Fix possible NULL UST session on start trace

[lttng-tools.git] / lttng-sessiond / ust-app.c

diff --git a/lttng-sessiond/ust-app.c b/lttng-sessiond/ust-app.c
index e063fb292ad80511f45331896704bba555898d14..99fd84f3e07ca5982875ab257dd7f2146d9c225f 100644 (file)
--- a/lttng-sessiond/ust-app.c
+++ b/lttng-sessiond/ust-app.c
@@ -113,7 +113,6 @@ static struct ust_app *find_app_by_sock(int sock)
                        (void *)((unsigned long) sock), sizeof(void *), &iter);
        if (node == NULL) {
                DBG2("UST app find by sock %d key not found", sock);
-               rcu_read_unlock();
                goto error;
        }
 
@@ -123,7 +122,6 @@ static struct ust_app *find_app_by_sock(int sock)
                        (void *)((unsigned long) key->pid), sizeof(void *), &iter);
        if (node == NULL) {
                DBG2("UST app find by sock %d not found", sock);
-               rcu_read_unlock();
                goto error;
        }
 
@@ -153,7 +151,6 @@ struct ust_app *ust_app_find_by_pid(pid_t pid)
        node = hashtable_lookup(ust_app_ht,
                        (void *)((unsigned long) pid), sizeof(void *), &iter);
        if (node == NULL) {
-               rcu_read_unlock();
                DBG2("UST app no found with pid %d", pid);
                goto error;
        }
@@ -164,6 +161,7 @@ struct ust_app *ust_app_find_by_pid(pid_t pid)
        return caa_container_of(node, struct ust_app, node);
 
 error:
+       rcu_read_unlock();
        return NULL;
 }
 
@@ -808,7 +806,7 @@ int ust_app_add_channel_all(struct ltt_ust_session *usess,
 
                /* Create session on the tracer side and add it to app session HT */
                ua_sess = create_ust_app_session(usess, app);
-               if (ret < 0) {
+               if (ua_sess == NULL) {
                        goto next;
                }
 
@@ -851,7 +849,7 @@ int ust_app_add_event_all(struct ltt_ust_session *usess,
 
                /* Create session on the tracer side and add it to app session HT */
                ua_sess = create_ust_app_session(usess, app);
-               if (ret < 0) {
+               if (ua_sess == NULL) {
                        goto next;
                }
 
@@ -889,15 +887,17 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
 
        DBG("Starting tracing for ust app pid %d", app->key.pid);
 
+       rcu_read_lock();
+
        ua_sess = lookup_session_by_app(usess, app);
        if (ua_sess == NULL) {
                /* Only malloc can failed so something is really wrong */
-               goto error;
+               goto error_rcu_unlock;
        }
 
        ret = create_ust_app_metadata(ua_sess, usess->pathname, app);
        if (ret < 0) {
-               goto error;
+               goto error_rcu_unlock;
        }
 
        /* For each channel */
@@ -912,7 +912,7 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
                        ustream = zmalloc(sizeof(*ustream));
                        if (ustream == NULL) {
                                PERROR("zmalloc ust stream");
-                               continue;
+                               goto error_rcu_unlock;
                        }
 
                        ret = ustctl_create_stream(app->key.sock, ua_chan->obj,
@@ -943,22 +943,24 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
        /* Setup UST consumer socket and send fds to it */
        ret = ust_consumer_send_session(usess->consumer_fd, ua_sess);
        if (ret < 0) {
-               goto error;
+               goto error_rcu_unlock;
        }
 
        /* This start the UST tracing */
        ret = ustctl_start_session(app->key.sock, ua_sess->handle);
        if (ret < 0) {
                ERR("Error starting tracing for app pid: %d", app->key.pid);
-               goto error;
+               goto error_rcu_unlock;
        }
+       rcu_read_unlock();
 
        /* Quiescent wait after starting trace */
        ustctl_wait_quiescent(app->key.sock);
 
        return 0;
 
-error:
+error_rcu_unlock:
+       rcu_read_unlock();
        return -1;
 }