Fix: FD leak on consumer add relayd socket error
[lttng-tools.git] / src / common / consumer.c
index cf1b7b96f95a6c09897d44b9f6d735013513d035..5766860a89823bf40c4ebd98448fc233e54c06f2 100644 (file)
@@ -47,16 +47,36 @@ struct lttng_consumer_global_data consumer_data = {
        .type = LTTNG_CONSUMER_UNKNOWN,
 };
 
-/* timeout parameter, to control the polling thread grace period. */
-int consumer_poll_timeout = -1;
-
 /*
  * Flag to inform the polling thread to quit when all fd hung up. Updated by
  * the consumer_thread_receive_fds when it notices that all fds has hung up.
  * Also updated by the signal handler (consumer_should_exit()). Read by the
  * polling threads.
  */
-volatile int consumer_quit = 0;
+volatile int consumer_quit;
+
+/*
+ * Global hash table containing respectively metadata and data streams. The
+ * stream element in this ht should only be updated by the metadata poll thread
+ * for the metadata and the data poll thread for the data.
+ */
+static struct lttng_ht *metadata_ht;
+static struct lttng_ht *data_ht;
+
+/*
+ * Notify a thread pipe to poll back again. This usually means that some global
+ * state has changed so we just send back the thread in a poll wait call.
+ */
+static void notify_thread_pipe(int wpipe)
+{
+       int ret;
+
+       do {
+               struct lttng_consumer_stream *null_stream = NULL;
+
+               ret = write(wpipe, &null_stream, sizeof(null_stream));
+       } while (ret < 0 && errno == EINTR);
+}
 
 /*
  * Find a stream. The consumer_data.lock must be locked during this
@@ -89,7 +109,7 @@ static struct lttng_consumer_stream *consumer_find_stream(int key,
        return stream;
 }
 
-static void consumer_steal_stream_key(int key, struct lttng_ht *ht)
+void consumer_steal_stream_key(int key, struct lttng_ht *ht)
 {
        struct lttng_consumer_stream *stream;
 
@@ -107,6 +127,12 @@ static void consumer_steal_stream_key(int key, struct lttng_ht *ht)
        rcu_read_unlock();
 }
 
+/*
+ * Return a channel object for the given key.
+ *
+ * RCU read side lock MUST be acquired before calling this function and
+ * protects the channel ptr.
+ */
 static struct lttng_consumer_channel *consumer_find_channel(int key)
 {
        struct lttng_ht_iter iter;
@@ -118,8 +144,6 @@ static struct lttng_consumer_channel *consumer_find_channel(int key)
                return NULL;
        }
 
-       rcu_read_lock();
-
        lttng_ht_lookup(consumer_data.channel_ht, (void *)((unsigned long) key),
                        &iter);
        node = lttng_ht_iter_get_node_ulong(&iter);
@@ -127,8 +151,6 @@ static struct lttng_consumer_channel *consumer_find_channel(int key)
                channel = caa_container_of(node, struct lttng_consumer_channel, node);
        }
 
-       rcu_read_unlock();
-
        return channel;
 }
 
@@ -161,17 +183,6 @@ void consumer_free_stream(struct rcu_head *head)
        free(stream);
 }
 
-static
-void consumer_free_metadata_stream(struct rcu_head *head)
-{
-       struct lttng_ht_node_ulong *node =
-               caa_container_of(head, struct lttng_ht_node_ulong, head);
-       struct lttng_consumer_stream *stream =
-               caa_container_of(node, struct lttng_consumer_stream, waitfd_node);
-
-       free(stream);
-}
-
 /*
  * RCU protected relayd socket pair free.
  */
@@ -182,6 +193,17 @@ static void consumer_rcu_free_relayd(struct rcu_head *head)
        struct consumer_relayd_sock_pair *relayd =
                caa_container_of(node, struct consumer_relayd_sock_pair, node);
 
+       /*
+        * Close all sockets. This is done in the call RCU since we don't want the
+        * socket fds to be reassigned thus potentially creating bad state of the
+        * relayd object.
+        *
+        * We do not have to lock the control socket mutex here since at this stage
+        * there is no one referencing to this relayd object.
+        */
+       (void) relayd_close(&relayd->control_sock);
+       (void) relayd_close(&relayd->data_sock);
+
        free(relayd);
 }
 
@@ -204,20 +226,90 @@ static void destroy_relayd(struct consumer_relayd_sock_pair *relayd)
        iter.iter.node = &relayd->node.node;
        ret = lttng_ht_del(consumer_data.relayd_ht, &iter);
        if (ret != 0) {
-               /* We assume the relayd was already destroyed */
+               /* We assume the relayd is being or is destroyed */
                return;
        }
 
-       /* Close all sockets */
-       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-       (void) relayd_close(&relayd->control_sock);
-       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-       (void) relayd_close(&relayd->data_sock);
-
        /* RCU free() call */
        call_rcu(&relayd->node.head, consumer_rcu_free_relayd);
 }
 
+/*
+ * Update the end point status of all streams having the given network sequence
+ * index (relayd index).
+ *
+ * It's atomically set without having the stream mutex locked which is fine
+ * because we handle the write/read race with a pipe wakeup for each thread.
+ */
+static void update_endpoint_status_by_netidx(int net_seq_idx,
+               enum consumer_endpoint_status status)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer set delete flag on stream by idx %d", net_seq_idx);
+
+       rcu_read_lock();
+
+       /* Let's begin with metadata */
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
+               if (stream->net_seq_idx == net_seq_idx) {
+                       uatomic_set(&stream->endpoint_status, status);
+                       DBG("Delete flag set to metadata stream %d", stream->wait_fd);
+               }
+       }
+
+       /* Follow up by the data streams */
+       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
+               if (stream->net_seq_idx == net_seq_idx) {
+                       uatomic_set(&stream->endpoint_status, status);
+                       DBG("Delete flag set to data stream %d", stream->wait_fd);
+               }
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Cleanup a relayd object by flagging every associated streams for deletion,
+ * destroying the object meaning removing it from the relayd hash table,
+ * closing the sockets and freeing the memory in a RCU call.
+ *
+ * If a local data context is available, notify the threads that the streams'
+ * state have changed.
+ */
+static void cleanup_relayd(struct consumer_relayd_sock_pair *relayd,
+               struct lttng_consumer_local_data *ctx)
+{
+       int netidx;
+
+       assert(relayd);
+
+       DBG("Cleaning up relayd sockets");
+
+       /* Save the net sequence index before destroying the object */
+       netidx = relayd->net_seq_idx;
+
+       /*
+        * Delete the relayd from the relayd hash table, close the sockets and free
+        * the object in a RCU call.
+        */
+       destroy_relayd(relayd);
+
+       /* Set inactive endpoint to all streams */
+       update_endpoint_status_by_netidx(netidx, CONSUMER_ENDPOINT_INACTIVE);
+
+       /*
+        * With a local data context, notify the threads that the streams' state
+        * have changed. The write() action on the pipe acts as an "implicit"
+        * memory barrier ordering the updates of the end point status from the
+        * read of this status which happens AFTER receiving this notify.
+        */
+       if (ctx) {
+               notify_thread_pipe(ctx->consumer_data_pipe[1]);
+               notify_thread_pipe(ctx->consumer_metadata_pipe[1]);
+       }
+}
+
 /*
  * Flag a relayd socket pair for destruction. Destroy it if the refcount
  * reaches zero.
@@ -251,12 +343,15 @@ void consumer_del_stream(struct lttng_consumer_stream *stream,
 
