X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=urcu-qsbr.c;h=b387536adc6ef923d8254934b41955389002f0fc;hb=4e27f05811113a4444d142811d38e77bcbabbf04;hp=14733ab21e1b61d10bf93ecc082967cdf9d717cd;hpb=90c1618acef5a848409867e9ff2dab7c8b859457;p=userspace-rcu.git

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 14733ab..b387536 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -32,6 +32,7 @@
 #include <errno.h>
 #include <poll.h>
 
+#define BUILD_QSBR_LIB
 #include "urcu-qsbr-static.h"
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #include "urcu-qsbr.h"
@@ -121,8 +122,7 @@ static void wait_for_quiescent_state(void)
 	 */
 	for (index = registry; index < registry + num_readers; index++) {
 #ifndef HAS_INCOHERENT_CACHES
-		while (rcu_gp_ongoing(index->rcu_reader_qs_gp) &&
-		       (*index->rcu_reader_qs_gp - urcu_gp_ctr < 0))
+		while (rcu_gp_ongoing(index->rcu_reader_qs_gp))
 			cpu_relax();
 #else /* #ifndef HAS_INCOHERENT_CACHES */
 		int wait_loops = 0;
@@ -130,8 +130,7 @@ static void wait_for_quiescent_state(void)
 		 * BUSY-LOOP. Force the reader thread to commit its
 		 * rcu_reader_qs_gp update to memory if we wait for too long.
 		 */
-		while (rcu_gp_ongoing(index->rcu_reader_qs_gp) &&
-		       (*index->rcu_reader_qs_gp - urcu_gp_ctr < 0)) {
+		while (rcu_gp_ongoing(index->rcu_reader_qs_gp)) {
 			if (wait_loops++ == KICK_READER_LOOPS) {
 				force_mb_single_thread(index);
 				wait_loops = 0;
@@ -145,12 +144,27 @@ static void wait_for_quiescent_state(void)
 
 void synchronize_rcu(void)
 {
-	internal_urcu_lock();
+	int was_online;
+
+	was_online = rcu_reader_qs_gp & 1;
+
+	/*
+	 * 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)
+		_rcu_thread_offline();
+
 	force_mb_all_threads();
-	urcu_gp_ctr += 2;
+	internal_urcu_lock();
+	STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr + 2);
 	wait_for_quiescent_state();
-	force_mb_all_threads();
 	internal_urcu_unlock();
+	force_mb_all_threads();
+
+	if (was_online)
+		_rcu_thread_online();
 }
 
 /*