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Subject[tip:locking/core] locking/qspinlock: Use atomic_cond_read_acquire()
Commit-ID:  f9c811fac48cfbbfb452b08d1042386947868d07
Gitweb: https://git.kernel.org/tip/f9c811fac48cfbbfb452b08d1042386947868d07
Author: Will Deacon <will.deacon@arm.com>
AuthorDate: Thu, 26 Apr 2018 11:34:21 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 27 Apr 2018 09:48:49 +0200

locking/qspinlock: Use atomic_cond_read_acquire()

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.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1524738868-31318-8-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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 b51494a50b1e..56af1fa9874d 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -337,8 +337,8 @@ 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));
}

/*
@@ -441,8 +441,8 @@ queue:
*
* 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.
*
@@ -452,7 +452,7 @@ queue:
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:
/*
@@ -469,7 +469,7 @@ locked:
/* 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);
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