locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock()
authorPan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Mon, 19 Sep 2016 09:23:52 +0000 (05:23 -0400)
committerIngo Molnar <mingo@kernel.org>
Thu, 22 Sep 2016 13:25:51 +0000 (15:25 +0200)
commitb193049375b04df3ada8c3347b7083db95918bc3
treee72b1e31ee8d3b04008b13313b89fe44b1d95d3e
parent7cf0f1426a909ed36a8b349a4a975e0d68b5edad
locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock()

cmpxchg_release() is more lighweight than cmpxchg() on some archs(e.g.
PPC), moreover, in __pv_queued_spin_unlock() we only needs a RELEASE in
the fast path(pairing with *_try_lock() or *_lock()). And the slow path
has smp_store_release too. So it's safe to use cmpxchg_release here.

Suggested-by: Boqun Feng <boqun.feng@gmail.com>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: virtualization@lists.linux-foundation.org
Cc: waiman.long@hpe.com
Link: http://lkml.kernel.org/r/1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/locking/qspinlock_paravirt.h