From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 10 Jun 2011 13:08:55 +0000 (+0200)
Subject: sched: Simplify mutex_spin_on_owner()
X-Git-Tag: v3.1-rc1~298^2~16
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=307bf9803f25a8a3f53c1012110fb74e2f893eb0;p=pandora-kernel.git

sched: Simplify mutex_spin_on_owner()

It does not make sense to rcu_read_lock/unlock() in every loop
iteration while spinning on the mutex.

Move the rcu protection outside the loop. Also simplify the
return path to always check for lock->owner == NULL which
meets the requirements of both owner changed and need_resched()
caused loop exits.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1106101458350.11814@ionos
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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