From: Ralf Baechle <ralf@linux-mips.org>
To: Morten Larsen <mlarsen@broadcom.com>
Cc: linux-mips@linux-mips.org
Subject: Re: Bug in atomic_sub_if_positive
Date: Thu, 26 Jun 2008 14:11:20 +0200 [thread overview]
Message-ID: <20080626121120.GA5222@linux-mips.org> (raw)
In-Reply-To: <ADD7831BD377A74E9A1621D1EAAED18F0442AF00@NT-SJCA-0750.brcm.ad.broadcom.com>
On Wed, Jun 25, 2008 at 11:07:24PM -0700, Morten Larsen wrote:
> As far as I can tell the branch optimization fixes in 2.6.21 introduced
> a bug in atomic_sub_if_positive that causes it to return even when the
> sc instruction fails. The result is that e.g. down_trylock becomes
> unreliable as the semaphore counter is not always decremented.
I did play with a test program and can't reproduce the effect with my
assembler. I have darm memories of gas immitating some obscure behaviour
of the IRIX assembler and I think it doesn't do so for all MIPS targets.
So I'm wandering what toolchain have you been using?
Ralf
next prev parent reply other threads:[~2008-06-26 12:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-26 6:07 Bug in atomic_sub_if_positive Morten Larsen
2008-06-26 12:11 ` Ralf Baechle [this message]
2008-06-27 6:00 ` Morten Larsen
-- strict thread matches above, loose matches on Subject: below --
2008-07-02 0:12 Morten Larsen
2008-07-02 9:59 ` Thiemo Seufer
2008-07-02 10:31 ` Atsushi Nemoto
2008-07-02 10:51 ` Thiemo Seufer
2008-07-03 15:04 ` Atsushi Nemoto
2008-07-04 11:54 ` Ralf Baechle
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