void __attribute__((destructor)) rcu_bp_exit(void);
-static pthread_mutex_t rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
#ifdef DEBUG_YIELD
unsigned int yield_active;
static void rcu_gc_registry(void);
-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");
#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);
}
}
-/*
- * called with rcu_mutex held.
- */
-static void switch_next_rcu_qparity(void)
-{
- STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
-}
-
-void wait_for_quiescent_state(void)
+void update_counter_and_wait(void)
{
LIST_HEAD(qsreaders);
int wait_loops = 0;
struct rcu_reader *index, *tmp;
- if (list_empty(®istry))
- return;
+ /* Switch parity: 0 -> 1, 1 -> 0 */
+ STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+
+ /*
+ * Must commit qparity update to memory before waiting for other parity
+ * 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.
+ */
+
+ /*
+ * 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 each thread rcu_reader.ctr count to become 0.
*/
ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
assert(!ret);
- internal_rcu_lock();
+ mutex_lock(&rcu_gp_lock);
- /* Remove old registry elements */
- rcu_gc_registry();
+ if (list_empty(®istry))
+ goto out;
/* 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. */
/* Write new ptr before changing the qparity */
smp_mb();
- switch_next_rcu_qparity(); /* 0 -> 1 */
-
- /*
- * Must commit qparity update to memory before waiting for parity
- * 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.
- */
-
- /*
- * 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();
+ /* Remove old registry elements */
+ rcu_gc_registry();
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 0 */
-
- /*
- * Must finish waiting for quiescent state for parity 0 before
- * 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.
- */
+ update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */
/*
* Adding a smp_mb() which is _not_ formally required, but makes the
*/
smp_mb();
- switch_next_rcu_qparity(); /* 1 -> 0 */
-
/*
- * Must commit qparity update to memory before waiting for parity
- * 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.
- */
-
- /*
- * 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.
+ * Wait for previous parity to be empty of readers.
*/
- smp_mb();
+ update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */
/*
- * Wait for previous parity to be empty of readers.
+ * Finish waiting for reader threads before letting the old ptr being
+ * freed.
*/
- 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. */
smp_mb();
-
- internal_rcu_unlock();
+out:
+ mutex_unlock(&rcu_gp_lock);
ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
assert(!ret);
}
if (rcu_reader)
goto end;
- internal_rcu_lock();
+ mutex_lock(&rcu_gp_lock);
add_thread();
- internal_rcu_unlock();
+ mutex_unlock(&rcu_gp_lock);
end:
ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
assert(!ret);
projects / urcu.git / blobdiff