Fix: missing rcu_read_lock in cmd_start_trace()

[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 4a7fadaf5231d4f3c84d33d7956f68f11dd998d5..ed994a966ebe3c534b2a27991632d457ffdeecb1 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -1446,7 +1446,32 @@ int create_ust_event(struct ust_app *app, struct ust_app_session *ua_sess,
        }
 
        /* If event not enabled, disable it on the tracer */
-       if (ua_event->enabled == 0) {
+       if (ua_event->enabled) {
+               /*
+                * We now need to explicitly enable the event, since it
+                * is now disabled at creation.
+                */
+               ret = enable_ust_event(app, ua_sess, ua_event);
+               if (ret < 0) {
+                       /*
+                        * If we hit an EPERM, something is wrong with our enable call. If
+                        * we get an EEXIST, there is a problem on the tracer side since we
+                        * just created it.
+                        */
+                       switch (ret) {
+                       case -LTTNG_UST_ERR_PERM:
+                               /* Code flow problem */
+                               assert(0);
+                       case -LTTNG_UST_ERR_EXIST:
+                               /* It's OK for our use case. */
+                               ret = 0;
+                               break;
+                       default:
+                               break;
+                       }
+                       goto error;
+               }
+       } else {
                ret = disable_ust_event(app, ua_sess, ua_event);
                if (ret < 0) {
                        /*
@@ -2450,6 +2475,8 @@ static int create_channel_per_uid(struct ust_app *app,
                /* Create the buffer registry channel object. */
                ret = create_buffer_reg_channel(reg_uid->registry, ua_chan, &reg_chan);
                if (ret < 0) {
+                       ERR("Error creating the UST channel \"%s\" registry instance",
+                               ua_chan->name);
                        goto error;
                }
                assert(reg_chan);
@@ -2461,6 +2488,9 @@ static int create_channel_per_uid(struct ust_app *app,
                ret = do_consumer_create_channel(usess, ua_sess, ua_chan,
                                app->bits_per_long, reg_uid->registry->reg.ust);
                if (ret < 0) {
+                       ERR("Error creating UST channel \"%s\" on the consumer daemon",
+                               ua_chan->name);
+
                        /*
                         * Let's remove the previously created buffer registry channel so
                         * it's not visible anymore in the session registry.
@@ -2477,6 +2507,8 @@ static int create_channel_per_uid(struct ust_app *app,
                 */
                ret = setup_buffer_reg_channel(reg_uid->registry, ua_chan, reg_chan);
                if (ret < 0) {
+                       ERR("Error setting up UST channel \"%s\"",
+                               ua_chan->name);
                        goto error;
                }
 
@@ -2485,6 +2517,10 @@ static int create_channel_per_uid(struct ust_app *app,
        /* Send buffers to the application. */
        ret = send_channel_uid_to_ust(reg_chan, app, ua_sess, ua_chan);
        if (ret < 0) {
+               /*
+                * Don't report error to the console, since it may be
+                * caused by application concurrently exiting.
+                */
                goto error;
        }
 
@@ -2519,6 +2555,8 @@ static int create_channel_per_pid(struct ust_app *app,
        /* Create and add a new channel registry to session. */
        ret = ust_registry_channel_add(registry, ua_chan->key);
        if (ret < 0) {
+               ERR("Error creating the UST channel \"%s\" registry instance",
+                       ua_chan->name);
                goto error;
        }
 
@@ -2526,11 +2564,17 @@ static int create_channel_per_pid(struct ust_app *app,
        ret = do_consumer_create_channel(usess, ua_sess, ua_chan,
                        app->bits_per_long, registry);
        if (ret < 0) {
+               ERR("Error creating UST channel \"%s\" on the consumer daemon",
+                       ua_chan->name);
                goto error;
        }
 
        ret = send_channel_pid_to_ust(app, ua_sess, ua_chan);
        if (ret < 0) {
+               /*
+                * Don't report error to the console, since it may be
+                * caused by application concurrently exiting.
+                */
                goto error;
        }