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(...) 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
#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;
}
#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();
}
_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);
}
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);