rename internal_rcu_lock() into mutex_lock/unlock(&rcu_gp_lock)

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 53dfbd5286e4ea5a02044fe23a17425fe738cc4f..6e9589145cf789a06c00aa988cb01d8c3dcb27fa 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -23,6 +23,7 @@
  * IBM's contributions to this file may be relicensed under LGPLv2 or later.
  */
 
+#define _BSD_SOURCE
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
@@ -36,18 +37,27 @@
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #include "urcu.h"
 
-#ifndef RCU_MB
+#ifdef RCU_MEMBARRIER
 static int init_done;
+int has_sys_membarrier;
 
 void __attribute__((constructor)) rcu_init(void);
-void __attribute__((destructor)) rcu_exit(void);
-#else
+#endif
+
+#ifdef RCU_MB
 void rcu_init(void)
 {
 }
 #endif
 
-static pthread_mutex_t rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
+#ifdef RCU_SIGNAL
+static int init_done;
+
+void __attribute__((constructor)) rcu_init(void);
+void __attribute__((destructor)) rcu_exit(void);
+#endif
+
+static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
 
 int gp_futex;
 
@@ -72,18 +82,18 @@ unsigned int __thread rand_yield;
 
 static LIST_HEAD(registry);
 
-static void internal_rcu_lock(void)
+static void mutex_lock(pthread_mutex_t *mutex)
 {
        int ret;
 
 #ifndef DISTRUST_SIGNALS_EXTREME
-       ret = pthread_mutex_lock(&rcu_mutex);
+       ret = pthread_mutex_lock(mutex);
        if (ret) {
                perror("Error in pthread mutex lock");
                exit(-1);
        }
 #else /* #ifndef DISTRUST_SIGNALS_EXTREME */
-       while ((ret = pthread_mutex_trylock(&rcu_mutex)) != 0) {
+       while ((ret = pthread_mutex_trylock(mutex)) != 0) {
                if (ret != EBUSY && ret != EINTR) {
                        printf("ret = %d, errno = %d\n", ret, errno);
                        perror("Error in pthread mutex lock");
@@ -99,11 +109,11 @@ static void internal_rcu_lock(void)
 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
 }
 
-static void internal_rcu_unlock(void)
+static void mutex_unlock(pthread_mutex_t *mutex)
 {
        int ret;
 
-       ret = pthread_mutex_unlock(&rcu_mutex);
+       ret = pthread_mutex_unlock(mutex);
        if (ret) {
                perror("Error in pthread mutex unlock");
                exit(-1);
@@ -111,19 +121,31 @@ static void internal_rcu_unlock(void)
 }
 
 /*
- * called with rcu_mutex held.
+ * called with rcu_gp_lock held.
  */
 static void switch_next_rcu_qparity(void)
 {
        STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
 }
 
+#ifdef RCU_MEMBARRIER
+static void smp_mb_heavy(void)
+{
+       if (likely(has_sys_membarrier))
+               membarrier(MEMBARRIER_EXPEDITED);
+       else
+               smp_mb();
+}
+#endif
+
 #ifdef RCU_MB
-static void smp_mb_heavy()
+static void smp_mb_heavy(void)
 {
        smp_mb();
 }
-#else
+#endif
+
+#ifdef RCU_SIGNAL
 static void force_mb_all_readers(void)
 {
        struct rcu_reader *index;
@@ -167,11 +189,11 @@ static void force_mb_all_readers(void)
        smp_mb();       /* read ->need_mb before ending the barrier */
 }
 
-static void smp_mb_heavy()
+static void smp_mb_heavy(void)
 {
        force_mb_all_readers();
 }
-#endif /* #else #ifdef RCU_MB */
+#endif /* #ifdef RCU_SIGNAL */
 
 /*
  * synchronize_rcu() waiting. Single thread.
@@ -256,11 +278,11 @@ void wait_for_quiescent_state(void)
 
 void synchronize_rcu(void)
 {
-       internal_rcu_lock();
+       mutex_lock(&rcu_gp_lock);
 
        /* All threads should read qparity before accessing data structure
-        * where new ptr points to. Must be done within internal_rcu_lock
-        * because it iterates on reader threads.*/
+        * where new ptr points to. Must be done within rcu_gp_lock because it
+        * iterates on reader threads.*/
        /* Write new ptr before changing the qparity */
        smp_mb_heavy();
 
@@ -324,11 +346,11 @@ void synchronize_rcu(void)
        wait_for_quiescent_state();     /* Wait readers in parity 1 */
 
        /* Finish waiting for reader threads before letting the old ptr being
-        * freed. Must be done within internal_rcu_lock because it iterates on
-        * reader threads. */
+        * freed. Must be done within rcu_gp_lock because it iterates on reader
+        * threads. */
        smp_mb_heavy();
 
-       internal_rcu_unlock();
+       mutex_unlock(&rcu_gp_lock);
 }
 
 /*
@@ -351,20 +373,31 @@ void rcu_register_thread(void)
        assert(rcu_reader.need_mb == 0);
        assert(rcu_reader.ctr == 0);
 
-       internal_rcu_lock();
+       mutex_lock(&rcu_gp_lock);
        rcu_init();     /* In case gcc does not support constructor attribute */
        list_add(&rcu_reader.head, &registry);
-       internal_rcu_unlock();
+       mutex_unlock(&rcu_gp_lock);
 }
 
 void rcu_unregister_thread(void)
 {
-       internal_rcu_lock();
+       mutex_lock(&rcu_gp_lock);
        list_del(&rcu_reader.head);
-       internal_rcu_unlock();
+       mutex_unlock(&rcu_gp_lock);
+}
+
+#ifdef RCU_MEMBARRIER
+void rcu_init(void)
+{
+       if (init_done)
+               return;
+       init_done = 1;
+       if (!membarrier(MEMBARRIER_EXPEDITED | MEMBARRIER_QUERY))
+               has_sys_membarrier = 1;
 }
+#endif
 
-#ifndef RCU_MB
+#ifdef RCU_SIGNAL
 static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
 {
        /*
@@ -381,9 +414,9 @@ static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
  * rcu_init constructor. Called when the library is linked, but also when
  * reader threads are calling rcu_register_thread().
  * Should only be called by a single thread at a given time. This is ensured by
- * holing the internal_rcu_lock() from rcu_register_thread() or by running at
- * library load time, which should not be executed by multiple threads nor
- * concurrently with rcu_register_thread() anyway.
+ * holing the rcu_gp_lock from rcu_register_thread() or by running at library
+ * load time, which should not be executed by multiple threads nor concurrently
+ * with rcu_register_thread() anyway.
  */
 void rcu_init(void)
 {
@@ -417,4 +450,4 @@ void rcu_exit(void)
        assert(act.sa_sigaction == sigrcu_handler);
        assert(list_empty(&registry));
 }
-#endif /* #ifndef RCU_MB */
+#endif /* #ifdef RCU_SIGNAL */