sync with rev43

handler/i_s.cc

@@ -2544,6 +2544,8 @@ i_s_innodb_rseg_fill(
 	int	status	= 0;
 	trx_rseg_t*	rseg;
 
+	DBUG_ENTER("i_s_innodb_rseg_fill");
+
 	/* deny access to non-superusers */
 	if (check_global_access(thd, PROCESS_ACL)) {
 

sync/sync0rw.c

@@ -352,6 +352,13 @@ spin_loop:
 				return; /* Success */
 			}
 		}
+
+		/* If wait_ex_waiter stalls, wakes it. */
+		if (lock->wait_ex_waiters && lock->lock_word == RW_LOCK_BIAS) {
+			rw_lock_set_wx_waiters(lock, 0);
+			os_event_set(lock->wait_ex_event);
+			sync_array_object_signalled(sync_primary_wait_array);
+		}
 #else
 		mutex_exit(rw_lock_get_mutex(lock));
 #endif
@@ -447,7 +454,7 @@ rw_lock_x_lock_low(
 	switch(rw_lock_get_writer(lock)) {
 	    case RW_LOCK_WAIT_EX:
 		/* have right to try x-lock */
-		if (lock->lock_word == RW_LOCK_BIAS) {
+retry_x_lock:
 		/* try x-lock */
 		if(__sync_sub_and_fetch(&(lock->lock_word),
 				RW_LOCK_BIAS) == 0) {
@@ -467,12 +474,12 @@ rw_lock_x_lock_low(
 
 			/* Locking succeeded, we may return */
 			return(RW_LOCK_EX);
-			} else {
-				/* fail */
-				__sync_fetch_and_add(&(lock->lock_word),
-					RW_LOCK_BIAS);
-			}
+		} else if(__sync_fetch_and_add(&(lock->lock_word),
+				RW_LOCK_BIAS) == 0) {
+			/* retry x-lock */
+			goto retry_x_lock;
 		}
+
 		/* There are readers, we have to wait */
 		return(RW_LOCK_WAIT_EX);