qsbr: save two full smp_mb() when the writer is also a reader.

[urcu.git] / urcu-qsbr.c

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index e077eac8f2b4b4bc7c44cadaf0f96d012be60fe3..3f21be3160731979b6f39455b1202ccf00849237 100644 (file)
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -106,11 +106,6 @@ static void force_mb_single_thread(struct reader_registry *index)
 }
 #endif /* #ifdef HAS_INCOHERENT_CACHES */
 
-static void force_mb_all_threads(void)
-{
-       smp_mb();
-}
-
 static void wait_for_quiescent_state(void)
 {
        struct reader_registry *index;
@@ -153,18 +148,18 @@ void synchronize_rcu(void)
         * our own quiescent state. This allows using synchronize_rcu() in
         * threads registered as readers.
         */
+       smp_mb();
        if (was_online)
-               _rcu_thread_offline();
+               STORE_SHARED(rcu_reader_qs_gp, 0);
 
        internal_urcu_lock();
-       force_mb_all_threads();
        STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr + 2);
        wait_for_quiescent_state();
-       force_mb_all_threads();
        internal_urcu_unlock();
 
        if (was_online)
-               _rcu_thread_online();
+               _STORE_SHARED(rcu_reader_qs_gp, LOAD_SHARED(urcu_gp_ctr) + 1);
+       smp_mb();
 }
 
 /*