        assert(stream);
 
+       DBG("Consumer del stream %d", stream->wait_fd);
+
        if (ht == NULL) {
                /* Means the stream was allocated but not successfully added */
                goto free_stream;
        }
 
        pthread_mutex_lock(&consumer_data.lock);
+       pthread_mutex_lock(&stream->lock);
 
        switch (consumer_data.type) {
        case LTTNG_CONSUMER_KERNEL:
@@ -282,15 +377,15 @@ void consumer_del_stream(struct lttng_consumer_stream *stream,
        ret = lttng_ht_del(ht, &iter);
        assert(!ret);
 
+       /* Remove node session id from the consumer_data stream ht */
+       iter.iter.node = &stream->node_session_id.node;
+       ret = lttng_ht_del(consumer_data.stream_list_ht, &iter);
+       assert(!ret);
        rcu_read_unlock();
 
-       if (consumer_data.stream_count <= 0) {
-               goto end;
-       }
+       assert(consumer_data.stream_count > 0);
        consumer_data.stream_count--;
-       if (!stream) {
-               goto end;
-       }
+
        if (stream->out_fd >= 0) {
                ret = close(stream->out_fd);
                if (ret) {
@@ -348,6 +443,7 @@ void consumer_del_stream(struct lttng_consumer_stream *stream,
 
 end:
        consumer_data.need_update = 1;
+       pthread_mutex_unlock(&stream->lock);
        pthread_mutex_unlock(&consumer_data.lock);
 
        if (free_chan) {
@@ -369,6 +465,7 @@ struct lttng_consumer_stream *consumer_allocate_stream(
                gid_t gid,
                int net_index,
                int metadata_flag,
+               uint64_t session_id,
                int *alloc_ret)
 {
        struct lttng_consumer_stream *stream;
@@ -380,6 +477,8 @@ struct lttng_consumer_stream *consumer_allocate_stream(
                goto end;
        }
 
+       rcu_read_lock();
+
        /*
         * Get stream's channel reference. Needed when adding the stream to the
         * global hash table.
@@ -404,19 +503,44 @@ struct lttng_consumer_stream *consumer_allocate_stream(
        stream->gid = gid;
        stream->net_seq_idx = net_index;
        stream->metadata_flag = metadata_flag;
+       stream->session_id = session_id;
        strncpy(stream->path_name, path_name, sizeof(stream->path_name));
        stream->path_name[sizeof(stream->path_name) - 1] = '\0';
-       lttng_ht_node_init_ulong(&stream->waitfd_node, stream->wait_fd);
-       lttng_ht_node_init_ulong(&stream->node, stream->key);
+       pthread_mutex_init(&stream->lock, NULL);
+
+       /*
+        * Index differently the metadata node because the thread is using an
+        * internal hash table to match streams in the metadata_ht to the epoll set
+        * file descriptor.
+        */
+       if (metadata_flag) {
+               lttng_ht_node_init_ulong(&stream->node, stream->wait_fd);
+       } else {
+               lttng_ht_node_init_ulong(&stream->node, stream->key);
+       }
+
+       /* Init session id node with the stream session id */
+       lttng_ht_node_init_ulong(&stream->node_session_id, stream->session_id);
+
+       /*
+        * The cpu number is needed before using any ustctl_* actions. Ignored for
+        * the kernel so the value does not matter.
+        */
+       pthread_mutex_lock(&consumer_data.lock);
+       stream->cpu = stream->chan->cpucount++;
+       pthread_mutex_unlock(&consumer_data.lock);
 
        DBG3("Allocated stream %s (key %d, shm_fd %d, wait_fd %d, mmap_len %llu,"
-                       " out_fd %d, net_seq_idx %d)", stream->path_name, stream->key,
-                       stream->shm_fd, stream->wait_fd,
+                       " out_fd %d, net_seq_idx %d, session_id %" PRIu64,
+                       stream->path_name, stream->key, stream->shm_fd, stream->wait_fd,
                        (unsigned long long) stream->mmap_len, stream->out_fd,
-                       stream->net_seq_idx);
+                       stream->net_seq_idx, stream->session_id);
+
+       rcu_read_unlock();
        return stream;
 
 error:
+       rcu_read_unlock();
        free(stream);
 end:
        return NULL;
@@ -425,41 +549,32 @@ end:
 /*
  * Add a stream to the global list protected by a mutex.
  */
-int consumer_add_stream(struct lttng_consumer_stream *stream)
+static int consumer_add_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
 {
        int ret = 0;
        struct consumer_relayd_sock_pair *relayd;
 
        assert(stream);
+       assert(ht);
 
        DBG3("Adding consumer stream %d", stream->key);
 
        pthread_mutex_lock(&consumer_data.lock);
+       pthread_mutex_lock(&stream->lock);
        rcu_read_lock();
 
-       switch (consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               stream->cpu = stream->chan->cpucount++;
-               ret = lttng_ustconsumer_add_stream(stream);
-               if (ret) {
-                       ret = -EINVAL;
-                       goto error;
-               }
+       /* Steal stream identifier to avoid having streams with the same key */
+       consumer_steal_stream_key(stream->key, ht);
 
