From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Sat, 23 Feb 2008 21:03:29 +0000 (+0300)
Subject: documentation: atomic_add_unless() doesn't imply mb() on failure
X-Git-Tag: v2.6.25-rc3~15
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02c608c1fefe821a4c6fc34c45a0dea3cebf4764;p=pandora-kernel.git

documentation: atomic_add_unless() doesn't imply mb() on failure

(sorry for being offtpoic, but while experts are here...)

A "typical" implementation of atomic_add_unless() can return 0 immediately
after the first atomic_read() (before doing cmpxchg). In that case it doesn't
provide any barrier semantics. See include/asm-ia64/atomic.h as an example.

We should either change the implementation, or fix the docs.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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