Fix: add-context cannot be performed after a session has been started

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

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index a295059fbf487ef237e97d31ffccbd9fb248fdd1..1a3c22a6c8f87715dc85c878ec5b0c3443d7d1e3 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -907,6 +907,8 @@ error:
 
 /*
  * Connect to the relayd using URI and send the socket to the right consumer.
+ *
+ * The consumer socket lock must be held by the caller.
  */
 static int send_consumer_relayd_socket(enum lttng_domain_type domain,
                unsigned int session_id, struct lttng_uri *relayd_uri,
@@ -920,7 +922,7 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
        /* Connect to relayd and make version check if uri is the control. */
        ret = create_connect_relayd(relayd_uri, &rsock, consumer);
        if (ret != LTTNG_OK) {
-               goto error;
+               goto relayd_comm_error;
        }
        assert(rsock);
 
@@ -960,10 +962,6 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
         */
 
 close_sock:
-       (void) relayd_close(rsock);
-       free(rsock);
-
-error:
        if (ret != LTTNG_OK) {
                /*
                 * The consumer output for this session should not be used anymore
@@ -972,6 +970,10 @@ error:
                 */
                consumer->enabled = 0;
        }
+       (void) relayd_close(rsock);
+       free(rsock);
+
+relayd_comm_error:
        return ret;
 }
 
@@ -979,6 +981,8 @@ error:
  * Send both relayd sockets to a specific consumer and domain.  This is a
  * helper function to facilitate sending the information to the consumer for a
  * session.
+ *
+ * The consumer socket lock must be held by the caller.
  */
 static int send_consumer_relayd_sockets(enum lttng_domain_type domain,
                unsigned int session_id, struct consumer_output *consumer,
@@ -1650,6 +1654,16 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
        int ret, chan_kern_created = 0, chan_ust_created = 0;
        char *app_ctx_provider_name = NULL, *app_ctx_name = NULL;
 
+       /*
+        * Don't try to add a context if the session has been started at
+        * some point in time before. The tracer does not allow it and would
+        * result in a corrupted trace.
+        */
+       if (session->has_been_started) {
+               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+               goto end;
+       }
+
        if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
                app_ctx_provider_name = ctx->u.app_ctx.provider_name;
                app_ctx_name = ctx->u.app_ctx.ctx_name;
@@ -3706,10 +3720,12 @@ static int set_relayd_for_snapshot(struct consumer_output *consumer,
        rcu_read_lock();
        cds_lfht_for_each_entry(snap_output->consumer->socks->ht, &iter.iter,
                        socket, node.node) {
+               pthread_mutex_lock(socket->lock);
                ret = send_consumer_relayd_sockets(0, session->id,
                                snap_output->consumer, socket,
                                session->name, session->hostname,
                                session->live_timer);
+               pthread_mutex_unlock(socket->lock);
                if (ret != LTTNG_OK) {
                        rcu_read_unlock();
                        goto error;