Fix: Empty metadata buffer(s) on HUP|ERR
[lttng-tools.git] / src / common / consumer.c
index f093f0cf5caab19bdf0108cc940021711447b43d..8b43257bd134987a3d0811320276010b724579b3 100644 (file)
@@ -62,20 +62,23 @@ volatile int consumer_quit = 0;
  * Find a stream. The consumer_data.lock must be locked during this
  * call.
  */
-static struct lttng_consumer_stream *consumer_find_stream(int key)
+static struct lttng_consumer_stream *consumer_find_stream(int key,
+               struct lttng_ht *ht)
 {
        struct lttng_ht_iter iter;
        struct lttng_ht_node_ulong *node;
        struct lttng_consumer_stream *stream = NULL;
 
+       assert(ht);
+
        /* Negative keys are lookup failures */
-       if (key < 0)
+       if (key < 0) {
                return NULL;
+       }
 
        rcu_read_lock();
 
-       lttng_ht_lookup(consumer_data.stream_ht, (void *)((unsigned long) key),
-                       &iter);
+       lttng_ht_lookup(ht, (void *)((unsigned long) key), &iter);
        node = lttng_ht_iter_get_node_ulong(&iter);
        if (node != NULL) {
                stream = caa_container_of(node, struct lttng_consumer_stream, node);
@@ -86,12 +89,12 @@ static struct lttng_consumer_stream *consumer_find_stream(int key)
        return stream;
 }
 
-static void consumer_steal_stream_key(int key)
+static void consumer_steal_stream_key(int key, struct lttng_ht *ht)
 {
        struct lttng_consumer_stream *stream;
 
        rcu_read_lock();
-       stream = consumer_find_stream(key);
+       stream = consumer_find_stream(key, ht);
        if (stream) {
                stream->key = -1;
                /*
@@ -111,8 +114,9 @@ static struct lttng_consumer_channel *consumer_find_channel(int key)
        struct lttng_consumer_channel *channel = NULL;
 
        /* Negative keys are lookup failures */
-       if (key < 0)
+       if (key < 0) {
                return NULL;
+       }
 
        rcu_read_lock();
 
@@ -157,6 +161,17 @@ 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.
  */
@@ -175,7 +190,7 @@ static void consumer_rcu_free_relayd(struct rcu_head *head)
  *
  * This function MUST be called with the consumer_data lock acquired.
  */
-void consumer_destroy_relayd(struct consumer_relayd_sock_pair *relayd)
+static void destroy_relayd(struct consumer_relayd_sock_pair *relayd)
 {
        int ret;
        struct lttng_ht_iter iter;
@@ -218,7 +233,7 @@ void consumer_flag_relayd_for_destroy(struct consumer_relayd_sock_pair *relayd)
 
        /* Destroy the relayd if refcount is 0 */
        if (uatomic_read(&relayd->refcount) == 0) {
-               consumer_destroy_relayd(relayd);
+               destroy_relayd(relayd);
        }
 }
 
@@ -226,7 +241,8 @@ void consumer_flag_relayd_for_destroy(struct consumer_relayd_sock_pair *relayd)
  * Remove a stream from the global list protected by a mutex. This
  * function is also responsible for freeing its data structures.
  */
-void consumer_del_stream(struct lttng_consumer_stream *stream)
+void consumer_del_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
 {
        int ret;
        struct lttng_ht_iter iter;
@@ -235,6 +251,11 @@ void consumer_del_stream(struct lttng_consumer_stream *stream)
 
        assert(stream);
 
