From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 18 Sep 2015 20:33:29 +0000 (-0400)
Subject: Cleanup: urcu: remove unused membarrier "group" parameter
X-Git-Tag: v0.9.0~35
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=a4922ed92bea8e5552a3e66b7dd7b4721b754c90;p=userspace-rcu.git

Cleanup: urcu: remove unused membarrier "group" parameter

Was planned in the 2010 implementation, but has never been used, and is
not needed with the current kernel membarrier implementation.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/urcu.c b/urcu.c
index 4702ba9..1aa00fe 100644
--- a/urcu.c
+++ b/urcu.c
@@ -165,7 +165,7 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 }
 
 #ifdef RCU_MEMBARRIER
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	if (caa_likely(rcu_has_sys_membarrier))
 		(void) membarrier(MEMBARRIER_CMD_SHARED, 0);
@@ -175,7 +175,7 @@ static void smp_mb_master(int group)
 #endif
 
 #ifdef RCU_MB
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	cmm_smp_mb();
 }
@@ -224,7 +224,7 @@ static void force_mb_all_readers(void)
 	cmm_smp_mb();	/* read ->need_mb before ending the barrier */
 }
 
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	force_mb_all_readers();
 }
@@ -236,7 +236,7 @@ static void smp_mb_master(int group)
 static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
-	smp_mb_master(RCU_MB_GROUP);
+	smp_mb_master();
 	if (uatomic_read(&rcu_gp.futex) != -1)
 		return;
 	while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
@@ -280,7 +280,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 			uatomic_dec(&rcu_gp.futex);
 			/* Write futex before read reader_gp */
-			smp_mb_master(RCU_MB_GROUP);
+			smp_mb_master();
 		}
 
 		cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
@@ -310,7 +310,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (cds_list_empty(input_readers)) {
 			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				uatomic_set(&rcu_gp.futex, 0);
 			}
 			break;
@@ -333,13 +333,13 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (cds_list_empty(input_readers)) {
 			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				uatomic_set(&rcu_gp.futex, 0);
 			}
 			break;
 		} else {
 			if (wait_gp_loops == KICK_READER_LOOPS) {
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				wait_gp_loops = 0;
 			}
 			/* Temporarily unlock the registry lock. */
@@ -400,7 +400,7 @@ void synchronize_rcu(void)
 	 * because it iterates on reader threads.
 	 */
 	/* Write new ptr before changing the qparity */
-	smp_mb_master(RCU_MB_GROUP);
+	smp_mb_master();
 
 	/*
 	 * Wait for readers to observe original parity or be quiescent.
@@ -461,7 +461,7 @@ void synchronize_rcu(void)
 	 * being freed. Must be done within rcu_registry_lock because it
 	 * iterates on reader threads.
 	 */
-	smp_mb_master(RCU_MB_GROUP);
+	smp_mb_master();
 out:
 	mutex_unlock(&rcu_registry_lock);
 	mutex_unlock(&rcu_gp_lock);
diff --git a/urcu/static/urcu.h b/urcu/static/urcu.h
index 3fb457b..92185d7 100644
--- a/urcu/static/urcu.h
+++ b/urcu/static/urcu.h
@@ -81,9 +81,6 @@ enum rcu_state {
 };
 
 /*
- * 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) :
@@ -92,13 +89,10 @@ enum rcu_state {
  *        master   O      O
  */
 
-#define MB_GROUP_ALL		0
-#define RCU_MB_GROUP		MB_GROUP_ALL
-
 #ifdef RCU_MEMBARRIER
 extern int rcu_has_sys_membarrier;
 
-static inline void smp_mb_slave(int group)
+static inline void smp_mb_slave(void)
 {
 	if (caa_likely(rcu_has_sys_membarrier))
 		cmm_barrier();
@@ -108,14 +102,14 @@ static inline void smp_mb_slave(int group)
 #endif
 
 #ifdef RCU_MB
-static inline void smp_mb_slave(int group)
+static inline void smp_mb_slave(void)
 {
 	cmm_smp_mb();
 }
 #endif
 
 #ifdef RCU_SIGNAL
-static inline void smp_mb_slave(int group)
+static inline void smp_mb_slave(void)
 {
 	cmm_barrier();
 }
@@ -202,7 +196,7 @@ static inline void _rcu_read_lock_update(unsigned long tmp)
 {
 	if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
 		_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp.ctr));
-		smp_mb_slave(RCU_MB_GROUP);
+		smp_mb_slave();
 	} else
 		_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT);
 }
@@ -239,9 +233,9 @@ static inline void _rcu_read_lock(void)
 static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp)
 {
 	if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) {
-		smp_mb_slave(RCU_MB_GROUP);
+		smp_mb_slave();
 		_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT);
-		smp_mb_slave(RCU_MB_GROUP);
+		smp_mb_slave();
 		wake_up_gp();
 	} else
 		_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT);