X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=urcu-static.h;h=44bcd073710e3e98d760c667eb7aa787238bb3ff;hb=f0708810fe66d7fdcf52903c607ed65c9fa664c7;hp=bd11be8d212fbd942d42ba00fd33711347b04c39;hpb=02be55611d3b1c7bf4fdfcb3a9c98f621882d417;p=userspace-rcu.git

diff --git a/urcu-static.h b/urcu-static.h
index bd11be8..44bcd07 100644
--- a/urcu-static.h
+++ b/urcu-static.h
@@ -45,6 +45,26 @@
 extern "C" {
 #endif 
 
+/* Default is RCU_MEMBARRIER */
+#if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL)
+#define RCU_MEMBARRIER
+#endif
+
+#ifdef RCU_MEMBARRIER
+#include <unistd.h>
+#include <sys/syscall.h>
+
+/* If the headers do not support SYS_membarrier, statically use RCU_MB */
+#ifdef SYS_membarrier
+# define MEMBARRIER_EXPEDITED            (1 << 0)
+# define MEMBARRIER_DELAYED              (1 << 1)
+# define membarrier(...)		syscall(__NR_membarrier, __VA_ARGS__)
+#else
+# undef RCU_MEMBARRIER
+# define RCU_MB
+#endif
+#endif
+
 /*
  * This code section can only be included in LGPL 2.1 compatible source code.
  * See below for the function call wrappers which can be used in code meant to
@@ -89,14 +109,13 @@ extern "C" {
 #define YIELD_WRITE	(1 << 1)
 
 /*
- * Updates without RCU_MB are much slower. Account this in
- * the delay.
+ * Updates with RCU_SIGNAL are much slower. Account this in the delay.
  */
-#ifdef RCU_MB
+#ifdef RCU_SIGNAL
 /* maximum sleep delay, in us */
-#define MAX_SLEEP 50
-#else
 #define MAX_SLEEP 30000
+#else
+#define MAX_SLEEP 50
 #endif
 
 extern unsigned int yield_active;
@@ -135,13 +154,27 @@ static inline void debug_yield_init(void)
 }
 #endif
 
+#ifdef RCU_MEMBARRIER
+extern int has_sys_membarrier;
+
+static inline void smp_mb_light()
+{
+	if (likely(has_sys_membarrier))
+		barrier();
+	else
+		smp_mb();
+}
+#endif
+
 #ifdef RCU_MB
-static inline void reader_barrier()
+static inline void smp_mb_light()
 {
 	smp_mb();
 }
-#else
-static inline void reader_barrier()
+#endif
+
+#ifdef RCU_SIGNAL
+static inline void smp_mb_light()
 {
 	barrier();
 }
@@ -216,9 +249,9 @@ 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_threads().
+		 * accessing the pointer. See smp_mb_heavy().
 		 */
-		reader_barrier();
+		smp_mb_light();
 	} else {
 		_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT);
 	}
@@ -231,13 +264,13 @@ static inline void _rcu_read_unlock(void)
 	tmp = rcu_reader.ctr;
 	/*
 	 * Finish using rcu before decrementing the pointer.
-	 * See force_mb_all_threads().
+	 * 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);