From: David Goulet <dgoulet@efficios.com>
Date: Mon, 21 Jan 2013 16:25:09 +0000 (-0500)
Subject: Add a create_ust_stream function in ust-app.c
X-Git-Tag: v2.2.0-rc1~105
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=4f3ab6ee347964379eefc57f41f8a381965b4316;p=lttng-tools.git

Add a create_ust_stream function in ust-app.c

This helps by having a single callsite for ustctl_create_stream and
removes the need for the caller to handle FD reservation. On success,
the function sets the returned handle to the given stream.

Signed-off-by: David Goulet <dgoulet@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 22b395773..8f7db8f2c 100644
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -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.
  */
@@ -2307,22 +2353,12 @@ 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) {
-				/* Free unused memory and reset FD states. */
+				/* Free unused memory after this point. */
 				free(ustream);
-				lttng_fd_put(LTTNG_FD_APPS, 2);
 				if (ret == -ENOENT) {
 					/* Got all streams. Continue normal execution. */
 					break;
@@ -2331,7 +2367,6 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
 				ret = LTTNG_ERR_UST_STREAM_FAIL;
 				goto error_rcu_unlock;
 			}
-			ustream->handle = ustream->obj->handle;
 
 			health_code_update(&health_thread_cmd);