Update list, rculist and hlist

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 51c279f3aa91e7731ce4016f88af4fa7cd7d0025..b323711294ae25ffc7c65641ab1a73240aa03aaa 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -36,23 +36,25 @@
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #include "urcu.h"
 
-#ifndef DEBUG_FULL_MB
+#ifndef URCU_MB
+static int init_done;
+
 void __attribute__((constructor)) urcu_init(void);
 void __attribute__((destructor)) urcu_exit(void);
 #else
-static inline void urcu_init(void)
+void urcu_init(void)
 {
 }
 #endif
 
-int init_done;
+static pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
+int gp_futex;
 
 /*
  * 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.
+ * Also has a RCU_GP_COUNT 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;
@@ -81,7 +83,7 @@ static struct reader_registry *registry;
 static char __thread need_mb;
 static int num_readers, alloc_readers;
 
-void internal_urcu_lock(void)
+static void internal_urcu_lock(void)
 {
        int ret;
 
@@ -108,7 +110,7 @@ void internal_urcu_lock(void)
 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
 }
 
-void internal_urcu_unlock(void)
+static void internal_urcu_unlock(void)
 {
        int ret;
 
@@ -127,20 +129,17 @@ static void switch_next_urcu_qparity(void)
        STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR_BIT);
 }
 
-#ifdef DEBUG_FULL_MB
-#ifdef HAS_INCOHERENT_CACHES
+#ifdef URCU_MB
 static void force_mb_single_thread(struct reader_registry *index)
 {
        smp_mb();
 }
-#endif /* #ifdef HAS_INCOHERENT_CACHES */
 
 static void force_mb_all_threads(void)
 {
        smp_mb();
 }
-#else /* #ifdef DEBUG_FULL_MB */
-#ifdef HAS_INCOHERENT_CACHES
+#else /* #ifdef URCU_MB */
 static void force_mb_single_thread(struct reader_registry *index)
 {
        assert(registry);
@@ -163,7 +162,6 @@ static void force_mb_single_thread(struct reader_registry *index)
        }
        smp_mb();       /* read ->need_mb before ending the barrier */
 }
-#endif /* #ifdef HAS_INCOHERENT_CACHES */
 
 static void force_mb_all_threads(void)
 {
@@ -206,7 +204,28 @@ static void force_mb_all_threads(void)
        }
        smp_mb();       /* read ->need_mb before ending the barrier */
 }
-#endif /* #else #ifdef DEBUG_FULL_MB */
+#endif /* #else #ifdef URCU_MB */
+
+/*
+ * synchronize_rcu() waiting. Single thread.
+ */
+static void wait_gp(struct reader_registry *index)
+{
+       uatomic_dec(&gp_futex);
+       force_mb_single_thread(index); /* Write futex before read reader_gp */
+       if (!rcu_old_gp_ongoing(index->urcu_active_readers)) {
+               /* Read reader_gp before write futex */
+               force_mb_single_thread(index);
+               /* Callbacks are queued, don't wait. */
+               uatomic_set(&gp_futex, 0);
+       } else {
+               /* Read reader_gp before read futex */
+               force_mb_single_thread(index);
+               if (uatomic_read(&gp_futex) == -1)
+                       futex(&gp_futex, FUTEX_WAIT, -1,
+                             NULL, NULL, 0);
+       }
+}
 
 void wait_for_quiescent_state(void)
 {
@@ -218,20 +237,30 @@ void wait_for_quiescent_state(void)
         * Wait for each thread urcu_active_readers count to become 0.
         */
        for (index = registry; index < registry + num_readers; index++) {
+               int wait_loops = 0;
 #ifndef HAS_INCOHERENT_CACHES
-               while (rcu_old_gp_ongoing(index->urcu_active_readers))
-                       cpu_relax();
+               while (rcu_old_gp_ongoing(index->urcu_active_readers)) {
+                       if (wait_loops++ == RCU_QS_ACTIVE_ATTEMPTS) {
+                               wait_gp(index);
+                       } else {
+                               cpu_relax();
+                       }
+               }
 #else /* #ifndef HAS_INCOHERENT_CACHES */
-               int wait_loops = 0;
                /*
                 * BUSY-LOOP. Force the reader thread to commit its
                 * urcu_active_readers update to memory if we wait for too long.
                 */
                while (rcu_old_gp_ongoing(index->urcu_active_readers)) {
-                       if (wait_loops++ == KICK_READER_LOOPS) {
+                       switch (wait_loops++) {
+                       case RCU_QS_ACTIVE_ATTEMPTS:
+                               wait_gp(index);
+                               break;
+                       case KICK_READER_LOOPS:
                                force_mb_single_thread(index);
                                wait_loops = 0;
-                       } else {
+                               break;
+                       default:
                                cpu_relax();
                        }
                }
@@ -344,7 +373,13 @@ void *rcu_assign_pointer_sym(void **p, void *v)
 void *rcu_xchg_pointer_sym(void **p, void *v)
 {
        wmb();
-       return xchg(p, v);
+       return uatomic_xchg(p, v);
+}
+
+void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new)
+{
+       wmb();
+       return uatomic_cmpxchg(p, old, _new);
 }
 
 void *rcu_publish_content_sym(void **p, void *v)
@@ -420,7 +455,7 @@ void rcu_unregister_thread(void)
        internal_urcu_unlock();
 }
 
-#ifndef DEBUG_FULL_MB
+#ifndef URCU_MB
 static void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
 {
        /*
@@ -473,4 +508,4 @@ void urcu_exit(void)
        assert(act.sa_sigaction == sigurcu_handler);
        free(registry);
 }
-#endif /* #ifndef DEBUG_FULL_MB */
+#endif /* #ifndef URCU_MB */