urcu-bp: use sys_membarrier when available

[urcu.git] / urcu / static / urcu-bp.h

diff --git a/urcu/static/urcu-bp.h b/urcu/static/urcu-bp.h
index df25393d06d6a1a19b0b281f81cedf767bd2d470..182e5feb24f1b5d7022a89a30f342c38821a4211 100644 (file)
--- a/urcu/static/urcu-bp.h
+++ b/urcu/static/urcu-bp.h
@@ -102,6 +102,16 @@ struct rcu_reader {
  */
 extern DECLARE_URCU_TLS(struct rcu_reader *, rcu_reader);
 
+extern int urcu_bp_has_sys_membarrier;
+
+static inline void urcu_bp_smp_mb_slave(void)
+{
+       if (caa_likely(urcu_bp_has_sys_membarrier))
+               cmm_barrier();
+       else
+               cmm_smp_mb();
+}
+
 static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
 {
        unsigned long v;
@@ -131,7 +141,7 @@ static inline void _rcu_read_lock_update(unsigned long tmp)
 {
        if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
                _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp.ctr));
-               cmm_smp_mb();
+               urcu_bp_smp_mb_slave();
        } else
                _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp + RCU_GP_COUNT);
 }
@@ -170,7 +180,7 @@ static inline void _rcu_read_unlock(void)
        tmp = URCU_TLS(rcu_reader)->ctr;
        urcu_assert(tmp & RCU_GP_CTR_NEST_MASK);
        /* Finish using rcu before decrementing the pointer. */
-       cmm_smp_mb();
+       urcu_bp_smp_mb_slave();
        _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp - RCU_GP_COUNT);
        cmm_barrier();  /* Ensure the compiler does not reorder us with mutex */
 }