X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-defer-impl.h;h=4d1ca5e4e63085f4dbe24f7284361e9879e46e4b;hp=4211f7c76954c2fc1bfd088ac0497cb2a34516a9;hb=a641253675b6005329234c0c7354b88dea7a4245;hpb=d7ff6cee89d7f8b4183b783d3d0a337b27d10bd2

diff --git a/urcu-defer-impl.h b/urcu-defer-impl.h
index 4211f7c..4d1ca5e 100644
--- a/urcu-defer-impl.h
+++ b/urcu-defer-impl.h
@@ -61,7 +61,9 @@
  * Assumes that (void *)-2L is not used often. Used to encode non-aligned
  * functions and non-aligned data using extra space.
  * We encode the (void *)-2L fct as: -2L, fct, data.
- * We encode the (void *)-2L data as: -2L, fct, data.
+ * We encode the (void *)-2L data as either:
+ *   fct | DQ_FCT_BIT, data (if fct is aligned), or
+ *   -2L, fct, data (if fct is not aligned).
  * Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
  */
 #define DQ_FCT_BIT		(1 << 0)
@@ -159,7 +161,7 @@ static void mutex_lock_defer(pthread_mutex_t *mutex)
  */
 static void wake_up_defer(void)
 {
-	if (unlikely(uatomic_read(&defer_thread_futex) == -1)) {
+	if (caa_unlikely(uatomic_read(&defer_thread_futex) == -1)) {
 		uatomic_set(&defer_thread_futex, 0);
 		futex_noasync(&defer_thread_futex, FUTEX_WAKE, 1,
 		      NULL, NULL, 0);
@@ -223,11 +225,11 @@ static void rcu_defer_barrier_queue(struct defer_queue *queue,
 	for (i = queue->tail; i != head;) {
 		cmm_smp_rmb();       /* read head before q[]. */
 		p = CMM_LOAD_SHARED(queue->q[i++ & DEFER_QUEUE_MASK]);
-		if (unlikely(DQ_IS_FCT_BIT(p))) {
+		if (caa_unlikely(DQ_IS_FCT_BIT(p))) {
 			DQ_CLEAR_FCT_BIT(p);
 			queue->last_fct_out = p;
 			p = CMM_LOAD_SHARED(queue->q[i++ & DEFER_QUEUE_MASK]);
-		} else if (unlikely(p == DQ_FCT_MARK)) {
+		} else if (caa_unlikely(p == DQ_FCT_MARK)) {
 			p = CMM_LOAD_SHARED(queue->q[i++ & DEFER_QUEUE_MASK]);
 			queue->last_fct_out = p;
 			p = CMM_LOAD_SHARED(queue->q[i++ & DEFER_QUEUE_MASK]);
@@ -245,7 +247,7 @@ static void _rcu_defer_barrier_thread(void)
 
 	head = defer_queue.head;
 	num_items = head - defer_queue.tail;
-	if (unlikely(!num_items))
+	if (caa_unlikely(!num_items))
 		return;
 	synchronize_rcu();
 	rcu_defer_barrier_queue(&defer_queue, head);
@@ -284,7 +286,7 @@ void rcu_defer_barrier(void)
 		index->last_head = CMM_LOAD_SHARED(index->head);
 		num_items += index->last_head - index->tail;
 	}
-	if (likely(!num_items)) {
+	if (caa_likely(!num_items)) {
 		/*
 		 * We skip the grace period because there are no queued
 		 * callbacks to execute.
@@ -316,20 +318,33 @@ void _defer_rcu(void (*fct)(void *p), void *p)
 	 * If queue is full, or reached threshold. Empty queue ourself.
 	 * Worse-case: must allow 2 supplementary entries for fct pointer.
 	 */
-	if (unlikely(head - tail >= DEFER_QUEUE_SIZE - 2)) {
+	if (caa_unlikely(head - tail >= DEFER_QUEUE_SIZE - 2)) {
 		assert(head - tail <= DEFER_QUEUE_SIZE);
 		rcu_defer_barrier_thread();
 		assert(head - CMM_LOAD_SHARED(defer_queue.tail) == 0);
 	}
 
-	if (unlikely(defer_queue.last_fct_in != fct)) {
+	/*
+	 * Encode:
+	 * if the function is not changed and the data is aligned and it is
+	 * not the marker:
+	 *	store the data
+	 * otherwise if the function is aligned and its not the marker:
+	 *	store the function with DQ_FCT_BIT
+	 *	store the data
+	 * otherwise:
+	 *	store the marker (DQ_FCT_MARK)
+	 *	store the function
+	 *	store the data
+	 *
+	 * Decode: see the comments before 'struct defer_queue'
+	 *         or the code in rcu_defer_barrier_queue().
+	 */
+	if (caa_unlikely(defer_queue.last_fct_in != fct
+			|| DQ_IS_FCT_BIT(p)
+			|| p == DQ_FCT_MARK)) {
 		defer_queue.last_fct_in = fct;
-		if (unlikely(DQ_IS_FCT_BIT(fct) || fct == DQ_FCT_MARK)) {
-			/*
-			 * If the function to encode is not aligned or the
-			 * marker, write DQ_FCT_MARK followed by the function
-			 * pointer.
-			 */
+		if (caa_unlikely(DQ_IS_FCT_BIT(fct) || fct == DQ_FCT_MARK)) {
 			_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK],
 				      DQ_FCT_MARK);
 			_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK],
@@ -339,17 +354,6 @@ void _defer_rcu(void (*fct)(void *p), void *p)
 			_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK],
 				      fct);
 		}
-	} else {
-		if (unlikely(DQ_IS_FCT_BIT(p) || p == DQ_FCT_MARK)) {
-			/*
-			 * If the data to encode is not aligned or the marker,
-			 * write DQ_FCT_MARK followed by the function pointer.
-			 */
-			_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK],
-				      DQ_FCT_MARK);
-			_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK],
-				      fct);
-		}
 	}
 	_CMM_STORE_SHARED(defer_queue.q[head++ & DEFER_QUEUE_MASK], p);
 	cmm_smp_wmb();	/* Publish new pointer before head */