From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Sat, 26 Sep 2009 22:29:37 +0000 (-0400)
Subject: qsbr: only mark reader thread as being waited for in contended case
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=refs%2Fheads%2Furcu%2Fyield;p=userspace-rcu.git

qsbr: only mark reader thread as being waited for in contended case

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index c275b66..ad3d17a 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -114,6 +114,9 @@ static void wait_for_quiescent_state(void)
 	for (index = registry; index < registry + num_readers; index++) {
 		int wait_loops = 0;
 
+		if (likely(!rcu_gp_ongoing(&index->urcu_reader_status->qs_gp)))
+			continue;
+	
 		index->urcu_reader_status->gp_waiting = 1;
 		while (rcu_gp_ongoing(&index->urcu_reader_status->qs_gp)) {
 			if (wait_loops++ == RCU_QS_ACTIVE_ATTEMPTS) {