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authorMark Rutland <mark.rutland@arm.com>2017-10-23 14:07:29 -0700
committerIngo Molnar <mingo@kernel.org>2017-10-25 11:01:08 +0200
commit6aa7de059173a986114ac43b8f50b297a86f09a8 (patch)
tree77666afe795e022914ca26433d61686c694dc4fd /arch/s390/lib
parentb03a0fe0c5e4b46dcd400d27395b124499554a71 (diff)
locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()
Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/s390/lib')
-rw-r--r--arch/s390/lib/spinlock.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index b12663d653d8..34e30b9ea234 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -162,8 +162,8 @@ void _raw_read_lock_wait(arch_rwlock_t *rw)
smp_yield_cpu(~owner);
count = spin_retry;
}
- old = ACCESS_ONCE(rw->lock);
- owner = ACCESS_ONCE(rw->owner);
+ old = READ_ONCE(rw->lock);
+ owner = READ_ONCE(rw->owner);
if (old < 0)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
@@ -178,7 +178,7 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw)
int old;
while (count-- > 0) {
- old = ACCESS_ONCE(rw->lock);
+ old = READ_ONCE(rw->lock);
if (old < 0)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
@@ -202,8 +202,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, int prev)
smp_yield_cpu(~owner);
count = spin_retry;
}
- old = ACCESS_ONCE(rw->lock);
- owner = ACCESS_ONCE(rw->owner);
+ old = READ_ONCE(rw->lock);
+ owner = READ_ONCE(rw->owner);
smp_mb();
if (old >= 0) {
prev = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
@@ -230,8 +230,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
smp_yield_cpu(~owner);
count = spin_retry;
}
- old = ACCESS_ONCE(rw->lock);
- owner = ACCESS_ONCE(rw->owner);
+ old = READ_ONCE(rw->lock);
+ owner = READ_ONCE(rw->owner);
if (old >= 0 &&
__atomic_cmpxchg_bool(&rw->lock, old, old | 0x80000000))
prev = old;
@@ -251,7 +251,7 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw)
int old;
while (count-- > 0) {
- old = ACCESS_ONCE(rw->lock);
+ old = READ_ONCE(rw->lock);
if (old)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000))