-               /* Steal stream identifier only for UST */
-               consumer_steal_stream_key(stream->key, consumer_data.stream_ht);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               assert(0);
-               ret = -ENOSYS;
-               goto error;
-       }
+       lttng_ht_add_unique_ulong(ht, &stream->node);
 
-       lttng_ht_add_unique_ulong(consumer_data.stream_ht, &stream->node);
+       /*
+        * Add stream to the stream_list_ht of the consumer data. No need to steal
+        * the key since the HT does not use it and we allow to add redundant keys
+        * into this table.
+        */
+       lttng_ht_add_ulong(consumer_data.stream_list_ht, &stream->node_session_id);
 
        /* Check and cleanup relayd */
        relayd = consumer_find_relayd(stream->net_seq_idx);
@@ -485,8 +600,8 @@ int consumer_add_stream(struct lttng_consumer_stream *stream)
        consumer_data.stream_count++;
        consumer_data.need_update = 1;
 
-error:
        rcu_read_unlock();
+       pthread_mutex_unlock(&stream->lock);
        pthread_mutex_unlock(&consumer_data.lock);
 
        return ret;
@@ -629,23 +744,6 @@ error:
        return outfd;
 }
 
-/*
- * Update a stream according to what we just received.
- */
-void consumer_change_stream_state(int stream_key,
-               enum lttng_consumer_stream_state state)
-{
-       struct lttng_consumer_stream *stream;
-
-       pthread_mutex_lock(&consumer_data.lock);
-       stream = consumer_find_stream(stream_key, consumer_data.stream_ht);
-       if (stream) {
-               stream->state = state;
-       }
-       consumer_data.need_update = 1;
-       pthread_mutex_unlock(&consumer_data.lock);
-}
-
 static
 void consumer_free_channel(struct rcu_head *head)
 {
@@ -798,9 +896,9 @@ end:
  *
  * Returns the number of fds in the structures.
  */
-int consumer_update_poll_array(
+static int consumer_update_poll_array(
                struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
-               struct lttng_consumer_stream **local_stream)
+               struct lttng_consumer_stream **local_stream, struct lttng_ht *ht)
 {
        int i = 0;
        struct lttng_ht_iter iter;
@@ -808,9 +906,18 @@ int consumer_update_poll_array(
 
        DBG("Updating poll fd array");
        rcu_read_lock();
-       cds_lfht_for_each_entry(consumer_data.stream_ht->ht, &iter.iter, stream,
-                       node.node) {
-               if (stream->state != LTTNG_CONSUMER_ACTIVE_STREAM) {
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+               /*
+                * Only active streams with an active end point can be added to the
+                * poll set and local stream storage of the thread.
+                *
+                * There is a potential race here for endpoint_status to be updated
+                * just after the check. However, this is OK since the stream(s) will
+                * be deleted once the thread is notified that the end point state has
+                * changed where this function will be called back again.
+                */
+               if (stream->state != LTTNG_CONSUMER_ACTIVE_STREAM ||
+                               stream->endpoint_status == CONSUMER_ENDPOINT_INACTIVE) {
                        continue;
                }
                DBG("Active FD %d", stream->wait_fd);
@@ -822,10 +929,10 @@ int consumer_update_poll_array(
        rcu_read_unlock();
 
        /*
-        * Insert the consumer_poll_pipe at the end of the array and don't
+        * Insert the consumer_data_pipe at the end of the array and don't
         * increment i so nb_fd is the number of real FD.
         */
-       (*pollfd)[i].fd = ctx->consumer_poll_pipe[0];
+       (*pollfd)[i].fd = ctx->consumer_data_pipe[0];
        (*pollfd)[i].events = POLLIN | POLLPRI;
        return i;
 }
@@ -904,17 +1011,6 @@ void lttng_consumer_cleanup(void)
 
        rcu_read_lock();
 
-       /*
-        * close all outfd. Called when there are no more threads running (after
-        * joining on the threads), no need to protect list iteration with mutex.
-        */
-       cds_lfht_for_each_entry(consumer_data.stream_ht->ht, &iter.iter, node,
-                       node) {
-               struct lttng_consumer_stream *stream =
-                       caa_container_of(node, struct lttng_consumer_stream, node);
-               consumer_del_stream(stream, consumer_data.stream_ht);
-       }
-
        cds_lfht_for_each_entry(consumer_data.channel_ht->ht, &iter.iter, node,
                        node) {
                struct lttng_consumer_channel *channel =
@@ -924,7 +1020,6 @@ void lttng_consumer_cleanup(void)
 
        rcu_read_unlock();
 
-       lttng_ht_destroy(consumer_data.stream_ht);
        lttng_ht_destroy(consumer_data.channel_ht);
 }
 
@@ -941,6 +1036,8 @@ void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
        if (ret < 0) {
                PERROR("write consumer quit");
        }
+
+       DBG("Consumer flag that it should quit");
 }
 
 void lttng_consumer_sync_trace_file(struct lttng_consumer_stream *stream,
@@ -1022,21 +1119,21 @@ struct lttng_consumer_local_data *lttng_consumer_create(
        ctx->on_recv_stream = recv_stream;
        ctx->on_update_stream = update_stream;
 
-       ret = pipe(ctx->consumer_poll_pipe);
+       ret = pipe(ctx->consumer_data_pipe);
        if (ret < 0) {
                PERROR("Error creating poll pipe");
                goto error_poll_pipe;
        }
 
        /* set read end of the pipe to non-blocking */
-       ret = fcntl(ctx->consumer_poll_pipe[0], F_SETFL, O_NONBLOCK);
+       ret = fcntl(ctx->consumer_data_pipe[0], F_SETFL, O_NONBLOCK);
        if (ret < 0) {
                PERROR("fcntl O_NONBLOCK");
                goto error_poll_fcntl;
        }
 
        /* set write end of the pipe to non-blocking */
-       ret = fcntl(ctx->consumer_poll_pipe[1], F_SETFL, O_NONBLOCK);
+       ret = fcntl(ctx->consumer_data_pipe[1], F_SETFL, O_NONBLOCK);
        if (ret < 0) {
                PERROR("fcntl O_NONBLOCK");
                goto error_poll_fcntl;
@@ -1084,7 +1181,7 @@ error_quit_pipe:
        for (i = 0; i < 2; i++) {
                int err;
 