+       if (ht == NULL) {
+               /* Means the stream was allocated but not successfully added */
+               goto free_stream;
+       }
+
        pthread_mutex_lock(&consumer_data.lock);
 
        switch (consumer_data.type) {
@@ -242,7 +263,7 @@ void consumer_del_stream(struct lttng_consumer_stream *stream)
                if (stream->mmap_base != NULL) {
                        ret = munmap(stream->mmap_base, stream->mmap_len);
                        if (ret != 0) {
-                               perror("munmap");
+                               PERROR("munmap");
                        }
                }
                break;
@@ -258,7 +279,7 @@ void consumer_del_stream(struct lttng_consumer_stream *stream)
 
        rcu_read_lock();
        iter.iter.node = &stream->node.node;
-       ret = lttng_ht_del(consumer_data.stream_ht, &iter);
+       ret = lttng_ht_del(ht, &iter);
        assert(!ret);
 
        rcu_read_unlock();
@@ -314,23 +335,27 @@ void consumer_del_stream(struct lttng_consumer_stream *stream)
                /* Both conditions are met, we destroy the relayd. */
                if (uatomic_read(&relayd->refcount) == 0 &&
                                uatomic_read(&relayd->destroy_flag)) {
-                       consumer_destroy_relayd(relayd);
+                       destroy_relayd(relayd);
                }
        }
        rcu_read_unlock();
 
-       if (!--stream->chan->refcount) {
+       uatomic_dec(&stream->chan->refcount);
+       if (!uatomic_read(&stream->chan->refcount)
+                       && !uatomic_read(&stream->chan->nb_init_streams)) {
                free_chan = stream->chan;
        }
 
-
-       call_rcu(&stream->node.head, consumer_free_stream);
 end:
        consumer_data.need_update = 1;
        pthread_mutex_unlock(&consumer_data.lock);
 
-       if (free_chan)
+       if (free_chan) {
                consumer_del_channel(free_chan);
+       }
+
+free_stream:
+       call_rcu(&stream->node.head, consumer_free_stream);
 }
 
 struct lttng_consumer_stream *consumer_allocate_stream(
@@ -343,22 +368,29 @@ struct lttng_consumer_stream *consumer_allocate_stream(
                uid_t uid,
                gid_t gid,
                int net_index,
-               int metadata_flag)
+               int metadata_flag,
+               int *alloc_ret)
 {
        struct lttng_consumer_stream *stream;
-       int ret;
 
        stream = zmalloc(sizeof(*stream));
        if (stream == NULL) {
-               perror("malloc struct lttng_consumer_stream");
+               PERROR("malloc struct lttng_consumer_stream");
+               *alloc_ret = -ENOMEM;
                goto end;
        }
+
+       /*
+        * Get stream's channel reference. Needed when adding the stream to the
+        * global hash table.
+        */
        stream->chan = consumer_find_channel(channel_key);
        if (!stream->chan) {
-               perror("Unable to find channel key");
-               goto end;
+               *alloc_ret = -ENOENT;
+               ERR("Unable to find channel for stream %d", stream_key);
+               goto error;
        }
-       stream->chan->refcount++;
+
        stream->key = stream_key;
        stream->shm_fd = shm_fd;
        stream->wait_fd = wait_fd;
@@ -374,35 +406,20 @@ struct lttng_consumer_stream *consumer_allocate_stream(
        stream->metadata_flag = metadata_flag;
        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->node, stream->key);
        lttng_ht_node_init_ulong(&stream->waitfd_node, stream->wait_fd);
+       lttng_ht_node_init_ulong(&stream->node, stream->key);
 
-       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_allocate_stream(stream);
-               if (ret) {
-                       free(stream);
-                       return NULL;
-               }
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               assert(0);
-               goto end;
-       }
-       DBG("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,
-                       (unsigned long long) stream->mmap_len,
-                       stream->out_fd,
+       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,
+                       (unsigned long long) stream->mmap_len, stream->out_fd,
                        stream->net_seq_idx);
-end:
        return stream;
+
+error:
+       free(stream);
+end:
+       return NULL;
 }
 
