rculfhash: check for callers from RCU read-side C.S.

[lttng-tools.git] / src / bin / lttng-sessiond / ust-registry.c

diff --git a/src/bin/lttng-sessiond/ust-registry.c b/src/bin/lttng-sessiond/ust-registry.c
index 19cff09fcd9d26aedb4a79194d10f7875e5fc810..b538a8fa9f37d6f5108c609a3021a27173cbe9ac 100644 (file)
--- a/src/bin/lttng-sessiond/ust-registry.c
+++ b/src/bin/lttng-sessiond/ust-registry.c
@@ -313,7 +313,7 @@ void ust_registry_destroy_event(struct ust_registry_channel *chan,
  * free the registry pointer since it might not have been allocated before so
  * it's the caller responsability.
  *
- * This MUST be called within a RCU read side lock section.
+ * This *MUST NOT* be called within a RCU read side lock section.
  */
 static void destroy_channel(struct ust_registry_channel *chan)
 {
@@ -322,13 +322,15 @@ static void destroy_channel(struct ust_registry_channel *chan)
 
        assert(chan);
 
+       rcu_read_lock();
        /* Destroy all event associated with this registry. */
        cds_lfht_for_each_entry(chan->ht->ht, &iter.iter, event, node.node) {
                /* Delete the node from the ht and free it. */
                ust_registry_destroy_event(chan, event);
        }
-       lttng_ht_destroy(chan->ht);
+       rcu_read_unlock();
 
+       lttng_ht_destroy(chan->ht);
        free(chan);
 }
 
@@ -418,22 +420,30 @@ void ust_registry_channel_del_free(struct ust_registry_session *session,
 {
        struct lttng_ht_iter iter;
        struct ust_registry_channel *chan;
+       int ret;
 
        assert(session);
 
        rcu_read_lock();
        chan = ust_registry_channel_find(session, key);
        if (!chan) {
+               rcu_read_unlock();
                goto end;
        }
 
        iter.iter.node = &chan->node.node;
-       lttng_ht_del(session->channels, &iter);
+       ret = lttng_ht_del(session->channels, &iter);
+       assert(!ret);
+       rcu_read_unlock();
 
+       /*
+        * Destroying the hash table should be done without RCU
+        * read-side lock held. Since we own "chan" now, it is OK to use
+        * it outside of RCU read-side critical section.
+        */
        destroy_channel(chan);
 
 end:
-       rcu_read_unlock();
        return;
 }
 
@@ -452,13 +462,14 @@ int ust_registry_session_init(struct ust_registry_session **sessionp,
                uint32_t uint32_t_alignment,
                uint32_t uint64_t_alignment,
                uint32_t long_alignment,
-               int byte_order)
+               int byte_order,
+               uint32_t major,
+               uint32_t minor)
 {
        int ret;
        struct ust_registry_session *session;
 
        assert(sessionp);
-       assert(app);
 
        session = zmalloc(sizeof(*session));
        if (!session) {
@@ -487,7 +498,7 @@ int ust_registry_session_init(struct ust_registry_session **sessionp,
        }
 
        pthread_mutex_lock(&session->lock);
-       ret = ust_metadata_session_statedump(session, app);
+       ret = ust_metadata_session_statedump(session, app, major, minor);
        pthread_mutex_unlock(&session->lock);
        if (ret) {
                ERR("Failed to generate session metadata (errno = %d)", ret);