From: Will Deacon <will.deacon@arm.com>
To: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org, peterz@infradead.org,
mingo@kernel.org, boqun.feng@gmail.com,
paulmck@linux.vnet.ibm.com, longman@redhat.com,
Will Deacon <will.deacon@arm.com>
Subject: [PATCH v2 06/13] locking/qspinlock: Use atomic_cond_read_acquire
Date: Wed, 11 Apr 2018 19:01:13 +0100 [thread overview]
Message-ID: <1523469680-17699-7-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1523469680-17699-1-git-send-email-will.deacon@arm.com>
Rather than dig into the counter field of the atomic_t inside the
qspinlock structure so that we can call smp_cond_load_acquire, use
atomic_cond_read_acquire instead, which operates on the atomic_t
directly.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
kernel/locking/qspinlock.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 01b660442d87..648a16a2cd23 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -377,8 +377,8 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
* barriers.
*/
if (val & _Q_LOCKED_MASK) {
- smp_cond_load_acquire(&lock->val.counter,
- !(VAL & _Q_LOCKED_MASK));
+ atomic_cond_read_acquire(&lock->val,
+ !(VAL & _Q_LOCKED_MASK));
}
/*
@@ -481,8 +481,8 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
*
* The PV pv_wait_head_or_lock function, if active, will acquire
* the lock and return a non-zero value. So we have to skip the
- * smp_cond_load_acquire() call. As the next PV queue head hasn't been
- * designated yet, there is no way for the locked value to become
+ * atomic_cond_read_acquire() call. As the next PV queue head hasn't
+ * been designated yet, there is no way for the locked value to become
* _Q_SLOW_VAL. So both the set_locked() and the
* atomic_cmpxchg_relaxed() calls will be safe.
*
@@ -492,7 +492,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
if ((val = pv_wait_head_or_lock(lock, node)))
goto locked;
- val = smp_cond_load_acquire(&lock->val.counter, !(VAL & _Q_LOCKED_PENDING_MASK));
+ val = atomic_cond_read_acquire(&lock->val, !(VAL & _Q_LOCKED_PENDING_MASK));
locked:
/*
@@ -509,7 +509,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
/* In the PV case we might already have _Q_LOCKED_VAL set */
if ((val & _Q_TAIL_MASK) == tail) {
/*
- * The smp_cond_load_acquire() call above has provided the
+ * The atomic_cond_read_acquire() call above has provided the
* necessary acquire semantics required for locking.
*/
old = atomic_cmpxchg_relaxed(&lock->val, val, _Q_LOCKED_VAL);
--
2.1.4
next prev parent reply other threads:[~2018-04-11 18:02 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 18:01 [PATCH v2 00/13] kernel/locking: qspinlock improvements Will Deacon
2018-04-11 18:01 ` [PATCH v2 01/13] barriers: Introduce smp_cond_load_relaxed and atomic_cond_read_relaxed Will Deacon
2018-04-11 18:01 ` [PATCH v2 02/13] locking/qspinlock: Bound spinning on pending->locked transition in slowpath Will Deacon
2018-04-11 18:01 ` [PATCH v2 03/13] locking/qspinlock/x86: Increase _Q_PENDING_LOOPS upper bound Will Deacon
2018-04-11 18:01 ` [PATCH v2 04/13] locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath Will Deacon
2018-04-11 19:34 ` Waiman Long
2018-04-11 20:35 ` Waiman Long
2018-04-11 19:53 ` Waiman Long
2018-04-12 14:06 ` Will Deacon
2018-04-12 14:16 ` Waiman Long
2018-04-12 14:18 ` Will Deacon
2018-04-11 18:01 ` [PATCH v2 05/13] locking/qspinlock: Kill cmpxchg loop when claiming lock from head of queue Will Deacon
2018-04-11 18:01 ` Will Deacon [this message]
2018-04-11 18:01 ` [PATCH v2 07/13] locking/mcs: Use smp_cond_load_acquire() in mcs spin loop Will Deacon
2018-04-11 18:01 ` [PATCH v2 08/13] locking/qspinlock: Use smp_cond_load_relaxed to wait for next node Will Deacon
2018-04-11 18:01 ` [PATCH v2 09/13] locking/qspinlock: Merge struct __qspinlock into struct qspinlock Will Deacon
2018-04-11 19:13 ` Waiman Long
2018-04-11 18:01 ` [PATCH v2 10/13] locking/qspinlock: Make queued_spin_unlock use smp_store_release Will Deacon
2018-04-11 18:01 ` [PATCH v2 11/13] locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() Will Deacon
2018-04-11 18:01 ` [PATCH v2 12/13] locking/qspinlock: Use try_cmpxchg instead of cmpxchg when locking Will Deacon
2018-04-11 18:01 ` [PATCH v2 13/13] locking/qspinlock: Add stat tracking for pending vs slowpath Will Deacon
2018-04-13 9:24 ` [PATCH v2 00/13] kernel/locking: qspinlock improvements Catalin Marinas
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