 /*
@@ -411,22 +428,35 @@ end:
 int consumer_add_stream(struct lttng_consumer_stream *stream)
 {
        int ret = 0;
-       struct lttng_ht_node_ulong *node;
-       struct lttng_ht_iter iter;
        struct consumer_relayd_sock_pair *relayd;
 
-       pthread_mutex_lock(&consumer_data.lock);
-       /* Steal stream identifier, for UST */
-       consumer_steal_stream_key(stream->key);
+       assert(stream);
 
+       DBG3("Adding consumer stream %d", stream->key);
+
+       pthread_mutex_lock(&consumer_data.lock);
        rcu_read_lock();
-       lttng_ht_lookup(consumer_data.stream_ht,
-                       (void *)((unsigned long) stream->key), &iter);
-       node = lttng_ht_iter_get_node_ulong(&iter);
-       if (node != NULL) {
-               rcu_read_unlock();
-               /* Stream already exist. Ignore the insertion */
-               goto end;
+
+       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 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(consumer_data.stream_ht, &stream->node);
@@ -436,13 +466,27 @@ int consumer_add_stream(struct lttng_consumer_stream *stream)
        if (relayd != NULL) {
                uatomic_inc(&relayd->refcount);
        }
-       rcu_read_unlock();
 
-       /* Update consumer data */
+       /* Update channel refcount once added without error(s). */
+       uatomic_inc(&stream->chan->refcount);
+
+       /*
+        * When nb_init_streams reaches 0, we don't need to trigger any action in
+        * terms of destroying the associated channel, because the action that
+        * causes the count to become 0 also causes a stream to be added. The
+        * channel deletion will thus be triggered by the following removal of this
+        * stream.
+        */
+       if (uatomic_read(&stream->chan->nb_init_streams) > 0) {
+               uatomic_dec(&stream->chan->nb_init_streams);
+       }
+
+       /* Update consumer data once the node is inserted. */
        consumer_data.stream_count++;
        consumer_data.need_update = 1;
 
-end:
+error:
+       rcu_read_unlock();
        pthread_mutex_unlock(&consumer_data.lock);
 
        return ret;
@@ -452,8 +496,7 @@ end:
  * Add relayd socket to global consumer data hashtable. RCU read side lock MUST
  * be acquired before calling this.
  */
-
-int consumer_add_relayd(struct consumer_relayd_sock_pair *relayd)
+static int add_relayd(struct consumer_relayd_sock_pair *relayd)
 {
        int ret = 0;
        struct lttng_ht_node_ulong *node;
@@ -542,7 +585,8 @@ error:
  * Return destination file descriptor or negative value on error.
  */
 static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
-               size_t data_size, struct consumer_relayd_sock_pair *relayd)
+               size_t data_size, unsigned long padding,
+               struct consumer_relayd_sock_pair *relayd)
 {
        int outfd = -1, ret;
        struct lttcomm_relayd_data_hdr data_hdr;
@@ -567,6 +611,7 @@ static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
                /* Set header with stream information */
                data_hdr.stream_id = htobe64(stream->relayd_stream_id);
                data_hdr.data_size = htobe32(data_size);
+               data_hdr.padding_size = htobe32(padding);
                data_hdr.net_seq_num = htobe64(stream->next_net_seq_num++);
                /* Other fields are zeroed previously */
 
@@ -593,7 +638,7 @@ void consumer_change_stream_state(int stream_key,
        struct lttng_consumer_stream *stream;
 
        pthread_mutex_lock(&consumer_data.lock);
-       stream = consumer_find_stream(stream_key);
+       stream = consumer_find_stream(stream_key, consumer_data.stream_ht);
        if (stream) {
                stream->state = state;
        }
@@ -645,7 +690,7 @@ void consumer_del_channel(struct lttng_consumer_channel *channel)
        if (channel->mmap_base != NULL) {
                ret = munmap(channel->mmap_base, channel->mmap_len);
                if (ret != 0) {
-                       perror("munmap");
+                       PERROR("munmap");
                }
        }
        if (channel->wait_fd >= 0 && !channel->wait_fd_is_copy) {
@@ -670,14 +715,15 @@ struct lttng_consumer_channel *consumer_allocate_channel(
                int channel_key,
                int shm_fd, int wait_fd,
                uint64_t mmap_len,
-               uint64_t max_sb_size)
+               uint64_t max_sb_size,
+               unsigned int nb_init_streams)
 {
        struct lttng_consumer_channel *channel;
        int ret;
 
