trigger: implement trigger naming

[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 d8d17b59cba2b07956ff7e08bf13c685dfca37da..86a162baf1f6ddfcefdaf729a286eec7ff8d20e1 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -4257,7 +4257,8 @@ end:
 }
 
 int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
-               struct notification_thread_handle *notification_thread)
+               struct notification_thread_handle *notification_thread,
+               struct lttng_trigger **return_trigger)
 {
        int ret;
        size_t trigger_len;
@@ -4314,7 +4315,6 @@ int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
                }
        }
 
-
        /*
         * Validate the trigger credentials against the command credentials.
         * Only the root user can register a trigger with non-matching
@@ -4330,9 +4330,26 @@ int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
                }
        }
 
-       /* Inform the notification thread */
+       /*
+        * A reference to the trigger is acquired by the notification thread.
+        * It is safe to return the same trigger to the caller since it the
+        * other user holds a reference.
+        *
+        * The trigger is modified during the execution of the
+        * "register trigger" command. However, by the time the command returns,
+        * it is safe to use without any locking as its properties are
+        * immutable.
+        */
        ret = notification_thread_command_register_trigger(notification_thread,
                        trigger);
+       if (ret != LTTNG_OK) {
+               goto end_notification_thread;
+       }
+
+       /* Return an updated trigger to the client. */
+       *return_trigger = trigger;
+
+end_notification_thread:
        /* Ownership of trigger was transferred. */
        trigger = NULL;
 end: