From: Russell King <rmk@dyn-67.arm.linux.org.uk>
Date: Mon, 25 May 2009 19:58:00 +0000 (+0100)
Subject: [ARM] barriers: improve xchg, bitops and atomic SMP barriers
X-Git-Tag: v2.6.30-rc8~15^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bac4e960b5ce2453d862beaf20e59aa68af3b43a;p=pandora-kernel.git

[ARM] barriers: improve xchg, bitops and atomic SMP barriers

Mathieu Desnoyers pointed out that the ARM barriers were lacking:

- cmpxchg, xchg and atomic add return need memory barriers on
  architectures which can reorder the relative order in which memory
  read/writes can be seen between CPUs, which seems to include recent
  ARM architectures. Those barriers are currently missing on ARM.

- test_and_xxx_bit were missing SMP barriers.

So put these barriers in.  Provide separate atomic_add/atomic_sub
operations which do not require barriers.

Reported-Reviewed-and-Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

Reading git-diff-tree failed