-               err = close(ctx->consumer_poll_pipe[i]);
+               err = close(ctx->consumer_data_pipe[i]);
                if (err) {
                        PERROR("close");
                }
@@ -1102,6 +1199,8 @@ void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx)
 {
        int ret;
 
+       DBG("Consumer destroying it. Closing everything.");
+
        ret = close(ctx->consumer_error_socket);
        if (ret) {
                PERROR("close");
@@ -1114,11 +1213,11 @@ void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx)
        if (ret) {
                PERROR("close");
        }
-       ret = close(ctx->consumer_poll_pipe[0]);
+       ret = close(ctx->consumer_data_pipe[0]);
        if (ret) {
                PERROR("close");
        }
-       ret = close(ctx->consumer_poll_pipe[1]);
+       ret = close(ctx->consumer_data_pipe[1]);
        if (ret) {
                PERROR("close");
        }
@@ -1168,6 +1267,8 @@ end:
  * core function for writing trace buffers to either the local filesystem or
  * the network.
  *
+ * It must be called with the stream lock held.
+ *
  * Careful review MUST be put if any changes occur!
  *
  * Returns the number of bytes written
@@ -1183,6 +1284,7 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
        /* Default is on the disk */
        int outfd = stream->out_fd;
        struct consumer_relayd_sock_pair *relayd = NULL;
+       unsigned int relayd_hang_up = 0;
 
        /* RCU lock for the relayd pointer */
        rcu_read_lock();
@@ -1240,11 +1342,22 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                                ret = write_relayd_metadata_id(outfd, stream, relayd, padding);
                                if (ret < 0) {
                                        written = ret;
+                                       /* Socket operation failed. We consider the relayd dead */
+                                       if (ret == -EPIPE || ret == -EINVAL) {
+                                               relayd_hang_up = 1;
+                                               goto write_error;
+                                       }
                                        goto end;
                                }
                        }
+               } else {
+                       /* Socket operation failed. We consider the relayd dead */
+                       if (ret == -EPIPE || ret == -EINVAL) {
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
+                       /* Else, use the default set before which is the filesystem. */
                }
-               /* Else, use the default set before which is the filesystem. */
        } else {
                /* No streaming, we have to set the len with the full padding */
                len += padding;
@@ -1260,6 +1373,11 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                        if (written == 0) {
                                written = ret;
                        }
+                       /* Socket operation failed. We consider the relayd dead */
+                       if (errno == EPIPE || errno == EINVAL) {
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
                        goto end;
                } else if (ret > len) {
                        PERROR("Error in file write (ret %zd > len %lu)", ret, len);
@@ -1281,6 +1399,15 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
        }
        lttng_consumer_sync_trace_file(stream, orig_offset);
 
+write_error:
+       /*
+        * This is a special case that the relayd has closed its socket. Let's
+        * cleanup the relayd object and all associated streams.
+        */
+       if (relayd && relayd_hang_up) {
+               cleanup_relayd(relayd, ctx);
+       }
+
 end:
        /* Unlock only if ctrl socket used */
        if (relayd && stream->metadata_flag) {
@@ -1294,6 +1421,8 @@ end:
 /*
  * Splice the data from the ring buffer to the tracefile.
  *
+ * It must be called with the stream lock held.
+ *
  * Returns the number of bytes spliced.
  */
 ssize_t lttng_consumer_on_read_subbuffer_splice(
@@ -1309,6 +1438,7 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
        int outfd = stream->out_fd;
        struct consumer_relayd_sock_pair *relayd = NULL;
        int *splice_pipe;
+       unsigned int relayd_hang_up = 0;
 
        switch (consumer_data.type) {
        case LTTNG_CONSUMER_KERNEL:
@@ -1359,6 +1489,12 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
                                        padding);
                        if (ret < 0) {
                                written = ret;
+                               /* Socket operation failed. We consider the relayd dead */
+                               if (ret == -EBADF) {
+                                       WARN("Remote relayd disconnected. Stopping");
+                                       relayd_hang_up = 1;
+                                       goto write_error;
+                               }
                                goto end;
                        }
 
@@ -1370,7 +1506,12 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
                        /* Use the returned socket. */
                        outfd = ret;
                } else {
-                       ERR("Remote relayd disconnected. Stopping");
+                       /* Socket operation failed. We consider the relayd dead */
+                       if (ret == -EBADF) {
+                               WARN("Remote relayd disconnected. Stopping");
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
                        goto end;
                }
        } else {
@@ -1419,6 +1560,12 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
                        if (written == 0) {
                                written = ret_splice;
                        }
+                       /* Socket operation failed. We consider the relayd dead */
+                       if (errno == EBADF || errno == EPIPE) {
+                               WARN("Remote relayd disconnected. Stopping");
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
                        ret = errno;
                        goto splice_error;
                } else if (ret_splice > len) {
@@ -1446,12 +1593,20 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
 
        goto end;
 
+write_error:
+       /*
+        * This is a special case that the relayd has closed its socket. Let's
+        * cleanup the relayd object and all associated streams.
+        */
+       if (relayd && relayd_hang_up) {
+               cleanup_relayd(relayd, ctx);
+               /* Skip splice error so the consumer does not fail */
+               goto end;
+       }
+
 splice_error:
        /* send the appropriate error description to sessiond */
        switch (ret) {
-       case EBADF:
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_EBADF);
-               break;
        case EINVAL:
                lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_EINVAL);
                break;
@@ -1533,6 +1688,33 @@ int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        }
 }
 
+/*
+ * Iterate over all streams of the hashtable and free them properly.
+ *
+ * WARNING: *MUST* be used with data stream only.
+ */
+static void destroy_data_stream_ht(struct lttng_ht *ht)
+{
+       int ret;
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       if (ht == NULL) {
+               return;
+       }
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+               ret = lttng_ht_del(ht, &iter);
+               assert(!ret);
+
+               call_rcu(&stream->node.head, consumer_free_stream);
+       }
+       rcu_read_unlock();
+
+       lttng_ht_destroy(ht);
+}
+
 /*
  * Iterate over all streams of the hashtable and free them properly.
  *
@@ -1549,11 +1731,11 @@ static void destroy_stream_ht(struct lttng_ht *ht)
        }
 
        rcu_read_lock();
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, waitfd_node.node) {
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
                ret = lttng_ht_del(ht, &iter);
                assert(!ret);
 
-               call_rcu(&stream->waitfd_node.head, consumer_free_metadata_stream);
+               call_rcu(&stream->node.head, consumer_free_stream);
        }
        rcu_read_unlock();
 