        channel = zmalloc(sizeof(*channel));
        if (channel == NULL) {
-               perror("malloc struct lttng_consumer_channel");
+               PERROR("malloc struct lttng_consumer_channel");
                goto end;
        }
        channel->key = channel_key;
@@ -686,6 +732,7 @@ struct lttng_consumer_channel *consumer_allocate_channel(
        channel->mmap_len = mmap_len;
        channel->max_sb_size = max_sb_size;
        channel->refcount = 0;
+       channel->nb_init_streams = nb_init_streams;
        lttng_ht_node_init_ulong(&channel->node, channel->key);
 
        switch (consumer_data.type) {
@@ -800,7 +847,7 @@ restart:
                if (errno == EINTR) {
                        goto restart;
                }
-               perror("Poll error");
+               PERROR("Poll error");
                goto exit;
        }
        if (consumer_sockpoll[0].revents & (POLLIN | POLLPRI)) {
@@ -865,7 +912,7 @@ void lttng_consumer_cleanup(void)
                        node) {
                struct lttng_consumer_stream *stream =
                        caa_container_of(node, struct lttng_consumer_stream, node);
-               consumer_del_stream(stream);
+               consumer_del_stream(stream, consumer_data.stream_ht);
        }
 
        cds_lfht_for_each_entry(consumer_data.channel_ht->ht, &iter.iter, node,
@@ -892,7 +939,7 @@ void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
                ret = write(ctx->consumer_should_quit[1], "4", 1);
        } while (ret < 0 && errno == EINTR);
        if (ret < 0) {
-               perror("write consumer quit");
+               PERROR("write consumer quit");
        }
 }
 
@@ -964,7 +1011,7 @@ struct lttng_consumer_local_data *lttng_consumer_create(
 
        ctx = zmalloc(sizeof(struct lttng_consumer_local_data));
        if (ctx == NULL) {
-               perror("allocating context");
+               PERROR("allocating context");
                goto error;
        }
 
@@ -977,33 +1024,33 @@ struct lttng_consumer_local_data *lttng_consumer_create(
 
        ret = pipe(ctx->consumer_poll_pipe);
        if (ret < 0) {
-               perror("Error creating poll pipe");
+               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);
        if (ret < 0) {
-               perror("fcntl O_NONBLOCK");
+               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);
        if (ret < 0) {
-               perror("fcntl O_NONBLOCK");
+               PERROR("fcntl O_NONBLOCK");
                goto error_poll_fcntl;
        }
 
        ret = pipe(ctx->consumer_should_quit);
        if (ret < 0) {
-               perror("Error creating recv pipe");
+               PERROR("Error creating recv pipe");
                goto error_quit_pipe;
        }
 
        ret = pipe(ctx->consumer_thread_pipe);
        if (ret < 0) {
-               perror("Error creating thread pipe");
+               PERROR("Error creating thread pipe");
                goto error_thread_pipe;
        }
 
@@ -1094,22 +1141,23 @@ void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx)
  */
 static int write_relayd_metadata_id(int fd,
                struct lttng_consumer_stream *stream,
-               struct consumer_relayd_sock_pair *relayd)
+               struct consumer_relayd_sock_pair *relayd,
+               unsigned long padding)
 {
        int ret;
-       uint64_t metadata_id;
+       struct lttcomm_relayd_metadata_payload hdr;
 
