantee that.
Because global_bh_lock is acquired in bh_action() <call trace:
handle_IRQ_event()->do_softirq()->tasklet_action()->bh_action()> after
decrementing local_irq_count(), other cpus may happily begin bh
handling while a cpu is still inside cli() - sti() critical section.
If bh hanlding is not guaranteed to be blocked during cli() - sti()
critical section, global_bh_lock test inside wait_on_irq() is
redundant and if it should be guaranteed, current implmentation seems
broken.
--
tejun
next prev parent reply other threads:[~2003-08-23 5:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-23 2:54 Race condition in 2.4 tasklet handling TeJun Huh
2003-08-23 4:09 ` Race condition in 2.4 tasklet handling (cli() broken?) TeJun Huh
2003-08-23 5:26 ` TeJun Huh [this message]
2003-08-23 10:28 ` Stephan von Krawczynski
2003-08-23 15:13 ` TeJun Huh
2003-08-23 15:37 ` Stephan von Krawczynski
2003-08-25 6:31 ` TeJun Huh
2003-08-25 7:23 ` Stephan von Krawczynski
2003-08-26 0:27 ` TeJun Huh
2003-08-23 15:56 ` Stephan von Krawczynski
2003-08-23 16:36 ` TeJun Huh
2003-08-24 3:27 ` TeJun Huh
2003-08-23 15:04 ` Race condition in 2.4 tasklet handling Anton Blanchard
[not found] <nKwX.1yy.17@gated-at.bofh.it>
2003-08-25 8:06 ` Race condition in 2.4 tasklet handling (cli() broken?) Peter T. Breuer
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