@@ -1585,13 +1767,9 @@ void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
                goto free_stream;
        }
 
-       rcu_read_lock();
-       iter.iter.node = &stream->waitfd_node.node;
-       ret = lttng_ht_del(ht, &iter);
-       assert(!ret);
-       rcu_read_unlock();
-
        pthread_mutex_lock(&consumer_data.lock);
+       pthread_mutex_lock(&stream->lock);
+
        switch (consumer_data.type) {
        case LTTNG_CONSUMER_KERNEL:
                if (stream->mmap_base != NULL) {
@@ -1611,6 +1789,17 @@ void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
                goto end;
        }
 
+       rcu_read_lock();
+       iter.iter.node = &stream->node.node;
+       ret = lttng_ht_del(ht, &iter);
+       assert(!ret);
+
+       /* Remove node session id from the consumer_data stream ht */
+       iter.iter.node = &stream->node_session_id.node;
+       ret = lttng_ht_del(consumer_data.stream_list_ht, &iter);
+       assert(!ret);
+       rcu_read_unlock();
+
        if (stream->out_fd >= 0) {
                ret = close(stream->out_fd);
                if (ret) {
@@ -1670,6 +1859,7 @@ void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
        }
 
 end:
+       pthread_mutex_unlock(&stream->lock);
        pthread_mutex_unlock(&consumer_data.lock);
 
        if (free_chan) {
@@ -1677,7 +1867,7 @@ end:
        }
 
 free_stream:
-       call_rcu(&stream->waitfd_node.head, consumer_free_metadata_stream);
+       call_rcu(&stream->node.head, consumer_free_stream);
 }
 
 /*
@@ -1689,6 +1879,8 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
 {
        int ret = 0;
        struct consumer_relayd_sock_pair *relayd;
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_ulong *node;
 
        assert(stream);
        assert(ht);
@@ -1696,27 +1888,7 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
        DBG3("Adding metadata stream %d to hash table", stream->wait_fd);
 
        pthread_mutex_lock(&consumer_data.lock);
-
-       switch (consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               ret = lttng_ustconsumer_add_stream(stream);
-               if (ret) {
-                       ret = -EINVAL;
-                       goto error;
-               }
-
-               /* Steal stream identifier only for UST */
-               consumer_steal_stream_key(stream->wait_fd, ht);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               assert(0);
-               ret = -ENOSYS;
-               goto error;
-       }
+       pthread_mutex_lock(&stream->lock);
 
        /*
         * From here, refcounts are updated so be _careful_ when returning an error
@@ -1724,6 +1896,15 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
         */
 
        rcu_read_lock();
+
+       /*
+        * Lookup the stream just to make sure it does not exist in our internal
+        * state. This should NEVER happen.
+        */
+       lttng_ht_lookup(ht, (void *)((unsigned long) stream->wait_fd), &iter);
+       node = lttng_ht_iter_get_node_ulong(&iter);
+       assert(!node);
+
        /* Find relayd and, if one is found, increment refcount. */
        relayd = consumer_find_relayd(stream->net_seq_idx);
        if (relayd != NULL) {
@@ -1744,14 +1925,75 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
                uatomic_dec(&stream->chan->nb_init_streams);
        }
 
-       lttng_ht_add_unique_ulong(ht, &stream->waitfd_node);
+       lttng_ht_add_unique_ulong(ht, &stream->node);
+
+       /*
+        * Add stream to the stream_list_ht of the consumer data. No need to steal
+        * the key since the HT does not use it and we allow to add redundant keys
+        * into this table.
+        */
+       lttng_ht_add_ulong(consumer_data.stream_list_ht, &stream->node_session_id);
+
        rcu_read_unlock();
 
-error:
+       pthread_mutex_unlock(&stream->lock);
        pthread_mutex_unlock(&consumer_data.lock);
        return ret;
 }
 
+/*
+ * Delete data stream that are flagged for deletion (endpoint_status).
+ */
+static void validate_endpoint_status_data_stream(void)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer delete flagged data stream");
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
+               /* Validate delete flag of the stream */
+               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
+                       continue;
+               }
+               /* Delete it right now */
+               consumer_del_stream(stream, data_ht);
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Delete metadata stream that are flagged for deletion (endpoint_status).
+ */
+static void validate_endpoint_status_metadata_stream(
+               struct lttng_poll_event *pollset)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer delete flagged metadata stream");
+
+       assert(pollset);
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
+               /* Validate delete flag of the stream */
+               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
+                       continue;
+               }
+               /*
+                * Remove from pollset so the metadata thread can continue without
+                * blocking on a deleted stream.
+                */
+               lttng_poll_del(pollset, stream->wait_fd);
+
+               /* Delete it right now */
+               consumer_del_metadata_stream(stream, metadata_ht);
+       }
+       rcu_read_unlock();
+}
+
 /*
  * Thread polls on metadata file descriptor and write them on disk or on the
  * network.
@@ -1763,7 +2005,6 @@ void *consumer_thread_metadata_poll(void *data)
        struct lttng_consumer_stream *stream = NULL;
        struct lttng_ht_iter iter;
        struct lttng_ht_node_ulong *node;
-       struct lttng_ht *metadata_ht = NULL;
        struct lttng_poll_event events;
        struct lttng_consumer_local_data *ctx = data;
        ssize_t len;
@@ -1772,11 +2013,6 @@ void *consumer_thread_metadata_poll(void *data)
 
        DBG("Thread metadata poll started");
 
-       metadata_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
-       if (metadata_ht == NULL) {
-               goto end;
-       }
-
        /* Size is set to 1 for the consumer_metadata pipe */
        ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
        if (ret < 0) {
@@ -1832,7 +2068,10 @@ restart:
                                         * since their might be data to consume.
                                         */
                                        lttng_poll_del(&events, ctx->consumer_metadata_pipe[0]);
-                                       close(ctx->consumer_metadata_pipe[0]);
+                                       ret = close(ctx->consumer_metadata_pipe[0]);
+                                       if (ret < 0) {
+                                               PERROR("close metadata pipe");
+                                       }
                                        continue;
                                } else if (revents & LPOLLIN) {
                                        do {
@@ -1849,6 +2088,13 @@ restart:
                                                continue;
                                        }
 