-       metadata_id = htobe64(stream->relayd_stream_id);
+       hdr.stream_id = htobe64(stream->relayd_stream_id);
+       hdr.padding_size = htobe32(padding);
        do {
-               ret = write(fd, (void *) &metadata_id,
-                               sizeof(stream->relayd_stream_id));
+               ret = write(fd, (void *) &hdr, sizeof(hdr));
        } while (ret < 0 && errno == EINTR);
        if (ret < 0) {
                PERROR("write metadata stream id");
                goto end;
        }
-       DBG("Metadata stream id %" PRIu64 " written before data",
-                       stream->relayd_stream_id);
+       DBG("Metadata stream id %" PRIu64 " with padding %lu written before data",
+                       stream->relayd_stream_id, padding);
 
 end:
        return ret;
@@ -1126,7 +1174,8 @@ end:
  */
 ssize_t lttng_consumer_on_read_subbuffer_mmap(
                struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream, unsigned long len)
+               struct lttng_consumer_stream *stream, unsigned long len,
+               unsigned long padding)
 {
        unsigned long mmap_offset;
        ssize_t ret = 0, written = 0;
@@ -1178,17 +1227,17 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                if (stream->metadata_flag) {
                        /* Metadata requires the control socket. */
                        pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       netlen += sizeof(stream->relayd_stream_id);
+                       netlen += sizeof(struct lttcomm_relayd_metadata_payload);
                }
 
-               ret = write_relayd_stream_header(stream, netlen, relayd);
+               ret = write_relayd_stream_header(stream, netlen, padding, relayd);
                if (ret >= 0) {
                        /* Use the returned socket. */
                        outfd = ret;
 
                        /* Write metadata stream id before payload */
                        if (stream->metadata_flag) {
-                               ret = write_relayd_metadata_id(outfd, stream, relayd);
+                               ret = write_relayd_metadata_id(outfd, stream, relayd, padding);
                                if (ret < 0) {
                                        written = ret;
                                        goto end;
@@ -1196,12 +1245,16 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                        }
                }
                /* 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;
        }
 
        while (len > 0) {
                do {
                        ret = write(outfd, stream->mmap_base + mmap_offset, len);
                } while (ret < 0 && errno == EINTR);
+               DBG("Consumer mmap write() ret %zd (len %lu)", ret, len);
                if (ret < 0) {
                        PERROR("Error in file write");
                        if (written == 0) {
@@ -1216,7 +1269,6 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                        len -= ret;
                        mmap_offset += ret;
                }
-               DBG("Consumer mmap write() ret %zd (len %lu)", ret, len);
 
                /* This call is useless on a socket so better save a syscall. */
                if (!relayd) {
@@ -1246,7 +1298,8 @@ end:
  */
 ssize_t lttng_consumer_on_read_subbuffer_splice(
                struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream, unsigned long len)
+               struct lttng_consumer_stream *stream, unsigned long len,
+               unsigned long padding)
 {
        ssize_t ret = 0, written = 0, ret_splice = 0;
        loff_t offset = 0;
@@ -1292,23 +1345,42 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
        }
 
        /* Write metadata stream id before payload */
-       if (stream->metadata_flag && relayd) {
-               /*
-                * Lock the control socket for the complete duration of the function
-                * since from this point on we will use the socket.
-                */
-               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+       if (relayd) {
+               int total_len = len;
 
