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| author | Waiman Long <Waiman.Long@hpe.com> | 2015-09-11 14:37:34 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-09-18 09:27:29 +0200 |
| commit | 93edc8bd7750ff3cae088bfca453ea73dc9004a4 (patch) | |
| tree | 0a2b12864982e91c8a3b2e0cd8fa41c65d6ec3ee /kernel/locking/qspinlock_paravirt.h | |
| parent | c55a6ffa6285e29f874ed403979472631ec70bff (diff) | |
| download | linux-stable-93edc8bd7750ff3cae088bfca453ea73dc9004a4.tar.gz linux-stable-93edc8bd7750ff3cae088bfca453ea73dc9004a4.tar.bz2 linux-stable-93edc8bd7750ff3cae088bfca453ea73dc9004a4.zip | |
locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VAL
If _Q_SLOW_VAL has been set, the vCPU state must have been vcpu_hashed.
The extra check at the end of __pv_queued_spin_unlock() is unnecessary
and can be removed.
Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1441996658-62854-3-git-send-email-Waiman.Long@hpe.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/qspinlock_paravirt.h')
| -rw-r--r-- | kernel/locking/qspinlock_paravirt.h | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index c8e6e9a596f5..f0450ff4829b 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -267,7 +267,6 @@ static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) } if (!lp) { /* ONCE */ - WRITE_ONCE(pn->state, vcpu_hashed); lp = pv_hash(lock, pn); /* @@ -275,11 +274,9 @@ static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) * when we observe _Q_SLOW_VAL in __pv_queued_spin_unlock() * we'll be sure to be able to observe our hash entry. * - * [S] pn->state * [S] <hash> [Rmw] l->locked == _Q_SLOW_VAL * MB RMB * [RmW] l->locked = _Q_SLOW_VAL [L] <unhash> - * [L] pn->state * * Matches the smp_rmb() in __pv_queued_spin_unlock(). */ @@ -364,8 +361,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock) * vCPU is harmless other than the additional latency in completing * the unlock. */ - if (READ_ONCE(node->state) == vcpu_hashed) - pv_kick(node->cpu); + pv_kick(node->cpu); } /* * Include the architecture specific callee-save thunk of the |