From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 9 Aug 2012 14:24:38 +0000 (-0400)
Subject: urcu: move busy-wait code and name it ___cds_wfq_node_sync_next()
X-Git-Tag: v0.7.4~4
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=b9103f30e18bf81ffbebb6a23215f19f621cd76b;p=userspace-rcu.git

urcu: move busy-wait code and name it ___cds_wfq_node_sync_next()

This code which waits for a node's next pointer until it appears, will
be used many times, move it to a help function and name it
___cds_wfq_node_sync_next().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/urcu/static/wfqueue.h b/urcu/static/wfqueue.h
index 19314f5..636e1af 100644
--- a/urcu/static/wfqueue.h
+++ b/urcu/static/wfqueue.h
@@ -84,6 +84,29 @@ static inline void _cds_wfq_enqueue(struct cds_wfq_queue *q,
 	CMM_STORE_SHARED(*old_tail, node);
 }
 
+/*
+ * Waiting for enqueuer to complete enqueue and return the next node
+ */
+static inline struct cds_wfq_node *
+___cds_wfq_node_sync_next(struct cds_wfq_node *node)
+{
+	struct cds_wfq_node *next;
+	int attempt = 0;
+
+	/*
+	 * Adaptative busy-looping waiting for enqueuer to complete enqueue.
+	 */
+	while ((next = CMM_LOAD_SHARED(node->next)) == NULL) {
+		if (++attempt >= WFQ_ADAPT_ATTEMPTS) {
+			poll(NULL, 0, WFQ_WAIT);	/* Wait for 10ms */
+			attempt = 0;
+		} else
+			caa_cpu_relax();
+	}
+
+	return next;
+}
+
 /*
  * It is valid to reuse and free a dequeued node immediately.
  *
@@ -96,7 +119,6 @@ static inline struct cds_wfq_node *
 ___cds_wfq_dequeue_blocking(struct cds_wfq_queue *q)
 {
 	struct cds_wfq_node *node, *next;
-	int attempt = 0;
 
 	/*
 	 * Queue is empty if it only contains the dummy node.
@@ -105,16 +127,8 @@ ___cds_wfq_dequeue_blocking(struct cds_wfq_queue *q)
 		return NULL;
 	node = q->head;
 
-	/*
-	 * Adaptative busy-looping waiting for enqueuer to complete enqueue.
-	 */
-	while ((next = CMM_LOAD_SHARED(node->next)) == NULL) {
-		if (++attempt >= WFQ_ADAPT_ATTEMPTS) {
-			poll(NULL, 0, WFQ_WAIT);	/* Wait for 10ms */
-			attempt = 0;
-		} else
-			caa_cpu_relax();
-	}
+	next = ___cds_wfq_node_sync_next(node);
+
 	/*
 	 * Move queue head forward.
 	 */