-               ret = write_relayd_metadata_id(splice_pipe[1], stream, relayd);
-               if (ret < 0) {
-                       written = ret;
+               if (stream->metadata_flag) {
+                       /*
+                        * Lock the control socket for the complete duration of the function
+                        * since from this point on we will use the socket.
+                        */
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+
+                       ret = write_relayd_metadata_id(splice_pipe[1], stream, relayd,
+                                       padding);
+                       if (ret < 0) {
+                               written = ret;
+                               goto end;
+                       }
+
+                       total_len += sizeof(struct lttcomm_relayd_metadata_payload);
+               }
+
+               ret = write_relayd_stream_header(stream, total_len, padding, relayd);
+               if (ret >= 0) {
+                       /* Use the returned socket. */
+                       outfd = ret;
+               } else {
+                       ERR("Remote relayd disconnected. Stopping");
                        goto end;
                }
+       } else {
+               /* No streaming, we have to set the len with the full padding */
+               len += padding;
        }
 
        while (len > 0) {
-               DBG("splice chan to pipe offset %lu of len %lu (fd : %d)",
-                               (unsigned long)offset, len, fd);
+               DBG("splice chan to pipe offset %lu of len %lu (fd : %d, pipe: %d)",
+                               (unsigned long)offset, len, fd, splice_pipe[1]);
                ret_splice = splice(fd, &offset, splice_pipe[1], NULL, len,
                                SPLICE_F_MOVE | SPLICE_F_MORE);
                DBG("splice chan to pipe, ret %zd", ret_splice);
@@ -1324,30 +1396,24 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
                /* Handle stream on the relayd if the output is on the network */
                if (relayd) {
                        if (stream->metadata_flag) {
+                               size_t metadata_payload_size =
+                                       sizeof(struct lttcomm_relayd_metadata_payload);
+
                                /* Update counter to fit the spliced data */
-                               ret_splice += sizeof(stream->relayd_stream_id);
-                               len += sizeof(stream->relayd_stream_id);
+                               ret_splice += metadata_payload_size;
+                               len += metadata_payload_size;
                                /*
                                 * We do this so the return value can match the len passed as
                                 * argument to this function.
                                 */
-                               written -= sizeof(stream->relayd_stream_id);
-                       }
-
-                       ret = write_relayd_stream_header(stream, ret_splice, relayd);
-                       if (ret >= 0) {
-                               /* Use the returned socket. */
-                               outfd = ret;
-                       } else {
-                               ERR("Remote relayd disconnected. Stopping");
-                               goto end;
+                               written -= metadata_payload_size;
                        }
                }
 
                /* Splice data out */
                ret_splice = splice(splice_pipe[0], NULL, outfd, NULL,
                                ret_splice, SPLICE_F_MOVE | SPLICE_F_MORE);
-               DBG("Kernel consumer splice pipe to file, ret %zd", ret_splice);
+               DBG("Consumer splice pipe to file, ret %zd", ret_splice);
                if (ret_splice < 0) {
                        PERROR("Error in file splice");
                        if (written == 0) {
@@ -1468,9 +1534,9 @@ int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 }
 
 /*
- * Iterate over all stream element of the hashtable and free them. This is race
- * free since the hashtable received MUST be in a race free synchronization
- * state. It's the caller responsability to make sure of that.
+ * Iterate over all streams of the hashtable and free them properly.
+ *
+ * XXX: Should not be only for metadata stream or else use an other name.
  */
 static void destroy_stream_ht(struct lttng_ht *ht)
 {
@@ -1482,12 +1548,14 @@ static void destroy_stream_ht(struct lttng_ht *ht)
                return;
        }
 
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, waitfd_node.node) {
                ret = lttng_ht_del(ht, &iter);
                assert(!ret);
 
-               free(stream);
+               call_rcu(&stream->waitfd_node.head, consumer_free_metadata_stream);
        }
+       rcu_read_unlock();
 
        lttng_ht_destroy(ht);
 }
@@ -1495,9 +1563,11 @@ static void destroy_stream_ht(struct lttng_ht *ht)
 /*
  * Clean up a metadata stream and free its memory.
  */
-static void consumer_del_metadata_stream(struct lttng_consumer_stream *stream)
+void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
 {
        int ret;
+       struct lttng_ht_iter iter;
        struct lttng_consumer_channel *free_chan = NULL;
        struct consumer_relayd_sock_pair *relayd;
 
