/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
#include "urcu.h"
-pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
+#ifndef URCU_MB
+void __attribute__((constructor)) urcu_init(void);
+void __attribute__((destructor)) urcu_exit(void);
+#else
+void urcu_init(void)
+{
+}
+#endif
+
+static int init_done;
+
+static 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.
+ * 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;
static char __thread need_mb;
static int num_readers, alloc_readers;
-void internal_urcu_lock(void)
+static void internal_urcu_lock(void)
{
int ret;
#endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
}
-void internal_urcu_unlock(void)
+static void internal_urcu_unlock(void)
{
int ret;
STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR_BIT);
}
-#ifdef DEBUG_FULL_MB
+#ifdef URCU_MB
#ifdef HAS_INCOHERENT_CACHES
static void force_mb_single_thread(struct reader_registry *index)
{
{
smp_mb();
}
-#else /* #ifdef DEBUG_FULL_MB */
+#else /* #ifdef URCU_MB */
#ifdef HAS_INCOHERENT_CACHES
static void force_mb_single_thread(struct reader_registry *index)
{
}
smp_mb(); /* read ->need_mb before ending the barrier */
}
-#endif /* #else #ifdef DEBUG_FULL_MB */
+#endif /* #else #ifdef URCU_MB */
void wait_for_quiescent_state(void)
{
*/
/*
- * Current RCU formal verification model assumes sequential execution of
- * the write-side. Add core synchronization instructions. Can be removed
- * if the formal model is extended to prove that reordering is still
- * correct.
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
*/
- sync_core(); /* Formal model assumes serialized execution */
+ smp_mb();
/*
* Wait for previous parity to be empty of readers.
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
- sync_core(); /* Formal model assumes serialized execution */
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
switch_next_urcu_qparity(); /* 1 -> 0 */
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
- sync_core(); /* Formal model assumes serialized execution */
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
/*
* Wait for previous parity to be empty of readers.
void rcu_register_thread(void)
{
internal_urcu_lock();
+ urcu_init(); /* In case gcc does not support constructor attribute */
rcu_add_reader(pthread_self());
internal_urcu_unlock();
}
internal_urcu_unlock();
}
-#ifndef DEBUG_FULL_MB
+#ifndef URCU_MB
static void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
{
/*
smp_mb();
}
-void __attribute__((constructor)) urcu_init(void)
+/*
+ * urcu_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_urcu_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 urcu_init(void)
{
struct sigaction act;
int ret;
+ if (init_done)
+ return;
+ init_done = 1;
+
act.sa_sigaction = sigurcu_handler;
+ act.sa_flags = SA_SIGINFO | SA_RESTART;
+ sigemptyset(&act.sa_mask);
ret = sigaction(SIGURCU, &act, NULL);
if (ret) {
perror("Error in sigaction");
}
}
-void __attribute__((destructor)) urcu_exit(void)
+void urcu_exit(void)
{
struct sigaction act;
int ret;
assert(act.sa_sigaction == sigurcu_handler);
free(registry);
}
-#endif /* #ifndef DEBUG_FULL_MB */
+#endif /* #ifndef URCU_MB */