From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Thu, 12 Feb 2009 04:47:15 +0000 (-0500)
Subject: use smp_*mb()
X-Git-Tag: v0.1~295
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=b715b99eb0d52e0744bfea46c62849f260a5ec58;p=userspace-rcu.git

use smp_*mb()

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

diff --git a/urcu.c b/urcu.c
index 9542b26..162ce00 100644
--- a/urcu.c
+++ b/urcu.c
@@ -43,7 +43,9 @@ unsigned int __thread rand_yield;
 
 static struct reader_data *reader_data;
 static int num_readers, alloc_readers;
+#ifndef DEBUG_FULL_MB
 static int sig_done;
+#endif
 
 void internal_urcu_lock(void)
 {
@@ -77,14 +79,14 @@ static void switch_next_urcu_qparity(void)
 #ifdef DEBUG_FULL_MB
 static void force_mb_all_threads(void)
 {
-	mb();
+	smp_mb();
 }
 #else
 static void force_mb_all_threads(void)
 {
 	struct reader_data *index;
 	/*
-	 * Ask for each threads to execute a mb() so we can consider the
+	 * Ask for each threads to execute a smp_mb() so we can consider the
 	 * compiler barriers around rcu read lock as real memory barriers.
 	 */
 	if (!reader_data)
@@ -92,7 +94,7 @@ static void force_mb_all_threads(void)
 	debug_yield_write();
 	sig_done = 0;
 	debug_yield_write();
-	mb();	/* write sig_done before sending the signals */
+	smp_mb();	/* write sig_done before sending the signals */
 	debug_yield_write();
 	for (index = reader_data; index < reader_data + num_readers; index++) {
 		pthread_kill(index->tid, SIGURCU);
@@ -105,7 +107,7 @@ static void force_mb_all_threads(void)
 	while (sig_done < num_readers)
 		barrier();
 	debug_yield_write();
-	mb();	/* read sig_done before ending the barrier */
+	smp_mb();	/* read sig_done before ending the barrier */
 	debug_yield_write();
 }
 #endif
@@ -147,7 +149,7 @@ void synchronize_rcu(void)
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
 	 */
-	mb();
+	smp_mb();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
@@ -161,7 +163,7 @@ void synchronize_rcu(void)
 	 * the writer waiting forever while new readers are always accessing
 	 * data (no progress).
 	 */
-	mb();
+	smp_mb();
 
 	switch_next_urcu_qparity();	/* 1 -> 0 */
 	debug_yield_write();
@@ -172,7 +174,7 @@ void synchronize_rcu(void)
 	 * waiting forever while new readers are always accessing data (no
 	 * progress).
 	 */
-	mb();
+	smp_mb();
 
 	/*
 	 * Wait for previous parity to be empty of readers.
@@ -256,7 +258,7 @@ void urcu_unregister_thread(void)
 #ifndef DEBUG_FULL_MB
 void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
 {
-	mb();
+	smp_mb();
 	atomic_inc(&sig_done);
 }
 
diff --git a/urcu.h b/urcu.h
index c4a7992..92b31df 100644
--- a/urcu.h
+++ b/urcu.h
@@ -31,6 +31,19 @@
 #define rmb()   asm volatile("lfence":::"memory")
 #define wmb()   asm volatile("sfence" ::: "memory")
 
+/* Assume SMP machine, given we don't have this information */
+#define CONFIG_SMP 1
+
+#ifdef CONFIG_SMP
+#define smp_mb()	mb()
+#define smp_rmb()	rmb()
+#define smp_wmb()	wmb()
+#else
+#define smp_mb()	barrier()
+#define smp_rmb()	barrier()
+#define smp_wmb()	barrier()
+#endif
+
 static inline void atomic_inc(int *v)
 {
 	asm volatile("lock; incl %0"
@@ -173,7 +186,7 @@ static inline void debug_yield_init(void)
 #ifdef DEBUG_FULL_MB
 static inline void read_barrier()
 {
-	mb();
+	smp_mb();
 }
 #else
 static inline void read_barrier()