From: Russell King <rmk@arm.linux.org.uk>
To: Jes Sorensen <jes@wildopensource.com>
Cc: linux-kernel@vger.kernel.org, alan@redhat.com,
Marcelo Tosatti <marcelo@conectiva.com.br>
Subject: Re: [patch 2.4] make tty->count atomic_t
Date: Fri, 4 Apr 2003 00:06:08 +0100 [thread overview]
Message-ID: <20030404000608.B18485@flint.arm.linux.org.uk> (raw)
In-Reply-To: <16012.27749.781757.8312@trained-monkey.org>; from jes@wildopensource.com on Thu, Apr 03, 2003 at 12:16:21PM -0500
On Thu, Apr 03, 2003 at 12:16:21PM -0500, Jes Sorensen wrote:
> I believe the 2.4 tty code is racey in the way it handles tty->count.
> release_dev() does the tty->count-- thing without protecting against
> parallel execution, hence tty->count can end up a random state as
> tty->count-- isn't guaranteed to be atomic (load-store architectures and
> architectures with weak memory ordering etc).
Isn't release_dev() only called under the BKL, which guarantees the
old "single-thread in the kernel at a time" behaviour from pre-SMP
Linux ?
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
next prev parent reply other threads:[~2003-04-03 22:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-03 17:16 [patch 2.4] make tty->count atomic_t Jes Sorensen
2003-04-03 23:06 ` Russell King [this message]
2003-04-03 23:18 ` Jes Sorensen
2003-04-03 23:28 ` Russell King
2003-04-04 0:13 ` Jes Sorensen
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