liburcu-bp: Use membarrier private expedited when available

[urcu.git] / src / urcu.c

diff --git a/src/urcu.c b/src/urcu.c
index ccd9706dda6fe6a8b6bfcba2fced7893054cf3ae..c47f51b53330322468cd5a6b870eab612907fb68 100644 (file)
--- a/src/urcu.c
+++ b/src/urcu.c
@@ -34,6 +34,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <poll.h>
 
 #include "urcu/arch.h"
@@ -71,13 +72,21 @@
 #endif
 
 enum membarrier_cmd {
-       MEMBARRIER_CMD_QUERY = 0,
-       MEMBARRIER_CMD_SHARED = (1 << 0),
+       MEMBARRIER_CMD_QUERY                            = 0,
+       MEMBARRIER_CMD_SHARED                           = (1 << 0),
+       /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
+       /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
+       MEMBARRIER_CMD_PRIVATE_EXPEDITED                = (1 << 3),
+       MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED       = (1 << 4),
 };
 
 #ifdef RCU_MEMBARRIER
 static int init_done;
-int rcu_has_sys_membarrier;
+static int has_sys_membarrier_private_expedited;
+
+#ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
+int rcu_has_sys_membarrier_memb;
+#endif
 
 void __attribute__((constructor)) rcu_init(void);
 #endif
@@ -160,10 +169,14 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 #ifdef RCU_MEMBARRIER
 static void smp_mb_master(void)
 {
-       if (caa_likely(rcu_has_sys_membarrier))
-               (void) membarrier(MEMBARRIER_CMD_SHARED, 0);
-       else
+       if (caa_likely(rcu_has_sys_membarrier_memb)) {
+               if (membarrier(has_sys_membarrier_private_expedited ?
+                               MEMBARRIER_CMD_PRIVATE_EXPEDITED :
+                               MEMBARRIER_CMD_SHARED, 0))
+                       urcu_die(errno);
+       } else {
                cmm_smp_mb();
+       }
 }
 #endif
 
@@ -532,17 +545,50 @@ void rcu_unregister_thread(void)
 }
 
 #ifdef RCU_MEMBARRIER
-void rcu_init(void)
+
+#ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
+static
+void rcu_sys_membarrier_status(bool available)
 {
-       int ret;
+       if (!available)
+               abort();
+}
+#else
+static
+void rcu_sys_membarrier_status(bool available)
+{
+       if (!available)
+               return;
+       rcu_has_sys_membarrier_memb = 1;
+}
+#endif
+
+static
+void rcu_sys_membarrier_init(void)
+{
+       bool available = false;
+       int mask;
+
+       mask = membarrier(MEMBARRIER_CMD_QUERY, 0);
+       if (mask >= 0) {
+               if (mask & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
+                       if (membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0))
+                               urcu_die(errno);
+                       has_sys_membarrier_private_expedited = 1;
+                       available = true;
+               } else if (mask & MEMBARRIER_CMD_SHARED) {
+                       available = true;
+               }
+       }
+       rcu_sys_membarrier_status(available);
+}
 
+void rcu_init(void)
+{
        if (init_done)
                return;
        init_done = 1;
-       ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
-       if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
-               rcu_has_sys_membarrier = 1;
-       }
+       rcu_sys_membarrier_init();
 }
 #endif