X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=53c7f37677f762280b2a6337a6820bdf22c55faf;hp=08fb75dd0feae13421647f7d84615bee6d88654f;hb=6e32665beaad7fef48e9ab3c8c4cda2e9c232dde;hpb=c265818b951224bcde407b1efa14f9daf44949b3

diff --git a/urcu.c b/urcu.c
index 08fb75d..53c7f37 100644
--- a/urcu.c
+++ b/urcu.c
@@ -19,10 +19,10 @@
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-/* Global quiescent period parity */
-int urcu_qparity;
+/* Global grace period counter */
+long urcu_gp_ctr;
 
-int __thread urcu_active_readers[2];
+long __thread urcu_active_readers;
 
 /* Thread IDs of registered readers */
 #define INIT_NUM_THREADS 4
@@ -32,6 +32,11 @@ struct reader_data {
 	int *urcu_active_readers;
 };
 
+#ifdef DEBUG_YIELD
+unsigned int yield_active;
+unsigned int __thread rand_yield;
+#endif
+
 static struct reader_data *reader_data;
 static int num_readers, alloc_readers;
 static int sig_done;
@@ -60,11 +65,9 @@ void internal_urcu_unlock(void)
 /*
  * called with urcu_mutex held.
  */
-static int switch_next_urcu_qparity(void)
+static void switch_next_urcu_qparity(void)
 {
-	int old_parity = urcu_qparity;
-	urcu_qparity = 1 - old_parity;
-	return old_parity;
+	urcu_gp_ctr ^= RCU_GP_CTR_BIT;
 }
 
 static void force_mb_all_threads(void)
@@ -76,20 +79,27 @@ static void force_mb_all_threads(void)
 	 */
 	if (!reader_data)
 		return;
+	debug_yield_write();
 	sig_done = 0;
+	debug_yield_write();
 	mb();	/* write sig_done before sending the signals */
-	for (index = reader_data; index < reader_data + num_readers; index++)
+	debug_yield_write();
+	for (index = reader_data; index < reader_data + num_readers; index++) {
 		pthread_kill(index->tid, SIGURCU);
+		debug_yield_write();
+	}
 	/*
 	 * Wait for sighandler (and thus mb()) to execute on every thread.
 	 * BUSY-LOOP.
 	 */
 	while (sig_done < num_readers)
 		barrier();
+	debug_yield_write();
 	mb();	/* read sig_done before ending the barrier */
+	debug_yield_write();
 }
 
-void wait_for_quiescent_state(int parity)
+void wait_for_quiescent_state(void)
 {
 	struct reader_data *index;
 
@@ -101,7 +111,7 @@ void wait_for_quiescent_state(int parity)
 		/*
 		 * BUSY-LOOP.
 		 */
-		while (index->urcu_active_readers[parity] != 0)
+		while (rcu_old_gp_ongoing(index->urcu_active_readers))
 			barrier();
 	}
 	/*
@@ -115,54 +125,30 @@ void wait_for_quiescent_state(int parity)
 
 static void switch_qparity(void)
 {
-	int prev_parity;
-
 	/* All threads should read qparity before accessing data structure. */
 	/* Write ptr before changing the qparity */
 	force_mb_all_threads();
-	prev_parity = switch_next_urcu_qparity();
+	debug_yield_write();
+	switch_next_urcu_qparity();
+	debug_yield_write();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
 	 */
-	wait_for_quiescent_state(prev_parity);
+	wait_for_quiescent_state();
 }
 
 void synchronize_rcu(void)
 {
+	debug_yield_write();
 	internal_urcu_lock();
+	debug_yield_write();
 	switch_qparity();
+	debug_yield_write();
 	switch_qparity();
-	internal_urcu_lock();
-}
-
-/*
- * Return old pointer, OK to free, no more reference exist.
- * Called under rcu_write_lock.
- */
-void *urcu_publish_content(void **ptr, void *new)
-{
-	void *oldptr;
-
-	internal_urcu_lock();
-	/*
-	 * We can publish the new pointer before we change the current qparity.
-	 * Readers seeing the new pointer while being in the previous qparity
-	 * window will make us wait until the end of the quiescent state before
-	 * we release the unrelated memory area. However, given we hold the
-	 * urcu_mutex, we are making sure that no further garbage collection can
-	 * occur until we release the mutex, therefore we guarantee that this
-	 * given reader will have completed its execution using the new pointer
-	 * when the next quiescent state window will be over.
-	 */
-	oldptr = *ptr;
-	*ptr = new;
-
-	switch_qparity();
-	switch_qparity();
+	debug_yield_write();
 	internal_urcu_unlock();
-
-	return oldptr;
+	debug_yield_write();
 }
 
 void urcu_add_reader(pthread_t id)
@@ -186,7 +172,7 @@ void urcu_add_reader(pthread_t id)
 	}
 	reader_data[num_readers].tid = id;
 	/* reference to the TLS of _this_ reader thread. */
-	reader_data[num_readers].urcu_active_readers = urcu_active_readers;
+	reader_data[num_readers].urcu_active_readers = &urcu_active_readers;
 	num_readers++;
 }