+                                       /* A NULL stream means that the state has changed. */
+                                       if (stream == NULL) {
+                                               /* Check for deleted streams. */
+                                               validate_endpoint_status_metadata_stream(&events);
+                                               continue;
+                                       }
+
                                        DBG("Adding metadata stream %d to poll set",
                                                        stream->wait_fd);
 
@@ -1876,7 +2122,7 @@ restart:
                        assert(node);
 
                        stream = caa_container_of(node, struct lttng_consumer_stream,
-                                       waitfd_node);
+                                       node);
 
                        /* Check for error event */
                        if (revents & (LPOLLERR | LPOLLHUP)) {
@@ -1913,8 +2159,9 @@ restart:
                                len = ctx->on_buffer_ready(stream, ctx);
                                /* It's ok to have an unavailable sub-buffer */
                                if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       rcu_read_unlock();
-                                       goto end;
+                                       /* Clean up stream from consumer and free it. */
+                                       lttng_poll_del(&events, stream->wait_fd);
+                                       consumer_del_metadata_stream(stream, metadata_ht);
                                } else if (len > 0) {
                                        stream->data_read = 1;
                                }
@@ -1947,7 +2194,7 @@ void *consumer_thread_data_poll(void *data)
        int num_rdy, num_hup, high_prio, ret, i;
        struct pollfd *pollfd = NULL;
        /* local view of the streams */
-       struct lttng_consumer_stream **local_stream = NULL;
+       struct lttng_consumer_stream **local_stream = NULL, *new_stream = NULL;
        /* local view of consumer_data.fds_count */
        int nb_fd = 0;
        struct lttng_consumer_local_data *ctx = data;
@@ -1955,6 +2202,11 @@ void *consumer_thread_data_poll(void *data)
 
        rcu_register_thread();
 
+       data_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+       if (data_ht == NULL) {
+               goto end;
+       }
+
        local_stream = zmalloc(sizeof(struct lttng_consumer_stream));
 
        while (1) {
@@ -1976,7 +2228,7 @@ void *consumer_thread_data_poll(void *data)
                                local_stream = NULL;
                        }
 
-                       /* allocate for all fds + 1 for the consumer_poll_pipe */
+                       /* allocate for all fds + 1 for the consumer_data_pipe */
                        pollfd = zmalloc((consumer_data.stream_count + 1) * sizeof(struct pollfd));
                        if (pollfd == NULL) {
                                PERROR("pollfd malloc");
@@ -1984,7 +2236,7 @@ void *consumer_thread_data_poll(void *data)
                                goto end;
                        }
 
-                       /* allocate for all fds + 1 for the consumer_poll_pipe */
+                       /* allocate for all fds + 1 for the consumer_data_pipe */
                        local_stream = zmalloc((consumer_data.stream_count + 1) *
                                        sizeof(struct lttng_consumer_stream));
                        if (local_stream == NULL) {
@@ -1992,7 +2244,8 @@ void *consumer_thread_data_poll(void *data)
                                pthread_mutex_unlock(&consumer_data.lock);
                                goto end;
                        }
-                       ret = consumer_update_poll_array(ctx, &pollfd, local_stream);
+                       ret = consumer_update_poll_array(ctx, &pollfd, local_stream,
+                                       data_ht);
                        if (ret < 0) {
                                ERR("Error in allocating pollfd or local_outfds");
                                lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
@@ -2011,7 +2264,7 @@ void *consumer_thread_data_poll(void *data)
                /* poll on the array of fds */
        restart:
                DBG("polling on %d fd", nb_fd + 1);
-               num_rdy = poll(pollfd, nb_fd + 1, consumer_poll_timeout);
+               num_rdy = poll(pollfd, nb_fd + 1, -1);
                DBG("poll num_rdy : %d", num_rdy);
                if (num_rdy == -1) {
                        /*
@@ -2029,31 +2282,59 @@ void *consumer_thread_data_poll(void *data)
                }
 
                /*
-                * If the consumer_poll_pipe triggered poll go directly to the
+                * If the consumer_data_pipe triggered poll go directly to the
                 * beginning of the loop to update the array. We want to prioritize
                 * array update over low-priority reads.
                 */
                if (pollfd[nb_fd].revents & (POLLIN | POLLPRI)) {
                        size_t pipe_readlen;
-                       char tmp;
 
-                       DBG("consumer_poll_pipe wake up");
+                       DBG("consumer_data_pipe wake up");
                        /* Consume 1 byte of pipe data */
                        do {
-                               pipe_readlen = read(ctx->consumer_poll_pipe[0], &tmp, 1);
+                               pipe_readlen = read(ctx->consumer_data_pipe[0], &new_stream,
+                                               sizeof(new_stream));
                        } while (pipe_readlen == -1 && errno == EINTR);
+
+                       /*
+                        * If the stream is NULL, just ignore it. It's also possible that
+                        * the sessiond poll thread changed the consumer_quit state and is
+                        * waking us up to test it.
+                        */
+                       if (new_stream == NULL) {
+                               validate_endpoint_status_data_stream();
+                               continue;
+                       }
+
+                       ret = consumer_add_stream(new_stream, data_ht);
+                       if (ret) {
+                               ERR("Consumer add stream %d failed. Continuing",
+                                               new_stream->key);
+                               /*
+                                * At this point, if the add_stream fails, it is not in the
+                                * hash table thus passing the NULL value here.
+                                */
+                               consumer_del_stream(new_stream, NULL);
+                       }
+
+                       /* Continue to update the local streams and handle prio ones */
                        continue;
                }
 
                /* Take care of high priority channels first. */
                for (i = 0; i < nb_fd; i++) {
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
                        if (pollfd[i].revents & POLLPRI) {
                                DBG("Urgent read on fd %d", pollfd[i].fd);
                                high_prio = 1;
                                len = ctx->on_buffer_ready(local_stream[i], ctx);
                                /* it's ok to have an unavailable sub-buffer */
                                if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       goto end;
+                                       /* Clean the stream and free it. */
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
                                } else if (len > 0) {
                                        local_stream[i]->data_read = 1;
                                }
@@ -2070,13 +2351,18 @@ void *consumer_thread_data_poll(void *data)
 
