X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=urcu-call-rcu-impl.h;h=6ea7b9a05d74bdfb0c2760d426306d663cb0ade8;hb=refs%2Fheads%2Fstable-0.6;hp=36e3cf4b93a5904b5fc1e3d0ee84eccd1cc3d9ea;hpb=a0b7f7ea3fc3339a1c42caffd53ce9f056e5b901;p=urcu.git

diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h
index 36e3cf4..6ea7b9a 100644
--- a/urcu-call-rcu-impl.h
+++ b/urcu-call-rcu-impl.h
@@ -64,8 +64,9 @@ CDS_LIST_HEAD(call_rcu_data_list);
 
 static __thread struct call_rcu_data *thread_call_rcu_data;
 
-/* Guard call_rcu thread creation. */
-
+/*
+ * Guard call_rcu thread creation and atfork handlers.
+ */
 static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 /* If a given thread does not have its own call_rcu thread, this is default. */
@@ -239,6 +240,21 @@ static void *call_rcu_thread(void *arg)
 		cmm_smp_mb();
 	}
 	for (;;) {
+		if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) {
+			/*
+			 * Pause requested. Become quiescent: remove
+			 * ourself from all global lists, and don't
+			 * process any callback. The callback lists may
+			 * still be non-empty though.
+			 */
+			rcu_unregister_thread();
+			cmm_smp_mb__before_uatomic_or();
+			uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED);
+			while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0)
+				poll(NULL, 0, 1);
+			rcu_register_thread();
+		}
+
 		if (&crdp->cbs.head != _CMM_LOAD_SHARED(crdp->cbs.tail)) {
 			while ((cbs = _CMM_LOAD_SHARED(crdp->cbs.head)) == NULL)
 				poll(NULL, 0, 1);
@@ -645,8 +661,9 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
 		/* Create default call rcu data if need be */
 		(void) get_default_call_rcu_data();
 		cbs_endprev = (struct cds_wfq_node **)
-			uatomic_xchg(&default_call_rcu_data, cbs_tail);
-		*cbs_endprev = cbs;
+			uatomic_xchg(&default_call_rcu_data->cbs.tail,
+					cbs_tail);
+		_CMM_STORE_SHARED(*cbs_endprev, cbs);
 		uatomic_add(&default_call_rcu_data->qlen,
 			    uatomic_read(&crdp->qlen));
 		wake_call_rcu_thread(default_call_rcu_data);
@@ -701,12 +718,25 @@ void free_all_cpu_call_rcu_data(void)
 
 /*
  * Acquire the call_rcu_mutex in order to ensure that the child sees
- * all of the call_rcu() data structures in a consistent state.
+ * all of the call_rcu() data structures in a consistent state. Ensure
+ * that all call_rcu threads are in a quiescent state across fork.
  * Suitable for pthread_atfork() and friends.
  */
 void call_rcu_before_fork(void)
 {
+	struct call_rcu_data *crdp;
+
 	call_rcu_lock(&call_rcu_mutex);
+
+	cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
+		uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSE);
+		cmm_smp_mb__after_uatomic_or();
+		wake_call_rcu_thread(crdp);
+	}
+	cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
+		while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) == 0)
+			poll(NULL, 0, 1);
+	}
 }
 
 /*
@@ -716,6 +746,10 @@ void call_rcu_before_fork(void)
  */
 void call_rcu_after_fork_parent(void)
 {
+	struct call_rcu_data *crdp;
+
+	cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
+		uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE);
 	call_rcu_unlock(&call_rcu_mutex);
 }
 
@@ -748,7 +782,11 @@ void call_rcu_after_fork_child(void)
 	rcu_set_pointer(&per_cpu_call_rcu_data, NULL);
 	thread_call_rcu_data = NULL;
 
-	/* Dispose of all of the rest of the call_rcu_data structures. */
+	/*
+	 * Dispose of all of the rest of the call_rcu_data structures.
+	 * Leftover call_rcu callbacks will be merged into the new
+	 * default call_rcu thread queue.
+	 */
 	cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) {
 		if (crdp == default_call_rcu_data)
 			continue;