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Groups > linux.kernel > #1486145
| From | Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v7 1/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock |
| Date | 2016-09-19 07:30 +0200 |
| Message-ID | <siZjs-1jp-21@gated-at.bofh.it> (permalink) |
| References | <siZjr-1jp-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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> --- kernel/locking/qspinlock_paravirt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 8a99abf..ce655aa 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -544,7 +544,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock) * unhash. Otherwise it would be possible to have multiple @lock * entries, which would be BAD. */ - locked = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0); + locked = cmpxchg_release(&l->locked, _Q_LOCKED_VAL, 0); if (likely(locked == _Q_LOCKED_VAL)) return; -- 2.4.11
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[PATCH v7 0/6] Implement qspinlock/pv-qspinlock on ppc Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-09-19 07:30 +0200
[PATCH v7 3/6] powerpc: pseries/Kconfig: Add qspinlock build config Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-09-19 07:30 +0200
[PATCH v7 1/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-09-19 07:30 +0200
[tip:locking/core] locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock() tip-bot for Pan Xinhui <tipbot@zytor.com> - 2016-09-22 16:10 +0200
[PATCH v7 2/6] powerpc/qspinlock: powerpc support qspinlock Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-09-19 07:30 +0200
[PATCH v7 4/6] powerpc: lib/locks.c: Add cpu yield/wake helper function Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-09-19 07:30 +0200
Re: [PATCH v7 4/6] powerpc: lib/locks.c: Add cpu yield/wake helper function Boqun Feng <boqun.feng@gmail.com> - 2016-09-22 17:20 +0200
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