X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=d1f5d91846af8f8098eacab85a588d945ab9873f;hp=6ba03642f852763057781dcf14bf2ff4a01dc5b9;hb=4c1471decfbd2c3a82c71a967728f3ba096b52c8;hpb=3395d46cc4ab83f9c23ecc5410122111cce5905d

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 6ba0364..d1f5d91 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -1,7 +1,7 @@
 /*
- * urcu.c
+ * urcu-qsbr.c
  *
- * Userspace RCU library
+ * Userspace RCU QSBR library
  *
  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
@@ -32,9 +32,9 @@
 #include <errno.h>
 #include <poll.h>
 
-#include "urcu-qsbr.h"
+#include "urcu-qsbr-static.h"
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
-//#include "urcu.h"
+#include "urcu-qsbr.h"
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -55,7 +55,6 @@ long __thread rcu_reader_qs_gp;
 struct reader_registry {
 	pthread_t tid;
 	long *rcu_reader_qs_gp;
-	char *need_mb;
 };
 
 #ifdef DEBUG_YIELD
@@ -64,10 +63,9 @@ unsigned int __thread rand_yield;
 #endif
 
 static struct reader_registry *registry;
-static char __thread need_mb;
 static int num_readers, alloc_readers;
 
-void internal_urcu_lock(void)
+static void internal_urcu_lock(void)
 {
 	int ret;
 
@@ -84,17 +82,12 @@ void internal_urcu_lock(void)
 			perror("Error in pthread mutex lock");
 			exit(-1);
 		}
-		if (need_mb) {
-			smp_mb();
-			need_mb = 0;
-			smp_mb();
-		}
 		poll(NULL,0,10);
 	}
 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
 }
 
-void internal_urcu_unlock(void)
+static void internal_urcu_unlock(void)
 {
 	int ret;
 
@@ -117,7 +110,7 @@ static void force_mb_all_threads(void)
 	smp_mb();
 }
 
-void wait_for_quiescent_state(void)
+static void wait_for_quiescent_state(void)
 {
 	struct reader_registry *index;
 
@@ -152,12 +145,27 @@ void wait_for_quiescent_state(void)
 
 void synchronize_rcu(void)
 {
+	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();
+
 	internal_urcu_lock();
 	force_mb_all_threads();
 	urcu_gp_ctr += 2;
 	wait_for_quiescent_state();
 	force_mb_all_threads();
 	internal_urcu_unlock();
+
+	if (was_online)
+		_rcu_thread_online();
 }
 
 /*
@@ -200,6 +208,21 @@ void *rcu_publish_content_sym(void **p, void *v)
 	return oldptr;
 }
 
+void rcu_quiescent_state(void)
+{
+	_rcu_quiescent_state();
+}
+
+void rcu_thread_offline(void)
+{
+	_rcu_thread_offline();
+}
+
+void rcu_thread_online(void)
+{
+	_rcu_thread_online();
+}
+
 static void rcu_add_reader(pthread_t id)
 {
 	struct reader_registry *oldarray;
@@ -222,7 +245,6 @@ static void rcu_add_reader(pthread_t id)
 	registry[num_readers].tid = id;
 	/* reference to the TLS of _this_ reader thread. */
 	registry[num_readers].rcu_reader_qs_gp = &rcu_reader_qs_gp;
-	registry[num_readers].need_mb = &need_mb;
 	num_readers++;
 }
 
@@ -254,10 +276,16 @@ void rcu_register_thread(void)
 	internal_urcu_lock();
 	rcu_add_reader(pthread_self());
 	internal_urcu_unlock();
+	_rcu_thread_online();
 }
 
 void rcu_unregister_thread(void)
 {
+	/*
+	 * We have to make the thread offline otherwise we end up dealocking
+	 * with a waiting writer.
+	 */
+	_rcu_thread_offline();
 	internal_urcu_lock();
 	rcu_remove_reader(pthread_self());
 	internal_urcu_unlock();