                /* Take care of low priority channels. */
                for (i = 0; i < nb_fd; i++) {
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
                        if ((pollfd[i].revents & POLLIN) ||
                                        local_stream[i]->hangup_flush_done) {
                                DBG("Normal read on fd %d", pollfd[i].fd);
                                len = ctx->on_buffer_ready(local_stream[i], ctx);
                                /* it's ok to have an unavailable sub-buffer */
                                if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       goto end;
+                                       /* Clean the stream and free it. */
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
                                } else if (len > 0) {
                                        local_stream[i]->data_read = 1;
                                }
@@ -2085,12 +2371,15 @@ void *consumer_thread_data_poll(void *data)
 
                /* Handle hangup and errors */
                for (i = 0; i < nb_fd; i++) {
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
                        if (!local_stream[i]->hangup_flush_done
                                        && (pollfd[i].revents & (POLLHUP | POLLERR | POLLNVAL))
                                        && (consumer_data.type == LTTNG_CONSUMER32_UST
                                                || consumer_data.type == LTTNG_CONSUMER64_UST)) {
                                DBG("fd %d is hup|err|nval. Attempting flush and read.",
-                                       pollfd[i].fd);
+                                               pollfd[i].fd);
                                lttng_ustconsumer_on_stream_hangup(local_stream[i]);
                                /* Attempt read again, for the data we just flushed. */
                                local_stream[i]->data_read = 1;
@@ -2103,26 +2392,28 @@ void *consumer_thread_data_poll(void *data)
                        if ((pollfd[i].revents & POLLHUP)) {
                                DBG("Polling fd %d tells it has hung up.", pollfd[i].fd);
                                if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i],
-                                                       consumer_data.stream_ht);
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
                                        num_hup++;
                                }
                        } else if (pollfd[i].revents & POLLERR) {
                                ERR("Error returned in polling fd %d.", pollfd[i].fd);
                                if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i],
-                                                       consumer_data.stream_ht);
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
                                        num_hup++;
                                }
                        } else if (pollfd[i].revents & POLLNVAL) {
                                ERR("Polling fd %d tells fd is not open.", pollfd[i].fd);
                                if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i],
-                                                       consumer_data.stream_ht);
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
                                        num_hup++;
                                }
                        }
-                       local_stream[i]->data_read = 0;
+                       if (local_stream[i] != NULL) {
+                               local_stream[i]->data_read = 0;
+                       }
                }
        }
 end:
@@ -2144,7 +2435,14 @@ end:
         * only tracked fd in the poll set. The thread will take care of closing
         * the read side.
         */
-       close(ctx->consumer_metadata_pipe[1]);
+       ret = close(ctx->consumer_metadata_pipe[1]);
+       if (ret < 0) {
+               PERROR("close data pipe");
+       }
+
+       if (data_ht) {
+               destroy_data_stream_ht(data_ht);
+       }
 
        rcu_unregister_thread();
        return NULL;
@@ -2156,7 +2454,7 @@ end:
  */
 void *consumer_thread_sessiond_poll(void *data)
 {
-       int sock, client_socket, ret;
+       int sock = -1, client_socket, ret;
        /*
         * structure to poll for incoming data on communication socket avoids
         * making blocking sockets.
@@ -2216,6 +2514,13 @@ void *consumer_thread_sessiond_poll(void *data)
                goto end;
        }
 
+       /* This socket is not useful anymore. */
+       ret = close(client_socket);
+       if (ret < 0) {
+               PERROR("close client_socket");
+       }
+       client_socket = -1;
+
        /* update the polling structure to poll on the established socket */
        consumer_sockpoll[1].fd = sock;
        consumer_sockpoll[1].events = POLLIN | POLLPRI;
@@ -2254,26 +2559,25 @@ end:
        consumer_quit = 1;
 
        /*
-        * 2s of grace period, if no polling events occur during
-        * this period, the polling thread will exit even if there
-        * are still open FDs (should not happen, but safety mechanism).
+        * Notify the data poll thread to poll back again and test the
+        * consumer_quit state that we just set so to quit gracefully.
         */
-       consumer_poll_timeout = LTTNG_CONSUMER_POLL_TIMEOUT;
+       notify_thread_pipe(ctx->consumer_data_pipe[1]);
+
+       /* Cleaning up possibly open sockets. */
+       if (sock >= 0) {
+               ret = close(sock);
+               if (ret < 0) {
+                       PERROR("close sock sessiond poll");
+               }
+       }
+       if (client_socket >= 0) {
+               ret = close(sock);
+               if (ret < 0) {
+                       PERROR("close client_socket sessiond poll");
+               }
+       }
 
-       /*
-        * Wake-up the other end by writing a null byte in the pipe
-        * (non-blocking). Important note: Because writing into the
-        * pipe is non-blocking (and therefore we allow dropping wakeup
-        * data, as long as there is wakeup data present in the pipe
-        * buffer to wake up the other end), the other end should
-        * perform the following sequence for waiting:
-        * 1) empty the pipe (reads).
-        * 2) perform update operation.
-        * 3) wait on the pipe (poll).
-        */
-       do {
-               ret = write(ctx->consumer_poll_pipe[1], "", 1);
-       } while (ret < 0 && errno == EINTR);
        rcu_unregister_thread();
        return NULL;
 }
@@ -2281,17 +2585,27 @@ end:
 ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
                struct lttng_consumer_local_data *ctx)
 {
+       ssize_t ret;
+
+       pthread_mutex_lock(&stream->lock);
+
        switch (consumer_data.type) {
        case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_read_subbuffer(stream, ctx);
+               ret = lttng_kconsumer_read_subbuffer(stream, ctx);
+               break;
        case LTTNG_CONSUMER32_UST:
        case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_read_subbuffer(stream, ctx);
+               ret = lttng_ustconsumer_read_subbuffer(stream, ctx);
+               break;
        default:
                ERR("Unknown consumer_data type");
                assert(0);
-               return -ENOSYS;
+               ret = -ENOSYS;
+               break;
        }
+
+       pthread_mutex_unlock(&stream->lock);
+       return ret;
 }
 
 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream)
@@ -2314,9 +2628,14 @@ int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream)
  */
 void lttng_consumer_init(void)
 {
-       consumer_data.stream_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
        consumer_data.channel_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
        consumer_data.relayd_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+       consumer_data.stream_list_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+
+       metadata_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+       assert(metadata_ht);
+       data_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+       assert(data_ht);
 }
 
