From: Jan Blunck <jblunck@suse.de>
Date: Tue, 16 Jun 2009 22:33:33 +0000 (-0700)
Subject: atomic: only take lock when the counter drops to zero on UP as well
X-Git-Tag: v2.6.31-rc1~299^2~73
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=417dcdf99ec9f8d8d6917189130bdc17cb67c678;p=pandora-kernel.git

atomic: only take lock when the counter drops to zero on UP as well

_atomic_dec_and_lock() should not unconditionally take the lock before
calling atomic_dec_and_test() in the UP case.  For consistency reasons it
should behave exactly like in the SMP case.

Besides that this works around the problem that with CONFIG_DEBUG_SPINLOCK
this spins in __spin_lock_debug() if the lock is already taken even if the
counter doesn't drop to 0.

Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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