static pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
+int gp_futex;
+
/*
* Global grace period counter.
*/
}
}
+/*
+ * synchronize_rcu() waiting. Single thread.
+ */
+static void wait_gp(struct reader_registry *index)
+{
+ atomic_dec(&gp_futex);
+ smp_mb(); /* Write futex before read reader_gp */
+ if (!rcu_gp_ongoing(index->rcu_reader_qs_gp)) {
+ /* Read reader_gp before write futex */
+ smp_mb();
+ /* Callbacks are queued, don't wait. */
+ atomic_set(&gp_futex, 0);
+ } else {
+ /* Read reader_gp before read futex */
+ smp_rmb();
+ if (atomic_read(&gp_futex) == -1)
+ futex(&gp_futex, FUTEX_WAIT, -1,
+ NULL, NULL, 0);
+ }
+}
+
static void wait_for_quiescent_state(void)
{
struct reader_registry *index;
* Wait for each thread rcu_reader_qs_gp count to become 0.
*/
for (index = registry; index < registry + num_readers; index++) {
+ int wait_loops = 0;
+
+ while (rcu_gp_ongoing(index->rcu_reader_qs_gp)) {
+ if (wait_loops++ == RCU_QS_ACTIVE_ATTEMPTS) {
+ wait_gp(index);
+ } else {
#ifndef HAS_INCOHERENT_CACHES
- while (rcu_gp_ongoing(index->rcu_reader_qs_gp))
- cpu_relax();
+ cpu_relax();
#else /* #ifndef HAS_INCOHERENT_CACHES */
- while (rcu_gp_ongoing(index->rcu_reader_qs_gp))
- smp_mb();
+ smp_mb();
#endif /* #else #ifndef HAS_INCOHERENT_CACHES */
+ }
+ }
}
}
return STORE_SHARED(p, v);
}
+void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new)
+{
+ wmb();
+ return cmpxchg(p, old, _new);
+}
+
void *rcu_xchg_pointer_sym(void **p, void *v)
{
wmb();