From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Sat, 30 Jan 2010 18:28:35 +0000 (-0500)
Subject: URCU: rename light/heavy barriers to slave/master
X-Git-Tag: v0.4.0~1
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=25cc6d18cb2fc9964adf2c1edb53c5539e279382;p=userspace-rcu.git

URCU: rename light/heavy barriers to slave/master

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/urcu-static.h b/urcu-static.h
index 5a75dde..f2c452a 100644
--- a/urcu-static.h
+++ b/urcu-static.h
@@ -160,10 +160,25 @@ static inline void debug_yield_init(void)
 }
 #endif
 
+/*
+ * RCU memory barrier broadcast group. Currently, only broadcast to all process
+ * threads is supported (group 0).
+ *
+ * Slave barriers are only guaranteed to be ordered wrt master barriers.
+ *
+ * The pair ordering is detailed as (O: ordered, X: not ordered) :
+ *               slave  master
+ *        slave    X      O
+ *        master   O      O
+ */
+
+#define MB_GROUP_ALL		0
+#define RCU_MB_GROUP		MB_GROUP_ALL
+
 #ifdef RCU_MEMBARRIER
 extern int has_sys_membarrier;
 
-static inline void smp_mb_light()
+static inline void smp_mb_slave(int group)
 {
 	if (likely(has_sys_membarrier))
 		barrier();
@@ -173,14 +188,14 @@ static inline void smp_mb_light()
 #endif
 
 #ifdef RCU_MB
-static inline void smp_mb_light()
+static inline void smp_mb_slave(int group)
 {
 	smp_mb();
 }
 #endif
 
 #ifdef RCU_SIGNAL
-static inline void smp_mb_light()
+static inline void smp_mb_slave(int group)
 {
 	barrier();
 }
@@ -255,9 +270,9 @@ static inline void _rcu_read_lock(void)
 		_STORE_SHARED(rcu_reader.ctr, _LOAD_SHARED(rcu_gp_ctr));
 		/*
 		 * Set active readers count for outermost nesting level before
-		 * accessing the pointer. See smp_mb_heavy().
+		 * accessing the pointer. See smp_mb_master().
 		 */
-		smp_mb_light();
+		smp_mb_slave(RCU_MB_GROUP);
 	} else {
 		_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT);
 	}
@@ -270,13 +285,13 @@ static inline void _rcu_read_unlock(void)
 	tmp = rcu_reader.ctr;
 	/*
 	 * Finish using rcu before decrementing the pointer.
-	 * See smp_mb_heavy().
+	 * See smp_mb_master().
 	 */
 	if (likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) {
-		smp_mb_light();
+		smp_mb_slave(RCU_MB_GROUP);
 		_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
 		/* write rcu_reader.ctr before read futex */
-		smp_mb_light();
+		smp_mb_slave(RCU_MB_GROUP);
 		wake_up_gp();
 	} else {
 		_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
diff --git a/urcu.c b/urcu.c
index ffdab3c..5e8c612 100644
--- a/urcu.c
+++ b/urcu.c
@@ -121,7 +121,7 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 }
 
 #ifdef RCU_MEMBARRIER
-static void smp_mb_heavy(void)
+static void smp_mb_master(int group)
 {
 	if (likely(has_sys_membarrier))
 		membarrier(MEMBARRIER_EXPEDITED);
@@ -131,7 +131,7 @@ static void smp_mb_heavy(void)
 #endif
 
 #ifdef RCU_MB
-static void smp_mb_heavy(void)
+static void smp_mb_master(int group)
 {
 	smp_mb();
 }
@@ -181,7 +181,7 @@ static void force_mb_all_readers(void)
 	smp_mb();	/* read ->need_mb before ending the barrier */
 }
 
-static void smp_mb_heavy(void)
+static void smp_mb_master(int group)
 {
 	force_mb_all_readers();
 }
@@ -193,7 +193,7 @@ static void smp_mb_heavy(void)
 static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
-	smp_mb_heavy();
+	smp_mb_master(RCU_MB_GROUP);
 	if (uatomic_read(&gp_futex) == -1)
 		futex_async(&gp_futex, FUTEX_WAIT, -1,
 		      NULL, NULL, 0);
@@ -230,7 +230,7 @@ void update_counter_and_wait(void)
 		if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 			uatomic_dec(&gp_futex);
 			/* Write futex before read reader_gp */
-			smp_mb_heavy();
+			smp_mb_master(RCU_MB_GROUP);
 		}
 
 		list_for_each_entry_safe(index, tmp, &registry, head) {
@@ -242,7 +242,7 @@ void update_counter_and_wait(void)
 		if (list_empty(&registry)) {
 			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_heavy();
+				smp_mb_master(RCU_MB_GROUP);
 				uatomic_set(&gp_futex, 0);
 			}
 			break;
@@ -260,7 +260,7 @@ void update_counter_and_wait(void)
 		if (list_empty(&registry)) {
 			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_heavy();
+				smp_mb_master(RCU_MB_GROUP);
 				uatomic_set(&gp_futex, 0);
 			}
 			break;
@@ -270,7 +270,7 @@ void update_counter_and_wait(void)
 				wait_gp();
 				break; /* only escape switch */
 			case KICK_READER_LOOPS:
-				smp_mb_heavy();
+				smp_mb_master(RCU_MB_GROUP);
 				wait_loops = 0;
 				break; /* only escape switch */
 			default:
@@ -294,7 +294,7 @@ void synchronize_rcu(void)
 	 * where new ptr points to. Must be done within rcu_gp_lock because it
 	 * iterates on reader threads.*/
 	/* Write new ptr before changing the qparity */
-	smp_mb_heavy();
+	smp_mb_master(RCU_MB_GROUP);
 
 	/*
 	 * Wait for previous parity to be empty of readers.
@@ -324,7 +324,7 @@ void synchronize_rcu(void)
 	/* Finish waiting for reader threads before letting the old ptr being
 	 * freed. Must be done within rcu_gp_lock because it iterates on reader
 	 * threads. */
-	smp_mb_heavy();
+	smp_mb_master(RCU_MB_GROUP);
 out:
 	mutex_unlock(&rcu_gp_lock);
 }