X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=161680a6cdbda4ae27397efee2d6f4d694946083;hb=8382cf6f76c29b0451b7fe986c6b882d6029ca47;hp=5bec355486975a21d0417a9538728d4ea2f3822d;hpb=f86c9f4e9488dfd3eebb33fbec1b6afb1cd02630;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 5bec35548..161680a6c 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -916,7 +916,7 @@ int cmd_enable_channel(struct ltt_session *session,
 	 * Don't try to enable a channel if the session has been started at
 	 * some point in time before. The tracer does not allow it.
 	 */
-	if (session->started) {
+	if (session->has_been_started) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
@@ -939,15 +939,6 @@ int cmd_enable_channel(struct ltt_session *session,
 		kchan = trace_kernel_get_channel_by_name(attr->name,
 				session->kernel_session);
 		if (kchan == NULL) {
-			/*
-			 * Don't try to create a channel if the session
-			 * has been started at some point in time
-			 * before. The tracer does not allow it.
-			 */
-			if (session->started) {
-				ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-				goto error;
-			}
 			ret = channel_kernel_create(session->kernel_session, attr, wpipe);
 			if (attr->name[0] != '\0') {
 				session->kernel_session->has_non_default_channel = 1;
@@ -971,15 +962,6 @@ int cmd_enable_channel(struct ltt_session *session,
 
 		uchan = trace_ust_find_channel_by_name(chan_ht, attr->name);
 		if (uchan == NULL) {
-			/*
-			 * Don't try to create a channel if the session
-			 * has been started at some point in time
-			 * before. The tracer does not allow it.
-			 */
-			if (session->started) {
-				ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-				goto error;
-			}
 			ret = channel_ust_create(usess, attr, domain->buf_type);
 			if (attr->name[0] != '\0') {
 				usess->has_non_default_channel = 1;
@@ -1806,8 +1788,8 @@ int cmd_start_trace(struct ltt_session *session)
 	ksession = session->kernel_session;
 	usess = session->ust_session;
 
-	if (session->enabled) {
-		/* Already started. */
+	/* Is the session already started? */
+	if (session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
@@ -1827,8 +1809,6 @@ int cmd_start_trace(struct ltt_session *session)
 		goto error;
 	}
 
-	session->enabled = 1;
-
 	/* Kernel tracing */
 	if (ksession != NULL) {
 		ret = start_kernel_session(ksession, kernel_tracer_fd);
@@ -1848,7 +1828,9 @@ int cmd_start_trace(struct ltt_session *session)
 		}
 	}
 
-	session->started = 1;
+	/* Flag this after a successful start. */
+	session->has_been_started = 1;
+	session->active = 1;
 
 	ret = LTTNG_OK;
 
@@ -1872,13 +1854,12 @@ int cmd_stop_trace(struct ltt_session *session)
 	ksession = session->kernel_session;
 	usess = session->ust_session;
 
-	if (!session->enabled) {
+	/* Session is not active. Skip everythong and inform the client. */
+	if (!session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STOPPED;
 		goto error;
 	}
 
-	session->enabled = 0;
-
 	/* Kernel tracer */
 	if (ksession && ksession->started) {
 		DBG("Stop kernel tracing");
@@ -1920,6 +1901,8 @@ int cmd_stop_trace(struct ltt_session *session)
 		}
 	}
 
+	/* Flag inactive after a successful stop. */
+	session->active = 0;
 	ret = LTTNG_OK;
 
 error:
@@ -1941,8 +1924,8 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
 	assert(uris);
 	assert(nb_uri > 0);
 
-	/* Can't enable consumer after session started. */
-	if (session->enabled) {
+	/* Can't set consumer URI if the session is active. */
+	if (session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
@@ -2509,7 +2492,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
 
 		strncpy(sessions[i].name, session->name, NAME_MAX);
 		sessions[i].name[NAME_MAX - 1] = '\0';
-		sessions[i].enabled = session->enabled;
+		sessions[i].enabled = session->active;
 		sessions[i].snapshot_mode = session->snapshot_mode;
 		sessions[i].live_timer_interval = session->live_timer;
 		i++;
@@ -2529,9 +2512,24 @@ int cmd_data_pending(struct ltt_session *session)
 	assert(session);
 
 	/* Session MUST be stopped to ask for data availability. */
-	if (session->enabled) {
+	if (session->active) {
 		ret = LTTNG_ERR_SESSION_STARTED;
 		goto error;
+	} else {
+		/*
+		 * If stopped, just make sure we've started before else the above call
+		 * will always send that there is data pending.
+		 *
+		 * The consumer assumes that when the data pending command is received,
+		 * the trace has been started before or else no output data is written
+		 * by the streams which is a condition for data pending. So, this is
+		 * *VERY* important that we don't ask the consumer before a start
+		 * trace.
+		 */
+		if (!session->has_been_started) {
+			ret = 0;
+			goto error;
+		}
 	}
 
 	if (ksess && ksess->consumer) {
@@ -2962,7 +2960,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 	}
 
 	/* The session needs to be started at least once. */
-	if (!session->started) {
+	if (!session->has_been_started) {
 		ret = LTTNG_ERR_START_SESSION_ONCE;
 		goto error;
 	}