From 0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2 Mon Sep 17 00:00:00 2001 From: Pan Xinhui Date: Tue, 14 Jun 2016 14:37:27 +0800 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner 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 --- kernel/locking/qspinlock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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); -- 2.20.1