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From: Grant Grundler <grundler@parisc-linux.org>
To: Randolph Chung <tausq@debian.org>
Cc: parisc-linux@lists.parisc-linux.org
Subject: Re: [parisc-linux] some other small bitops.h suggestion?
Date: Wed, 13 Apr 2005 23:07:27 -0600	[thread overview]
Message-ID: <20050414050727.GA30838@colo.lackof.org> (raw)
In-Reply-To: <20050414013105.GB17749@tausq.org>

On Wed, Apr 13, 2005 at 06:31:05PM -0700, Randolph Chung wrote:
> One might argue that the contents pointed to by addr can be volatile,
> but in that case shouldn't it be "unsigned long * volatile addr"?

Originally it's to make sure gcc doesn't optimize the read/modify/write
completely away if it thinks no one is using the result.

> In this case, we are doing a single operation to *addr, and this
> function is explicitly not atomic, so I am not quite sure why we need
> volatile at all.

James Bottomley dug up the original thread:
	http://marc.theaimsgroup.com/?t=108826637900003

If __set_bit() doesn't need volatile, then is the same true
for __clear_bit and __change_bit?

grant
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  parent reply	other threads:[~2005-04-14  5:07 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-03 14:32 [parisc-linux] pthread problems - test program Randolph Chung
2005-04-03 19:07 ` John David Anglin
2005-04-03 20:24 ` John David Anglin
2005-04-04  0:53   ` Randolph Chung
2005-04-03 20:41 ` John David Anglin
2005-04-04  0:50   ` Randolph Chung
2005-04-05  0:00     ` Carlos O'Donell
2005-04-05  0:02     ` Carlos O'Donell
2005-04-05  6:00       ` Carlos O'Donell
2005-04-06 20:12         ` John David Anglin
2005-04-06 20:25           ` Carlos O'Donell
2005-04-06 20:52             ` John David Anglin
2005-04-06 20:28           ` Carlos O'Donell
2005-04-07  2:45           ` John David Anglin
2005-04-08  2:56             ` John David Anglin
2005-04-08 21:29               ` Carlos O'Donell
2005-04-08 22:54                 ` John David Anglin
     [not found]                   ` <20050409055852.GM1833@baldric.uwo.ca>
2005-04-09  6:37                     ` Carlos O'Donell
2005-04-09 14:44                       ` John David Anglin
2005-04-09 14:48                         ` Randolph Chung
2005-04-09 23:44                       ` John David Anglin
2005-04-15 14:16                         ` Carlos O'Donell
2005-04-15 15:48                           ` John David Anglin
2005-04-09  0:13                 ` John David Anglin
2005-04-09  6:38                   ` Carlos O'Donell
2005-04-09 15:01                     ` John David Anglin
2005-04-15 14:16                       ` Carlos O'Donell
2005-04-06  1:21     ` John David Anglin
2005-04-06  4:59       ` Carlos O'Donell
2005-04-06  8:42         ` John David Anglin
2005-04-06 16:11           ` John David Anglin
2005-04-06 18:13             ` Carlos O'Donell
2005-04-06 18:37               ` John David Anglin
2005-04-06 19:36                 ` Carlos O'Donell
2005-04-06 19:36                 ` Carlos O'Donell
2005-04-05  9:28 ` [parisc-linux] some other small bitops.h suggestion? Joel Soete
2005-04-13  6:14   ` Grant Grundler
2005-04-13  6:58     ` Joel Soete
2005-04-13 17:47   ` Grant Grundler
     [not found]     ` <20050414013105.GB17749@tausq.org>
2005-04-14  1:33       ` Randolph Chung
2005-04-14  5:07       ` Grant Grundler [this message]
2005-04-14 14:39         ` John David Anglin
2005-04-15 19:27           ` Grant Grundler
2005-04-15 21:41             ` John David Anglin
2005-04-16 17:27               ` Grant Grundler

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