Fix: don't set enabled flag is session start fails

[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 36fe233ae8fc8681c0a90ef8b854d76af01c888e..8a17dd62a0ce39fc3e980fb9fd64bb78fe125207 100644 (file)
--- 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;
        }
@@ -931,6 +931,16 @@ int cmd_enable_channel(struct ltt_session *session,
                attr->attr.switch_timer_interval = 0;
        }
 
+       /*
+        * The ringbuffer (both in user space and kernel) behave badly in overwrite
+        * mode and with less than 2 subbuf so block it right away and send back an
+        * invalid attribute error.
+        */
+       if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+               ret = LTTNG_ERR_INVALID;
+               goto error;
+       }
+
        switch (domain->type) {
        case LTTNG_DOMAIN_KERNEL:
        {
@@ -939,15 +949,6 @@ 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 +972,6 @@ 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;
@@ -1461,7 +1453,7 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                tmp_dom.type = LTTNG_DOMAIN_UST;
 
                ret = cmd_enable_event(session, &tmp_dom, DEFAULT_JUL_CHANNEL_NAME,
-                               &uevent, NULL, NULL, wpipe);
+                               &uevent, filter, NULL, wpipe);
                if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_ENABLED) {
                        goto error;
                }
@@ -1802,8 +1794,8 @@ 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;
        }
@@ -1823,8 +1815,6 @@ 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);
@@ -1844,7 +1834,9 @@ 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;
 
@@ -1868,13 +1860,12 @@ 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");
@@ -1916,6 +1907,8 @@ int cmd_stop_trace(struct ltt_session *session)
                }
        }
 
+       /* Flag inactive after a successful stop. */
+       session->active = 0;
        ret = LTTNG_OK;
 
 error:
@@ -1937,8 +1930,8 @@ 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;
        }
@@ -1978,6 +1971,17 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
                }
        }
 
+       /*
+        * Make sure to set the session in output mode after we set URI since a
+        * session can be created without URL (thus flagged in no output mode).
+        */
+       session->output_traces = 1;
+       if (ksess) {
+               ksess->output_traces = 1;
+       } else if (usess) {
+               usess->output_traces = 1;
+       }
+
        /* All good! */
        ret = LTTNG_OK;
 
@@ -2505,7 +2509,7 @@ 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++;
@@ -2525,7 +2529,7 @@ 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 {
@@ -2539,7 +2543,7 @@ int cmd_data_pending(struct ltt_session *session)
                 * *VERY* important that we don't ask the consumer before a start
                 * trace.
                 */
-               if (!session->started) {
+               if (!session->has_been_started) {
                        ret = 0;
                        goto error;
                }
@@ -2973,7 +2977,7 @@ 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;
        }