X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=918d2742a0429683c11e42c60c77187bc908e862;hp=140cd19b98add54f276755e08b13bfad9e8c3d0c;hb=eaf2c3f4b9041d2a6a85d7f9e56f6014603367d4;hpb=27d65bc5db18f8563a9120924569acffb845ec4d

diff --git a/urcu.c b/urcu.c
index 140cd19..918d274 100644
--- a/urcu.c
+++ b/urcu.c
@@ -3,7 +3,7 @@
  *
  * Userspace RCU library
  *
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
  *
  * This library is free software; you can redistribute it and/or
@@ -99,9 +99,9 @@ static void mutex_lock(pthread_mutex_t *mutex)
 			perror("Error in pthread mutex lock");
 			exit(-1);
 		}
-		if (rcu_reader.need_mb) {
+		if (LOAD_SHARED(rcu_reader.need_mb)) {
 			smp_mb();
-			rcu_reader.need_mb = 0;
+			_STORE_SHARED(rcu_reader.need_mb, 0);
 			smp_mb();
 		}
 		poll(NULL,0,10);
@@ -154,9 +154,8 @@ static void force_mb_all_readers(void)
 	 * safe and don't assume anything : we use smp_mc() to make sure the
 	 * cache flush is enforced.
 	 */
-	list_for_each_entry(index, &registry, head) {
-		index->need_mb = 1;
-		smp_mc();	/* write need_mb before sending the signal */
+	list_for_each_entry(index, &registry, node) {
+		STORE_SHARED(index->need_mb, 1);
 		pthread_kill(index->tid, SIGRCU);
 	}
 	/*
@@ -172,8 +171,8 @@ static void force_mb_all_readers(void)
 	 * relevant bug report.  For Linux kernels, we recommend getting
 	 * the Linux Test Project (LTP).
 	 */
-	list_for_each_entry(index, &registry, head) {
-		while (index->need_mb) {
+	list_for_each_entry(index, &registry, node) {
+		while (LOAD_SHARED(index->need_mb)) {
 			pthread_kill(index->tid, SIGRCU);
 			poll(NULL, 0, 1);
 		}
@@ -209,13 +208,15 @@ void update_counter_and_wait(void)
 	STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
 
 	/*
-	 * Must commit qparity update to memory before waiting for other parity
-	 * quiescent state. Failure to do so could result in the writer waiting
-	 * forever while new readers are always accessing data (no progress).
-	 * Ensured by STORE_SHARED and LOAD_SHARED.
+	 * Must commit rcu_gp_ctr update to memory before waiting for quiescent
+	 * state. Failure to do so could result in the writer waiting forever
+	 * while new readers are always accessing data (no progress). Enforce
+	 * compiler-order of store to rcu_gp_ctr before load rcu_reader ctr.
 	 */
+	barrier();
 
 	/*
+	 *
 	 * Adding a smp_mb() which is _not_ formally required, but makes the
 	 * model easier to understand. It does not have a big performance impact
 	 * anyway, given this is the write-side.
@@ -233,9 +234,9 @@ void update_counter_and_wait(void)
 			smp_mb_master(RCU_MB_GROUP);
 		}
 
-		list_for_each_entry_safe(index, tmp, &registry, head) {
-			if (!rcu_old_gp_ongoing(&index->ctr))
-				list_move(&index->head, &qsreaders);
+		list_for_each_entry_safe(index, tmp, &registry, node) {
+			if (!rcu_gp_ongoing(&index->ctr))
+				list_move(&index->node, &qsreaders);
 		}
 
 #ifndef HAS_INCOHERENT_CACHES
@@ -303,11 +304,12 @@ void synchronize_rcu(void)
 
 	/*
 	 * Must finish waiting for quiescent state for parity 0 before
-	 * committing qparity update to memory. Failure to do so could result in
-	 * the writer waiting forever while new readers are always accessing
-	 * data (no progress).
-	 * Ensured by STORE_SHARED and LOAD_SHARED.
+	 * committing next rcu_gp_ctr update to memory. Failure to do so could
+	 * result in the writer waiting forever while new readers are always
+	 * accessing data (no progress).  Enforce compiler-order of load
+	 * rcu_reader ctr before store to rcu_gp_ctr.
 	 */
+	barrier();
 
 	/*
 	 * Adding a smp_mb() which is _not_ formally required, but makes the
@@ -347,18 +349,18 @@ void rcu_register_thread(void)
 {
 	rcu_reader.tid = pthread_self();
 	assert(rcu_reader.need_mb == 0);
-	assert(rcu_reader.ctr == 0);
+	assert(!(rcu_reader.ctr & RCU_GP_CTR_NEST_MASK));
 
 	mutex_lock(&rcu_gp_lock);
 	rcu_init();	/* In case gcc does not support constructor attribute */
-	list_add(&rcu_reader.head, &registry);
+	list_add(&rcu_reader.node, &registry);
 	mutex_unlock(&rcu_gp_lock);
 }
 
 void rcu_unregister_thread(void)
 {
 	mutex_lock(&rcu_gp_lock);
-	list_del(&rcu_reader.head);
+	list_del(&rcu_reader.node);
 	mutex_unlock(&rcu_gp_lock);
 }
 
@@ -382,7 +384,7 @@ static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
 	 * executed on.
 	 */
 	smp_mb();
-	rcu_reader.need_mb = 0;
+	_STORE_SHARED(rcu_reader.need_mb, 0);
 	smp_mb();
 }