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authorPan Xinhui <xinhui.pan@linux.vnet.ibm.com>2016-06-14 14:37:27 +0800
committerIngo Molnar <mingo@kernel.org>2016-06-27 11:37:41 +0200
commit0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2 (patch)
tree901f7641d6bc6ed48fdffaee6f85f155e0fb8a07
parentebff09a6ff164aec2b33bf1f9a488c45ac108413 (diff)
downloadlinux-0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2.tar.bz2
locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec()
queued_spin_lock_slowpath() should not worry about another queued_spin_lock_slowpath() running in interrupt context and changing node->count by accident, because node->count keeps the same value every time we enter/leave queued_spin_lock_slowpath(). On some architectures this_cpu_dec() will save/restore irq flags, which has high overhead. Use the much cheaper __this_cpu_dec() instead. Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hpe.com Link: http://lkml.kernel.org/r/1465886247-3773-1-git-send-email-xinhui.pan@linux.vnet.ibm.com [ Rewrote changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/locking/qspinlock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 730655533440..b2caec7315af 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -619,7 +619,7 @@ release:
/*
* release the node
*/
- this_cpu_dec(mcs_nodes[0].count);
+ __this_cpu_dec(mcs_nodes[0].count);
}
EXPORT_SYMBOL(queued_spin_lock_slowpath);