X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=475bebf526dfd1b9cc8cf78b87d8804ded7a1b6f;hp=8cb32a117bb065405ca3f45e0224dfe8fbebbf5d;hb=2d6debff95ad695255d2ea9d590d1e418590b238;hpb=8895e525a86e679e775b8267546799a0e7bc569f

diff --git a/urcu.c b/urcu.c
index 8cb32a1..475bebf 100644
--- a/urcu.c
+++ b/urcu.c
@@ -23,9 +23,14 @@ pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
  * Global grace period counter.
  * Contains the current RCU_GP_CTR_BIT.
  * Also has a RCU_GP_CTR_BIT of 1, to accelerate the reader fast path.
+ * Written to only by writer with mutex taken. Read by both writer and readers.
  */
 long urcu_gp_ctr = RCU_GP_COUNT;
 
+/*
+ * Written to only by each individual reader. Read by both the reader and the
+ * writers.
+ */
 long __thread urcu_active_readers;
 
 /* Thread IDs of registered readers */
@@ -49,12 +54,17 @@ static int sig_done;
 
 void internal_urcu_lock(void)
 {
+#if 0
 	int ret;
+	/* Mutex sleeping does not play well with busy-waiting loop. */
 	ret = pthread_mutex_lock(&urcu_mutex);
 	if (ret) {
 		perror("Error in pthread mutex lock");
 		exit(-1);
 	}
+#endif
+	while (pthread_mutex_trylock(&urcu_mutex) != 0)
+		cpu_relax();
 }
 
 void internal_urcu_unlock(void)
@@ -73,7 +83,7 @@ void internal_urcu_unlock(void)
  */
 static void switch_next_urcu_qparity(void)
 {
-	urcu_gp_ctr ^= RCU_GP_CTR_BIT;
+	STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR_BIT);
 }
 
 #ifdef DEBUG_FULL_MB
@@ -183,8 +193,8 @@ void synchronize_rcu(void)
 	 * 0 quiescent state. Failure to do so could result in the writer
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
+	 * Ensured by STORE_SHARED and LOAD_SHARED.
 	 */
-	smp_mc();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
@@ -196,8 +206,8 @@ void synchronize_rcu(void)
 	 * committing qparity update to memory. Failure to do so could result in
 	 * the writer waiting forever while new readers are always accessing
 	 * data (no progress).
+	 * Ensured by STORE_SHARED and LOAD_SHARED.
 	 */
-	smp_mc();
 
 	switch_next_urcu_qparity();	/* 1 -> 0 */
 
@@ -206,8 +216,8 @@ void synchronize_rcu(void)
 	 * 1 quiescent state. Failure to do so could result in the writer
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
+	 * Ensured by STORE_SHARED and LOAD_SHARED.
 	 */
-	smp_mc();
 
 	/*
 	 * Wait for previous parity to be empty of readers.