From: Ralf Baechle <ralf@linux-mips.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Russell King <rmk+lkml@arm.linux.org.uk>,
Christoph Lameter <clameter@sgi.com>,
David Howells <dhowells@redhat.com>,
torvalds@osdl.org, akpm@osdl.org,
linux-arm-kernel@lists.arm.linux.org.uk,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
Date: Thu, 7 Dec 2006 16:51:42 +0000 [thread overview]
Message-ID: <20061207165142.GA9006@linux-mips.org> (raw)
In-Reply-To: <4577DF5C.5070701@yahoo.com.au>
On Thu, Dec 07, 2006 at 08:31:08PM +1100, Nick Piggin wrote:
> Wrong. Your ll/sc implementation with cmpxchg is buggy. The cmpxchg
> load_locked is not locked at all, and there can be interleaving writes
> between the load and cmpxchg which do not cause the store_conditional
> to fail.
>
> It might be reasonable to implement this watered down version, but:
> don't some architectures have restrictions on what instructions can
> be issued between the ll and the sc?
On MIPS the restriction is no loads or stores or sync instructions between
ll/sc. Also there may be at most 2048 bytes between the address of the
ll and sc instructions. Which means ll/sc sequences should better be
written in assembler or gcc might do a bit too creative things ...
Ralf
next prev parent reply other threads:[~2006-12-07 16:51 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-06 16:43 [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it David Howells
2006-12-06 17:21 ` Linus Torvalds
2006-12-06 18:56 ` Christoph Lameter
2006-12-06 19:00 ` Russell King
2006-12-06 19:16 ` Christoph Lameter
2006-12-06 19:28 ` Linus Torvalds
2006-12-06 19:58 ` Russell King
2006-12-06 21:36 ` Matthew Wilcox
2006-12-06 21:52 ` Christoph Lameter
2006-12-06 22:05 ` Matthew Wilcox
2006-12-06 22:15 ` Christoph Lameter
2006-12-07 0:37 ` Roman Zippel
2006-12-07 0:54 ` Linus Torvalds
2006-12-07 1:05 ` Roman Zippel
2006-12-07 1:18 ` Linus Torvalds
2006-12-07 1:24 ` Roman Zippel
2006-12-07 1:36 ` Linus Torvalds
2006-12-07 1:44 ` Matthew Wilcox
2006-12-07 2:09 ` Douglas McNaught
2006-12-07 1:52 ` Roman Zippel
2006-12-07 9:23 ` Nick Piggin
2006-12-06 22:38 ` Linus Torvalds
2006-12-07 9:31 ` Nick Piggin
2006-12-07 13:20 ` Ivan Kokshaysky
2006-12-07 15:03 ` Russell King
2006-12-08 1:18 ` Nick Piggin
2006-12-08 8:56 ` Russell King
2006-12-08 16:06 ` Christoph Lameter
2006-12-08 16:31 ` Russell King
2006-12-08 16:43 ` Christoph Lameter
2006-12-08 16:47 ` Russell King
2006-12-08 16:53 ` Christoph Lameter
2006-12-08 16:58 ` Russell King
2006-12-08 16:56 ` David Howells
2006-12-08 17:06 ` Christoph Lameter
2006-12-08 17:18 ` Russell King
2006-12-08 17:23 ` Christoph Lameter
2006-12-08 19:15 ` Linus Torvalds
2006-12-08 19:31 ` Russell King
2006-12-08 19:37 ` Linus Torvalds
2006-12-08 19:43 ` Russell King
2006-12-08 20:01 ` Linus Torvalds
2006-12-08 18:46 ` Linus Torvalds
2006-12-08 19:04 ` Russell King
2006-12-08 19:35 ` Linus Torvalds
2006-12-08 19:59 ` Russell King
2006-12-08 20:34 ` Linus Torvalds
2006-12-11 11:04 ` David Howells
2006-12-08 22:33 ` Nick Piggin
2006-12-07 15:36 ` Linus Torvalds
2006-12-07 16:51 ` Ralf Baechle [this message]
2006-12-07 0:46 ` Ralf Baechle
2006-12-06 19:05 ` Linus Torvalds
2006-12-06 19:08 ` Al Viro
2006-12-06 19:25 ` Linus Torvalds
2006-12-06 19:29 ` Matthew Wilcox
2006-12-06 19:43 ` David Howells
2006-12-06 19:54 ` Linus Torvalds
2006-12-06 19:56 ` Linus Torvalds
2006-12-07 1:09 ` David Miller
2006-12-06 19:26 ` Matthew Wilcox
2006-12-06 19:29 ` Christoph Lameter
2006-12-06 19:36 ` Matthew Wilcox
2006-12-06 19:47 ` Christoph Lameter
2006-12-06 19:50 ` Matthew Wilcox
2006-12-06 20:11 ` Christoph Lameter
2006-12-06 20:17 ` Matthew Wilcox
2006-12-06 19:34 ` Linus Torvalds
2006-12-06 19:41 ` Matthew Wilcox
2006-12-06 19:45 ` David Howells
2006-12-06 20:00 ` Russell King
2006-12-07 15:06 ` Russell King
2006-12-08 15:32 ` Russell King
2006-12-06 19:12 ` Lennert Buytenhek
2006-12-06 19:47 ` David Howells
2006-12-06 20:09 ` Lennert Buytenhek
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