X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=8381f7b6f61bc892cdf25d671d21ef5b05aae9a5;hp=0e42207e2bcd59d82127dc308def83b85c424798;hb=d486ecdb45ad7b0908b7c4010672af72e5a67caf;hpb=40e140c9f237bbe8c50d4a5355561139f01afb70

diff --git a/urcu.c b/urcu.c
index 0e42207..8381f7b 100644
--- a/urcu.c
+++ b/urcu.c
@@ -98,8 +98,8 @@ static void force_mb_single_thread(pthread_t tid)
 	 * Wait for sighandler (and thus mb()) to execute on every thread.
 	 * BUSY-LOOP.
 	 */
-	while (sig_done < 1)
-		smp_rmb();	/* ensure we re-read sig-done */
+	while (LOAD_REMOTE(sig_done) < 1)
+		cpu_relax();
 	smp_mb();	/* read sig_done before ending the barrier */
 }
 
@@ -113,15 +113,19 @@ static void force_mb_all_threads(void)
 	if (!reader_data)
 		return;
 	sig_done = 0;
-	smp_mb();	/* write sig_done before sending the signals */
+	/*
+	 * pthread_kill has a smp_mb(). But beware, we assume it performs
+	 * a cache flush on architectures with non-coherent cache.
+	 * smp_mb();    write sig_done before sending the signals
+	 */
 	for (index = reader_data; index < reader_data + num_readers; index++)
 		pthread_kill(index->tid, SIGURCU);
 	/*
 	 * Wait for sighandler (and thus mb()) to execute on every thread.
 	 * BUSY-LOOP.
 	 */
-	while (sig_done < num_readers)
-		smp_rmb();	/* ensure we re-read sig-done */
+	while (LOAD_REMOTE(sig_done) < num_readers)
+		cpu_relax();
 	smp_mb();	/* read sig_done before ending the barrier */
 }
 #endif
@@ -152,13 +156,14 @@ void wait_for_quiescent_state(void)
 
 void synchronize_rcu(void)
 {
+	internal_urcu_lock();
+
 	/* All threads should read qparity before accessing data structure
-	 * where new ptr points to. */
+	 * where new ptr points to. Must be done within internal_urcu_lock
+	 * because it iterates on reader threads.*/
 	/* Write new ptr before changing the qparity */
 	force_mb_all_threads();
 
-	internal_urcu_lock();
-
 	switch_next_urcu_qparity();	/* 0 -> 1 */
 
 	/*
@@ -167,7 +172,7 @@ void synchronize_rcu(void)
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
 	 */
-	smp_mb();
+	smp_mc();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
@@ -180,7 +185,7 @@ void synchronize_rcu(void)
 	 * the writer waiting forever while new readers are always accessing
 	 * data (no progress).
 	 */
-	smp_mb();
+	smp_mc();
 
 	switch_next_urcu_qparity();	/* 1 -> 0 */
 
@@ -190,20 +195,19 @@ void synchronize_rcu(void)
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
 	 */
-	smp_mb();
+	smp_mc();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
 	 */
 	wait_for_quiescent_state();	/* Wait readers in parity 1 */
 
-	internal_urcu_unlock();
-
-	/* All threads should finish using the data referred to by old ptr
-	 * before decrementing their urcu_active_readers count */
 	/* Finish waiting for reader threads before letting the old ptr being
-	 * freed. */
+	 * freed. Must be done within internal_urcu_lock because it iterates on
+	 * reader threads. */
 	force_mb_all_threads();
+
+	internal_urcu_unlock();
 }
 
 void urcu_add_reader(pthread_t id)