From 2aa79af64263190eec610422b07f60e99a7d230a Mon Sep 17 00:00:00 2001 From: "Peter Zijlstra (Intel)" Date: Fri, 24 Apr 2015 14:56:36 -0400 Subject: locking/qspinlock: Revert to test-and-set on hypervisors When we detect a hypervisor (!paravirt, see qspinlock paravirt support patches), revert to a simple test-and-set lock to avoid the horrors of queue preemption. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Daniel J Blueman Cc: David Vrabel Cc: Douglas Hatch Cc: H. Peter Anvin Cc: Konrad Rzeszutek Wilk Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Paolo Bonzini Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Raghavendra K T Cc: Rik van Riel Cc: Scott J Norton Cc: Thomas Gleixner Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-8-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar --- kernel/locking/qspinlock.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/locking') diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 033872113ebb..fd31a474145d 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -249,6 +249,9 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) BUILD_BUG_ON(CONFIG_NR_CPUS >= (1U << _Q_TAIL_CPU_BITS)); + if (virt_queued_spin_lock(lock)) + return; + /* * wait for in-progress pending->locked hand-overs * -- cgit