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Fixup the atomic code in pthread_rwlock branch of lib/isc/rwlock.c

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This commit is contained in:
Ondřej Surý 2019-06-04 10:10:46 +02:00 committed by Evan Hunt
parent 48f16f223c
commit 1e2f40d01b
1 changed files with 6 additions and 5 deletions
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11
lib/isc/rwlock.c
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@ -53,10 +53,10 @@ isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
while (true) {
REQUIRE(pthread_rwlock_wrlock(&rwl->rwlock) == 0);
/* Unlock if in middle of downgrade operation */
if (atomic_load_release(&rwl->downgrade)) {
if (atomic_load_acquire(&rwl->downgrade)) {
REQUIRE(pthread_rwlock_unlock(&rwl->rwlock)
== 0);
while (atomic_load(&rwl->downgrade));
while (atomic_load_acquire(&rwl->downgrade));
continue;
}
break;
@ -78,7 +78,7 @@ isc_rwlock_trylock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
break;
case isc_rwlocktype_write:
ret = pthread_rwlock_trywrlock(&rwl->rwlock);
if ((ret == 0) && atomic_load(&rwl->downgrade)) {
if ((ret == 0) && atomic_load_acquire(&rwl->downgrade)) {
isc_rwlock_unlock(rwl, type);
return (ISC_R_LOCKBUSY);
}
@ -104,15 +104,16 @@ isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
isc_result_t
isc_rwlock_tryupgrade(isc_rwlock_t *rwl) {
UNUSED(rwl);
return (ISC_R_LOCKBUSY);
}
void
isc_rwlock_downgrade(isc_rwlock_t *rwl) {
atomic_store_acquire(&rwl->downgrade, true);
atomic_store_release(&rwl->downgrade, true);
isc_rwlock_unlock(rwl, isc_rwlocktype_write);
isc_rwlock_lock(rwl, isc_rwlocktype_read);
atomic_store_acquire(&rwl->downgrade, false);
atomic_store_release(&rwl->downgrade, false);
}
void