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From: "Chris Friesen" <cfriesen@nortel.com>
To: Andrew Haley <aph@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
	davids@webmaster.com, "Torvalds,
	Linus" <torvalds@linux-foundation.org>,
	"Kleen, Andi" <ak@suse.de>,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>
Subject: Re: Is gcc thread-unsafe?
Date: Fri, 26 Oct 2007 11:39:40 -0600	[thread overview]
Message-ID: <4722265C.7050907@nortel.com> (raw)
In-Reply-To: <18209.54926.290448.957962@zebedee.pink>

Andrew Haley wrote:

> We're listening, really.  It's unacceptable that gcc should break
> code.

In that case a conversion of a conditional branch to an unconditional 
write to a visible variable is not an acceptable behaviour.  Aside from 
the kernel issues, it would break any number of threaded userspace apps.

As was mentioned elsewhere, it's akin to sprinkling

int j = i; i = j;

throughout the code.  If "i" is accessed by multiple threads, this is 
not allowed unless a lock is held.

Chris

  reply	other threads:[~2007-10-26 17:55 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-25  3:24 Is gcc thread-unsafe? Nick Piggin
2007-10-25  3:46 ` Arjan van de Ven
2007-10-25  3:58   ` Nick Piggin
2007-10-25  4:29     ` David Schwartz
2007-10-25  4:35       ` Arjan van de Ven
2007-10-25 18:45         ` Måns Rullgård
2007-10-25  4:47       ` Nick Piggin
2007-10-25  9:40         ` Samuel Tardieu
2007-10-25  9:44         ` Samuel Tardieu
2007-10-25  9:54           ` Samuel Tardieu
2007-10-25  9:55           ` Andi Kleen
2007-10-25  7:15 ` Andi Kleen
2007-10-25 11:58   ` linux-os (Dick Johnson)
2007-10-25 12:16     ` Andi Kleen
2007-10-25 22:49   ` Nick Piggin
2007-10-25 23:09     ` Andi Kleen
2007-10-25 23:14       ` Linus Torvalds
2007-10-25 23:16         ` Andi Kleen
2007-10-25 23:32           ` Linus Torvalds
2007-10-25 23:42             ` Andi Kleen
2007-10-25 23:57               ` Linus Torvalds
2007-10-26  1:15                 ` Zachary Amsden
2007-10-26  4:57               ` Willy Tarreau
2007-10-25 23:43       ` Nick Piggin
2007-10-25 23:55         ` Andi Kleen
2007-10-25 23:57           ` Nick Piggin
2007-10-25 14:55 ` Linus Torvalds
2007-10-25 15:12   ` Pekka Enberg
2007-10-25 21:42   ` David Schwartz
2007-10-25 23:22     ` Nick Piggin
2007-10-26 11:59       ` Andrew Haley
2007-10-26 17:39         ` Chris Friesen [this message]
2007-10-26 11:59       ` Andrew Haley
2007-10-25 22:26   ` Ismail Dönmez
2007-10-25 22:56     ` Jeff Garzik
2007-10-25 23:04       ` Jeff Garzik
2007-10-31 22:10 ` Phillip Susi
     [not found] <fa.JbRGo0cQWncrcfKHmiNdvchsA50@ifi.uio.no>
     [not found] ` <fa.8qDECVaPIo7DWbjhQbyw6N5Infg@ifi.uio.no>
     [not found]   ` <fa.M4DOMggyrQmdTqekWSuw4xCxiTc@ifi.uio.no>
2007-10-25 23:27     ` Robert Hancock
     [not found] <e2e108260710260729x4603211cgb68d7434ce1e54e9@mail.gmail.com>
2007-10-26 14:40 ` Bart Van Assche
2007-10-26 15:09   ` Linus Torvalds
2007-10-26 15:34     ` Andrew Haley
2007-10-26 18:06       ` David Schwartz
2007-10-30 10:20         ` Andrew Haley
2007-11-02 15:29           ` Bart Van Assche
2007-11-02 15:38             ` Andrew Haley
2007-11-04 15:13               ` Bart Van Assche
2007-11-04 17:45                 ` Linus Torvalds
2007-11-04 17:58                   ` Andrew Haley
2007-11-04 18:06                   ` Bart Van Assche
2007-11-02 17:18             ` David Schwartz
2007-10-26 21:45     ` Giacomo Catenazzi
2007-10-26 22:24       ` Linus Torvalds
2007-10-26 15:27   ` Linus Torvalds
2007-10-26 16:28     ` Linus Torvalds
2007-10-26 17:07       ` Bart Van Assche
2007-10-26 17:12         ` Andrew Haley
2007-10-26 17:25           ` Linus Torvalds
2007-10-26 18:08         ` Alan Cox
2007-10-26 18:14           ` Linus Torvalds
2007-10-26 20:39           ` Andi Kleen
  -- strict thread matches above, loose matches on Subject: below --
2007-10-28 18:19 linux

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