 /*
@@ -2329,7 +2648,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                struct lttng_consumer_local_data *ctx, int sock,
                struct pollfd *consumer_sockpoll, struct lttcomm_sock *relayd_sock)
 {
-       int fd, ret = -1;
+       int fd = -1, ret = -1;
        struct consumer_relayd_sock_pair *relayd;
 
        DBG("Consumer adding relayd socket (idx: %d)", net_seq_idx);
@@ -2356,6 +2675,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
        if (ret != sizeof(fd)) {
                lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
                ret = -1;
+               fd = -1;        /* Just in case it gets set with an invalid value. */
                goto error;
        }
 
@@ -2365,13 +2685,17 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                /* Copy received lttcomm socket */
                lttcomm_copy_sock(&relayd->control_sock, relayd_sock);
                ret = lttcomm_create_sock(&relayd->control_sock);
+               /* Immediately try to close the created socket if valid. */
+               if (relayd->control_sock.fd >= 0) {
+                       if (close(relayd->control_sock.fd)) {
+                               PERROR("close relayd control socket");
+                       }
+               }
+               /* Handle create_sock error. */
                if (ret < 0) {
                        goto error;
                }
 
-               /* Close the created socket fd which is useless */
-               close(relayd->control_sock.fd);
-
                /* Assign new file descriptor */
                relayd->control_sock.fd = fd;
                break;
@@ -2379,13 +2703,17 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                /* Copy received lttcomm socket */
                lttcomm_copy_sock(&relayd->data_sock, relayd_sock);
                ret = lttcomm_create_sock(&relayd->data_sock);
+               /* Immediately try to close the created socket if valid. */
+               if (relayd->data_sock.fd >= 0) {
+                       if (close(relayd->data_sock.fd)) {
+                               PERROR("close relayd data socket");
+                       }
+               }
+               /* Handle create_sock error. */
                if (ret < 0) {
                        goto error;
                }
 
-               /* Close the created socket fd which is useless */
-               close(relayd->data_sock.fd);
-
                /* Assign new file descriptor */
                relayd->data_sock.fd = fd;
                break;
@@ -2405,8 +2733,153 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
        add_relayd(relayd);
 
        /* All good! */
-       ret = 0;
+       return 0;
 
 error:
+       /* Close received socket if valid. */
+       if (fd >= 0) {
+               if (close(fd)) {
+                       PERROR("close received socket");
+               }
+       }
        return ret;
 }
+
+/*
+ * Try to lock the stream mutex.
+ *
+ * On success, 1 is returned else 0 indicating that the mutex is NOT lock.
+ */
+static int stream_try_lock(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       assert(stream);
+
+       /*
+        * Try to lock the stream mutex. On failure, we know that the stream is
+        * being used else where hence there is data still being extracted.
+        */
+       ret = pthread_mutex_trylock(&stream->lock);
+       if (ret) {
+               /* For both EBUSY and EINVAL error, the mutex is NOT locked. */
+               ret = 0;
+               goto end;
+       }
+
+       ret = 1;
+
+end:
+       return ret;
+}
+
+/*
+ * Check if for a given session id there is still data needed to be extract
+ * from the buffers.
+ *
+ * Return 1 if data is pending or else 0 meaning ready to be read.
+ */
+int consumer_data_pending(uint64_t id)
+{
+       int ret;
+       struct lttng_ht_iter iter;
+       struct lttng_ht *ht;
+       struct lttng_consumer_stream *stream;
+       struct consumer_relayd_sock_pair *relayd;
+       int (*data_pending)(struct lttng_consumer_stream *);
+
+       DBG("Consumer data pending command on session id %" PRIu64, id);
+
+       rcu_read_lock();
+       pthread_mutex_lock(&consumer_data.lock);
+
+       switch (consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               data_pending = lttng_kconsumer_data_pending;
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               data_pending = lttng_ustconsumer_data_pending;
+               break;
+       default:
+               ERR("Unknown consumer data type");
+               assert(0);
+       }
+
+       /* Ease our life a bit */
+       ht = consumer_data.stream_list_ht;
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct((void *)((unsigned long) id), lttng_ht_seed),
+                       ht->match_fct, (void *)((unsigned long) id),
+                       &iter.iter, stream, node_session_id.node) {
+               /* If this call fails, the stream is being used hence data pending. */
+               ret = stream_try_lock(stream);
+               if (!ret) {
+                       goto data_not_pending;
+               }
+
+               /*
+                * A removed node from the hash table indicates that the stream has
+                * been deleted thus having a guarantee that the buffers are closed
+                * on the consumer side. However, data can still be transmitted
+                * over the network so don't skip the relayd check.
+                */
+               ret = cds_lfht_is_node_deleted(&stream->node.node);
+               if (!ret) {
+                       /* Check the stream if there is data in the buffers. */
+                       ret = data_pending(stream);
+                       if (ret == 1) {
+                               pthread_mutex_unlock(&stream->lock);
+                               goto data_not_pending;
+                       }
+               }
+
+               /* Relayd check */
+               if (stream->net_seq_idx != -1) {
+                       relayd = consumer_find_relayd(stream->net_seq_idx);
+                       if (!relayd) {
+                               /*
+                                * At this point, if the relayd object is not available for the
+                                * given stream, it is because the relayd is being cleaned up
+                                * so every stream associated with it (for a session id value)
+                                * are or will be marked for deletion hence no data pending.
+                                */
+                               pthread_mutex_unlock(&stream->lock);
+                               goto data_not_pending;
+                       }
+
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+                       if (stream->metadata_flag) {
+                               ret = relayd_quiescent_control(&relayd->control_sock);
+                       } else {
+                               ret = relayd_data_pending(&relayd->control_sock,
+                                               stream->relayd_stream_id, stream->next_net_seq_num);
+                       }
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+                       if (ret == 1) {
+                               pthread_mutex_unlock(&stream->lock);
+                               goto data_not_pending;
+                       }
+               }
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       /*
+        * Finding _no_ node in the hash table means that the stream(s) have been
+        * removed thus data is guaranteed to be available for analysis from the
+        * trace files. This is *only* true for local consumer and not network
+        * streaming.
+        */
+
+       /* Data is available to be read by a viewer. */
+       pthread_mutex_unlock(&consumer_data.lock);
+       rcu_read_unlock();
+       return 0;
+
+data_not_pending:
+       /* Data is still being extracted from buffers. */
+       pthread_mutex_unlock(&consumer_data.lock);
+       rcu_read_unlock();
+       return 1;
+}
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