diff options
| -rw-r--r-- | src/third_party/wiredtiger/src/include/mutex.i | 12 | ||||
| -rw-r--r-- | src/third_party/wiredtiger/src/support/mtx_rw.c | 37 |
2 files changed, 38 insertions, 11 deletions
diff --git a/src/third_party/wiredtiger/src/include/mutex.i b/src/third_party/wiredtiger/src/include/mutex.i index 52250f84ab3..65956c13c08 100644 --- a/src/third_party/wiredtiger/src/include/mutex.i +++ b/src/third_party/wiredtiger/src/include/mutex.i @@ -306,6 +306,12 @@ __wt_fair_lock(WT_SESSION_IMPL *session, WT_FAIR_LOCK *lock) __wt_sleep(0, 10); } + /* + * Applications depend on a barrier here so that operations holding the + * lock see consistent data. + */ + WT_READ_BARRIER(); + return (0); } @@ -319,6 +325,12 @@ __wt_fair_unlock(WT_SESSION_IMPL *session, WT_FAIR_LOCK *lock) WT_UNUSED(session); /* + * Ensure that all updates made while the lock was held are visible to + * the next thread to acquire the lock. + */ + WT_WRITE_BARRIER(); + + /* * We have exclusive access - the update does not need to be atomic. */ ++lock->fair_lock_owner; diff --git a/src/third_party/wiredtiger/src/support/mtx_rw.c b/src/third_party/wiredtiger/src/support/mtx_rw.c index b6876cdfbdc..dbf73bb4f13 100644 --- a/src/third_party/wiredtiger/src/support/mtx_rw.c +++ b/src/third_party/wiredtiger/src/support/mtx_rw.c @@ -183,6 +183,8 @@ __wt_readlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock) session, WT_VERB_MUTEX, "rwlock: readlock %s", rwlock->name)); WT_STAT_FAST_CONN_INCR(session, rwlock_read); + WT_DIAGNOSTIC_YIELD; + l = &rwlock->rwlock; /* @@ -213,6 +215,12 @@ __wt_readlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock) */ ++l->s.readers; + /* + * Applications depend on a barrier here so that operations holding the + * lock see consistent data. + */ + WT_READ_BARRIER(); + return (0); } @@ -306,6 +314,12 @@ __wt_writelock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock) __wt_sleep(0, 10); } + /* + * Applications depend on a barrier here so that operations holding the + * lock see consistent data. + */ + WT_READ_BARRIER(); + return (0); } @@ -316,31 +330,32 @@ __wt_writelock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock) int __wt_writeunlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock) { - wt_rwlock_t *l, copy; + wt_rwlock_t *l, new; WT_RET(__wt_verbose( session, WT_VERB_MUTEX, "rwlock: writeunlock %s", rwlock->name)); + /* + * Ensure that all updates made while the lock was held are visible to + * the next thread to acquire the lock. + */ + WT_WRITE_BARRIER(); + l = &rwlock->rwlock; - copy = *l; + new = *l; /* * We're the only writer of the writers/readers fields, so the update * does not need to be atomic; we have to update both values at the * same time though, otherwise we'd potentially race with the thread * next granted the lock. - * - * Use a memory barrier to ensure the compiler doesn't mess with these - * instructions and rework the code in a way that avoids the update as - * a unit. */ - WT_BARRIER(); - - ++copy.s.writers; - ++copy.s.readers; + ++new.s.writers; + ++new.s.readers; + l->i.wr = new.i.wr; - l->i.wr = copy.i.wr; + WT_DIAGNOSTIC_YIELD; return (0); } |