Commit-ID: 0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2 Gitweb: http://git.kernel.org/tip/0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2 Author: Pan Xinhui <[email protected]> AuthorDate: Tue, 14 Jun 2016 14:37:27 +0800 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 27 Jun 2016 11:37:41 +0200
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 <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] [ Rewrote changelog. ] Signed-off-by: Ingo Molnar <[email protected]> --- 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 7306555..b2caec7 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);
