From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Wed, 13 Jan 2010 16:59:00 +0000 (-0500)
Subject: urcu signal-based renames
X-Git-Tag: v0.4.0~10
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=9d7e3f89772f08cca26d727f47d44ecd47c94401;p=userspace-rcu.git

urcu signal-based renames

reader_barrier renamed to smp_mb_light
force_mb_all_readers renamed to smp_mb_heavy

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

diff --git a/urcu-static.h b/urcu-static.h
index 0708df7..d466131 100644
--- a/urcu-static.h
+++ b/urcu-static.h
@@ -136,12 +136,12 @@ static inline void debug_yield_init(void)
 #endif
 
 #ifdef RCU_MB
-static inline void reader_barrier()
+static inline void smp_mb_light()
 {
 	smp_mb();
 }
 #else
-static inline void reader_barrier()
+static inline void smp_mb_light()
 {
 	barrier();
 }
@@ -216,9 +216,9 @@ 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 force_mb_all_readers().
+		 * accessing the pointer. See smp_mb_heavy().
 		 */
-		reader_barrier();
+		smp_mb_light();
 	} else {
 		_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT);
 	}
@@ -231,13 +231,13 @@ static inline void _rcu_read_unlock(void)
 	tmp = rcu_reader.ctr;
 	/*
 	 * Finish using rcu before decrementing the pointer.
-	 * See force_mb_all_readers().
+	 * See smp_mb_heavy().
 	 */
 	if (likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) {
-		reader_barrier();
+		smp_mb_light();
 		_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
 		/* write rcu_reader.ctr before read futex */
-		reader_barrier();
+		smp_mb_light();
 		wake_up_gp();
 	} else {
 		_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
diff --git a/urcu.c b/urcu.c
index 3132e59..53dfbd5 100644
--- a/urcu.c
+++ b/urcu.c
@@ -119,43 +119,11 @@ static void switch_next_rcu_qparity(void)
 }
 
 #ifdef RCU_MB
-#if 0 /* unused */
-static void force_mb_single_thread(struct rcu_reader *index)
+static void smp_mb_heavy()
 {
 	smp_mb();
 }
-#endif //0
-
-static void force_mb_all_readers(void)
-{
-	smp_mb();
-}
-#else /* #ifdef RCU_MB */
-#if 0 /* unused */
-static void force_mb_single_thread(struct rcu_reader *index)
-{
-	assert(!list_empty(&registry));
-	/*
-	 * pthread_kill has a smp_mb(). But beware, we assume it performs
-	 * a cache flush on architectures with non-coherent cache. Let's play
-	 * safe and don't assume anything : we use smp_mc() to make sure the
-	 * cache flush is enforced.
-	 */
-	index->need_mb = 1;
-	smp_mc();	/* write ->need_mb before sending the signals */
-	pthread_kill(index->tid, SIGRCU);
-	smp_mb();
-	/*
-	 * Wait for sighandler (and thus mb()) to execute on every thread.
-	 * BUSY-LOOP.
-	 */
-	while (index->need_mb) {
-		poll(NULL, 0, 1);
-	}
-	smp_mb();	/* read ->need_mb before ending the barrier */
-}
-#endif //0
-
+#else
 static void force_mb_all_readers(void)
 {
 	struct rcu_reader *index;
@@ -198,6 +166,11 @@ static void force_mb_all_readers(void)
 	}
 	smp_mb();	/* read ->need_mb before ending the barrier */
 }
+
+static void smp_mb_heavy()
+{
+	force_mb_all_readers();
+}
 #endif /* #else #ifdef RCU_MB */
 
 /*
@@ -206,7 +179,7 @@ static void force_mb_all_readers(void)
 static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
-	force_mb_all_readers();
+	smp_mb_heavy();
 	if (uatomic_read(&gp_futex) == -1)
 		futex_async(&gp_futex, FUTEX_WAIT, -1,
 		      NULL, NULL, 0);
@@ -228,7 +201,7 @@ void wait_for_quiescent_state(void)
 		if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 			uatomic_dec(&gp_futex);
 			/* Write futex before read reader_gp */
-			force_mb_all_readers();
+			smp_mb_heavy();
 		}
 
 		list_for_each_entry_safe(index, tmp, &registry, head) {
@@ -240,7 +213,7 @@ void wait_for_quiescent_state(void)
 		if (list_empty(&registry)) {
 			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				force_mb_all_readers();
+				smp_mb_heavy();
 				uatomic_set(&gp_futex, 0);
 			}
 			break;
@@ -258,7 +231,7 @@ void wait_for_quiescent_state(void)
 		if (list_empty(&registry)) {
 			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				force_mb_all_readers();
+				smp_mb_heavy();
 				uatomic_set(&gp_futex, 0);
 			}
 			break;
@@ -268,7 +241,7 @@ void wait_for_quiescent_state(void)
 				wait_gp();
 				break; /* only escape switch */
 			case KICK_READER_LOOPS:
-				force_mb_all_readers();
+				smp_mb_heavy();
 				wait_loops = 0;
 				break; /* only escape switch */
 			default:
@@ -289,7 +262,7 @@ void synchronize_rcu(void)
 	 * where new ptr points to. Must be done within internal_rcu_lock
 	 * because it iterates on reader threads.*/
 	/* Write new ptr before changing the qparity */
-	force_mb_all_readers();
+	smp_mb_heavy();
 
 	switch_next_rcu_qparity();	/* 0 -> 1 */
 
@@ -353,7 +326,7 @@ void synchronize_rcu(void)
 	/* Finish waiting for reader threads before letting the old ptr being
 	 * freed. Must be done within internal_rcu_lock because it iterates on
 	 * reader threads. */
-	force_mb_all_readers();
+	smp_mb_heavy();
 
 	internal_rcu_unlock();
 }