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From: James Bottomley <James.Bottomley@steeleye.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: tonyb@cybernetics.com, Marcelo Tosatti <marcelo@conectiva.com.br>,
	SCSI Mailing List <linux-scsi@vger.kernel.org>,
	dougg@torque.net
Subject: Re: [PATCH] 2.4.21 fix race condition in sg.c
Date: 27 Jun 2003 09:47:00 -0500	[thread overview]
Message-ID: <1056725222.2099.21.camel@mulgrave> (raw)
In-Reply-To: <1056724288.3172.43.camel@dhcp22.swansea.linux.org.uk>

On Fri, 2003-06-27 at 09:31, Alan Cox wrote:
> For cases you just have to force compiler ordering you can use barrier, which
> resolves to 
> 
>  __asm__ __volatile__("": : :"memory")
> 
> ie an empty space that affects memory so causes write backs 

Right.  The code in question is the only statement between an if block
and a function call, thus I believe it's safe from gcc reordering, so I
was assuming the intent was externally visible ordering (which can be
the expensive one).

James



  reply	other threads:[~2003-06-27 14:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-06-27 13:52 [PATCH] 2.4.21 fix race condition in sg.c Tony Battersby
2003-06-27 14:10 ` James Bottomley
2003-06-27 14:31   ` Alan Cox
2003-06-27 14:47     ` James Bottomley [this message]
2003-06-27 14:57   ` Tony Battersby
2003-06-27 15:00     ` Jeff Garzik
2003-06-27 15:11     ` James Bottomley
2003-06-27 15:38       ` Tony Battersby
  -- strict thread matches above, loose matches on Subject: below --
2003-06-26 15:18 Tony Battersby
2003-06-26 22:15 ` Douglas Gilbert

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