Add _STORE_SHARED() and _LOAD_SHARED()

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 8cb32a117bb065405ca3f45e0224dfe8fbebbf5d..5e2d2afff5641c57a80548c1f78469c52ccf7b09 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -23,9 +23,14 @@ pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
  * Global grace period counter.
  * Contains the current RCU_GP_CTR_BIT.
  * Also has a RCU_GP_CTR_BIT of 1, to accelerate the reader fast path.
+ * Written to only by writer with mutex taken. Read by both writer and readers.
  */
 long urcu_gp_ctr = RCU_GP_COUNT;
 
+/*
+ * Written to only by each individual reader. Read by both the reader and the
+ * writers.
+ */
 long __thread urcu_active_readers;
 
 /* Thread IDs of registered readers */
@@ -73,7 +78,7 @@ void internal_urcu_unlock(void)
  */
 static void switch_next_urcu_qparity(void)
 {
-       urcu_gp_ctr ^= RCU_GP_CTR_BIT;
+       STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR_BIT);
 }
 
 #ifdef DEBUG_FULL_MB
@@ -183,8 +188,8 @@ void synchronize_rcu(void)
         * 0 quiescent state. Failure to do so could result in the writer
         * waiting forever while new readers are always accessing data (no
         * progress).
+        * Ensured by STORE_SHARED and LOAD_SHARED.
         */
-       smp_mc();
 
        /*
         * Wait for previous parity to be empty of readers.
@@ -196,8 +201,8 @@ void synchronize_rcu(void)
         * committing qparity update to memory. Failure to do so could result in
         * the writer waiting forever while new readers are always accessing
         * data (no progress).
+        * Ensured by STORE_SHARED and LOAD_SHARED.
         */
-       smp_mc();
 
        switch_next_urcu_qparity();     /* 1 -> 0 */
 
@@ -206,8 +211,8 @@ void synchronize_rcu(void)
         * 1 quiescent state. Failure to do so could result in the writer
         * waiting forever while new readers are always accessing data (no
         * progress).
+        * Ensured by STORE_SHARED and LOAD_SHARED.
         */
-       smp_mc();
 
        /*
         * Wait for previous parity to be empty of readers.