From: Bodo Eggert <7eggert@gmx.de>
To: Jerry Jiang <wjiang@resilience.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Chris Snook <csnook@redhat.com>,
akpm@linux-foundation.org, ak@suse.de, heiko.carstens@de.ibm.com,
Subject: Re: [PATCH] make atomic_t volatile on all architectures
Date: Thu, 09 Aug 2007 11:10:16 +0200 [thread overview]
Message-ID: <E1IJ424-0000d7-HK@be1.lrz> (raw)
In-Reply-To: 8Q8rD-hh-7@gated-at.bofh.it
Jerry Jiang <wjiang@resilience.com> wrote:
> On Wed, 8 Aug 2007 21:18:25 -0700 (PDT)
>> On Wed, 8 Aug 2007, Chris Snook wrote:
>> > Some architectures currently do not declare the contents of an atomic_t to
>> > be
>> > volatile. This causes confusion since atomic_read() might not actually
>> > read anything if an optimizing compiler re-uses a value stored in a
>> > register, which can break code that loops until something external changes
>> > the value of an atomic_t.
>>
>> I'd be *much* happier with "atomic_read()" doing the "volatile" instead.
>>
>> The fact is, volatile on data structures is a bug. It's a wart in the C
>> language. It shouldn't be used.
>
> Why? It's a wart! Is it due to unclear C standard on volatile related point?
>
> Why the *volatile-accesses-in-code* is acceptable, does C standard make it
> clear?
http://lwn.net/Articles/233482/
--
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next parent reply other threads:[~2007-08-09 9:10 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8Q2Pg-8uV-23@gated-at.bofh.it>
[not found] ` <8Q7Fa-7rJ-1@gated-at.bofh.it>
[not found] ` <8Q8rD-hh-7@gated-at.bofh.it>
2007-08-09 9:10 ` Bodo Eggert [this message]
2007-08-09 9:18 ` [PATCH] make atomic_t volatile on all architectures Jerry Jiang
2007-08-09 15:00 ` Linus Torvalds
2007-08-08 23:07 Chris Snook
2007-08-08 23:18 ` Jesper Juhl
2007-08-08 23:31 ` Chris Snook
2007-08-08 23:51 ` Jesper Juhl
2007-08-08 23:25 ` Lennert Buytenhek
2007-08-08 23:35 ` Chris Snook
2007-08-09 1:03 ` Herbert Xu
2007-08-09 1:48 ` David Miller
2007-08-09 3:47 ` Paul E. McKenney
2007-08-09 7:47 ` Chris Snook
2007-08-09 8:30 ` Herbert Xu
2007-08-09 11:44 ` Chris Snook
2007-08-09 4:18 ` Linus Torvalds
2007-08-09 4:59 ` Jerry Jiang
2007-08-09 7:31 ` Chris Snook
2007-08-09 8:14 ` Heiko Carstens
2007-08-09 17:36 ` Chuck Ebbert
2007-08-09 17:55 ` Linus Torvalds
2007-08-09 18:20 ` Martin Schwidefsky
2007-08-12 5:53 ` Segher Boessenkool
2007-08-12 6:09 ` Linus Torvalds
2007-08-12 9:48 ` Martin Schwidefsky
2007-08-12 9:54 ` Linus Torvalds
2007-08-12 16:30 ` Segher Boessenkool
2007-08-12 18:11 ` Linus Torvalds
2007-08-12 19:13 ` Segher Boessenkool
2007-08-12 10:27 ` Segher Boessenkool
2007-08-12 17:59 ` Linus Torvalds
2007-08-12 9:47 ` Martin Schwidefsky
2007-08-12 10:35 ` Segher Boessenkool
2007-08-09 17:57 ` Martin Schwidefsky
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