call_rcu: Fix race between rcu_barrier() and call_rcu_data_free()

[urcu.git] / src / urcu-call-rcu-impl.h

diff --git a/src/urcu-call-rcu-impl.h b/src/urcu-call-rcu-impl.h
index b6ec6ba3913fd1546a39485a3764a7488e7112bb..18fd65a0ec45b04de012dff83838f260cbe07bcb 100644 (file)
--- a/src/urcu-call-rcu-impl.h
+++ b/src/urcu-call-rcu-impl.h
@@ -772,9 +772,13 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
                while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0)
                        (void) poll(NULL, 0, 1);
        }
+       call_rcu_lock(&call_rcu_mutex);
        if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) {
-               /* Create default call rcu data if need be */
+               call_rcu_unlock(&call_rcu_mutex);
+               /* Create default call rcu data if need be. */
+               /* CBs queued here will be handed to the default list. */
                (void) get_default_call_rcu_data();
+               call_rcu_lock(&call_rcu_mutex);
                __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head,
                        &default_call_rcu_data->cbs_tail,
                        &crdp->cbs_head, &crdp->cbs_tail);
@@ -783,7 +787,6 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
                wake_call_rcu_thread(default_call_rcu_data);
        }
 
-       call_rcu_lock(&call_rcu_mutex);
        cds_list_del(&crdp->list);
        call_rcu_unlock(&call_rcu_mutex);