Fix: sessiond: session destroy hang in per-uid when context cannot be added

[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 d130f116a4e95d53313e954f6001e9846956a53f..65d27bbe923f094d0b4a5c7974b9cc37900c2c61 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -45,6 +45,10 @@
 #include "notification-thread-commands.h"
 #include "rotate.h"
 
+struct lttng_ht *ust_app_ht;
+struct lttng_ht *ust_app_ht_by_sock;
+struct lttng_ht *ust_app_ht_by_notify_sock;
+
 static
 int ust_app_flush_app_session(struct ust_app *app, struct ust_app_session *ua_sess);
 
@@ -2494,7 +2498,7 @@ static int do_consumer_create_channel(struct ltt_ust_session *usess,
        health_code_update();
 
        /*
-        * Now get the channel from the consumer. This call wil populate the stream
+        * Now get the channel from the consumer. This call will populate the stream
         * list of that channel and set the ust objects.
         */
        if (usess->consumer->enabled) {
@@ -4118,11 +4122,14 @@ int ust_app_channel_create(struct ltt_ust_session *usess,
                ret = ust_app_channel_allocate(ua_sess, uchan,
                        LTTNG_UST_CHAN_PER_CPU, usess,
                        &ua_chan);
-               if (ret == 0) {
-                       ret = ust_app_channel_send(app, usess,
-                               ua_sess, ua_chan);
-               } else {
-                       goto end;
+               if (ret < 0) {
+                       goto error;
+               }
+
+               ret = ust_app_channel_send(app, usess,
+                       ua_sess, ua_chan);
+               if (ret) {
+                       goto error;
                }
 
                /* Add contexts. */
@@ -4130,10 +4137,12 @@ int ust_app_channel_create(struct ltt_ust_session *usess,
                        ret = create_ust_app_channel_context(ua_chan,
                                &uctx->ctx, app);
                        if (ret) {
-                               goto end;
+                               goto error;
                        }
                }
        }
+
+error:
        if (ret < 0) {
                switch (ret) {
                case -ENOTCONN:
@@ -4149,7 +4158,7 @@ int ust_app_channel_create(struct ltt_ust_session *usess,
                        break;
                }
        }
-end:
+
        if (ret == 0 && _ua_chan) {
                /*
                 * Only return the application's channel on success. Note
@@ -4421,15 +4430,6 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
                goto skip_setup;
        }
 
-       /*
-        * Create the metadata for the application. This returns gracefully if a
-        * metadata was already set for the session.
-        */
-       ret = create_ust_app_metadata(ua_sess, app, usess->consumer);
-       if (ret < 0) {
-               goto error_unlock;
-       }
-
        health_code_update();
 
 skip_setup:
@@ -5095,6 +5095,7 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
        }
 
        rcu_read_lock();
+
        cds_lfht_for_each_entry(usess->domain_global.channels->ht, &uchan_iter,
                        uchan, node.node) {
                struct ust_app_channel *ua_chan;
@@ -5138,6 +5139,21 @@ void ust_app_synchronize(struct ltt_ust_session *usess,
                        }
                }
        }
+
+       /*
+        * Create the metadata for the application. This returns gracefully if a
+        * metadata was already set for the session.
+        *
+        * The metadata channel must be created after the data channels as the
+        * consumer daemon assumes this ordering. When interacting with a relay
+        * daemon, the consumer will use this assumption to send the
+        * "STREAMS_SENT" message to the relay daemon.
+        */
+       ret = create_ust_app_metadata(ua_sess, app, usess->consumer);
+       if (ret < 0) {
+               goto error_unlock;
+       }
+
        rcu_read_unlock();
 
 end:
@@ -6347,6 +6363,19 @@ enum lttng_error_code ust_app_rotate_session(struct ltt_session *session)
                                }
                        }
 
+                       /*
+                        * The metadata channel might not be present.
+                        *
+                        * Consumer stream allocation can be done
+                        * asynchronously and can fail on intermediary
+                        * operations (i.e add context) and lead to data
+                        * channels created with no metadata channel.
+                        */
+                       if (!reg->registry->reg.ust->metadata_key) {
+                               /* Skip since no metadata is present. */
+                               continue;
+                       }
+
                        (void) push_metadata(reg->registry->reg.ust, usess->consumer);
 
                        ret = consumer_rotate_channel(socket,
@@ -6486,6 +6515,17 @@ enum lttng_error_code ust_app_create_channel_subdirectories(
        {
                struct ust_app *app;
 
+               /*
+                * Create the toplevel ust/ directory in case no apps are running.
+                */
+               chunk_status = lttng_trace_chunk_create_subdirectory(
+                               usess->current_trace_chunk,
+                               DEFAULT_UST_TRACE_DIR);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret = LTTNG_ERR_CREATE_DIR_FAIL;
+                       goto error;
+               }
+
                cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app,
                                pid_n.node) {
                        struct ust_app_session *ua_sess;