Add a create_ust_stream function in ust-app.c

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

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 7da843a9e0a1d1bb56ba896e8283d28fec301358..8f7db8f2ccbda06e5584a93f332576b70a62b9a9 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -721,9 +721,9 @@ error:
 }
 
 /*
- * Create stream onto the UST tracer for a UST session.
+ * Create metadata stream onto the UST tracer for a given session.
  */
-static int create_ust_stream(struct ust_app *app,
+static int create_ust_metadata_stream(struct ust_app *app,
                struct ust_app_session *ua_sess)
 {
        int ret;
@@ -748,6 +748,52 @@ error:
        return ret;
 }
 
+/*
+ * Create stream onto the UST tracer for a given channel.
+ *
+ * Return -ENOENT if no more stream is available for this channel.
+ * On success, return 0.
+ * On error, return a negative value.
+ */
+static int create_ust_stream(struct ust_app *app,
+               struct ust_app_channel *ua_chan, struct ltt_ust_stream *stream)
+{
+       int ret;
+
+       assert(app);
+       assert(ua_chan);
+       assert(ua_chan->obj);
+       assert(stream);
+
+       health_code_update(&health_thread_cmd);
+
+       /* We are going to receive 2 fds, we need to reserve them. */
+       ret = lttng_fd_get(LTTNG_FD_APPS, 2);
+       if (ret < 0) {
+               ERR("Exhausted number of available FD on stream creation");
+               /* Just to make sure we never return -ENOENT. */
+               ret = -1;
+               goto error;
+       }
+
+       ret = ustctl_create_stream(app->sock, ua_chan->obj, &stream->obj);
+       if (ret < 0) {
+               lttng_fd_put(LTTNG_FD_APPS, 2);
+               /* Indicates that there is no more stream for that channel. */
+               if (ret != -ENOENT) {
+                       ERR("UST create metadata stream failed (ret: %d)", ret);
+               }
+               goto error;
+       }
+
+       /* Set stream handle with the returned value. */
+       stream->handle = stream->obj->handle;
+
+error:
+       health_code_update(&health_thread_cmd);
+       return ret;
+}
+
 /*
  * Create the specified channel onto the UST tracer for a UST session.
  */
@@ -1375,7 +1421,7 @@ static int create_ust_app_metadata(struct ust_app_session *ua_sess,
 
        /* Open UST metadata stream */
        if (ua_sess->metadata->stream_obj == NULL) {
-               ret = create_ust_stream(app, ua_sess);
+               ret = create_ust_metadata_stream(app, ua_sess);
                if (ret < 0) {
                        goto error;
                }
@@ -2307,26 +2353,20 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
                                goto error_rcu_unlock;
                        }
 
-                       /* We are going to receive 2 fds, we need to reserve them. */
-                       ret = lttng_fd_get(LTTNG_FD_APPS, 2);
-                       if (ret < 0) {
-                               ERR("Exhausted number of available FD upon stream create");
-                               free(ustream);
-                               goto error_rcu_unlock;
-                       }
-
                        health_code_update(&health_thread_cmd);
 
-                       ret = ustctl_create_stream(app->sock, ua_chan->obj,
-                                       &ustream->obj);
+                       ret = create_ust_stream(app, ua_chan, ustream);
                        if (ret < 0) {
-                               /* Got all streams */
-                               lttng_fd_put(LTTNG_FD_APPS, 2);
+                               /* Free unused memory after this point. */
                                free(ustream);
+                               if (ret == -ENOENT) {
+                                       /* Got all streams. Continue normal execution. */
+                                       break;
+                               }
+                               /* Error at this point. Stop everything. */
                                ret = LTTNG_ERR_UST_STREAM_FAIL;
-                               break;
+                               goto error_rcu_unlock;
                        }
-                       ustream->handle = ustream->obj->handle;
 
                        health_code_update(&health_thread_cmd);