X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=3b9a054b40b1bc61f29768bf5d4085d62a8b7bd9;hp=a86f6e94d5ae13eb24e5d34610a3d9c5954373b4;hb=bc49c323c92d6809e534fd0bb78309922c1cd2bb;hpb=47d2f29ead2c92123069ebf7b84c6e48cf91612a

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index a86f6e9..3b9a054 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -135,12 +135,24 @@ static void switch_next_urcu_qparity(void)
 
 void synchronize_rcu(void)
 {
+	unsigned long was_online;
+
+	was_online = rcu_reader_qs_gp;
+
 	/* All threads should read qparity before accessing data structure
 	 * where new ptr points to.
 	 */
 	/* Write new ptr before changing the qparity */
 	smp_mb();
 
+	/*
+	 * Mark the writer thread offline to make sure we don't wait for
+	 * our own quiescent state. This allows using synchronize_rcu() in
+	 * threads registered as readers.
+	 */
+	if (was_online)
+		STORE_SHARED(rcu_reader_qs_gp, 0);
+
 	internal_urcu_lock();
 
 	switch_next_urcu_qparity();	/* 0 -> 1 */
@@ -183,9 +195,12 @@ void synchronize_rcu(void)
 
 	internal_urcu_unlock();
 
-	/* Finish waiting for reader threads before letting the old ptr being
+	/*
+	 * Finish waiting for reader threads before letting the old ptr being
 	 * freed.
 	 */
+	if (was_online)
+		_STORE_SHARED(rcu_reader_qs_gp, LOAD_SHARED(urcu_gp_ctr));
 	smp_mb();
 }
 #else /* !(BITS_PER_LONG < 64) */