@@ -1508,6 +1578,19 @@ static void consumer_del_metadata_stream(struct lttng_consumer_stream *stream)
         */
        assert(stream->metadata_flag);
 
+       DBG3("Consumer delete metadata stream %d", stream->wait_fd);
+
+       if (ht == NULL) {
+               /* Means the stream was allocated but not successfully added */
+               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);
        switch (consumer_data.type) {
        case LTTNG_CONSUMER_KERNEL:
@@ -1525,8 +1608,8 @@ static void consumer_del_metadata_stream(struct lttng_consumer_stream *stream)
        default:
                ERR("Unknown consumer_data type");
                assert(0);
+               goto end;
        }
-       pthread_mutex_unlock(&consumer_data.lock);
 
        if (stream->out_fd >= 0) {
                ret = close(stream->out_fd);
@@ -1573,39 +1656,100 @@ static void consumer_del_metadata_stream(struct lttng_consumer_stream *stream)
                /* Both conditions are met, we destroy the relayd. */
                if (uatomic_read(&relayd->refcount) == 0 &&
                                uatomic_read(&relayd->destroy_flag)) {
-                       consumer_destroy_relayd(relayd);
+                       destroy_relayd(relayd);
                }
        }
        rcu_read_unlock();
 
        /* Atomically decrement channel refcount since other threads can use it. */
        uatomic_dec(&stream->chan->refcount);
-       if (!uatomic_read(&stream->chan->refcount)) {
+       if (!uatomic_read(&stream->chan->refcount)
+                       && !uatomic_read(&stream->chan->nb_init_streams)) {
+               /* Go for channel deletion! */
                free_chan = stream->chan;
        }
 
+end:
+       pthread_mutex_unlock(&consumer_data.lock);
+
        if (free_chan) {
                consumer_del_channel(free_chan);
        }
 
-       free(stream);
+free_stream:
+       call_rcu(&stream->waitfd_node.head, consumer_free_metadata_stream);
 }
 
 /*
  * Action done with the metadata stream when adding it to the consumer internal
  * data structures to handle it.
  */
-static void consumer_add_metadata_stream(struct lttng_consumer_stream *stream)
+static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
 {
+       int ret = 0;
        struct consumer_relayd_sock_pair *relayd;
 
-       /* Find relayd and, if one is found, increment refcount. */
+       assert(stream);
+       assert(ht);
+
+       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;
+       }
+
+       /*
+        * From here, refcounts are updated so be _careful_ when returning an error
+        * after this point.
+        */
+
        rcu_read_lock();
+       /* Find relayd and, if one is found, increment refcount. */
        relayd = consumer_find_relayd(stream->net_seq_idx);
        if (relayd != NULL) {
                uatomic_inc(&relayd->refcount);
        }
+
+       /* Update channel refcount once added without error(s). */
+       uatomic_inc(&stream->chan->refcount);
+
+       /*
+        * When nb_init_streams reaches 0, we don't need to trigger any action in
+        * terms of destroying the associated channel, because the action that
+        * causes the count to become 0 also causes a stream to be added. The
+        * channel deletion will thus be triggered by the following removal of this
+        * stream.
+        */
+       if (uatomic_read(&stream->chan->nb_init_streams) > 0) {
+               uatomic_dec(&stream->chan->nb_init_streams);
+       }
+
+       lttng_ht_add_unique_ulong(ht, &stream->waitfd_node);
        rcu_read_unlock();
+
+error:
+       pthread_mutex_unlock(&consumer_data.lock);
+       return ret;
 }
 
 /*
@@ -1616,7 +1760,7 @@ void *lttng_consumer_thread_poll_metadata(void *data)
 {
        int ret, i, pollfd;
        uint32_t revents, nb_fd;
-       struct lttng_consumer_stream *stream;
+       struct lttng_consumer_stream *stream = NULL;
        struct lttng_ht_iter iter;
        struct lttng_ht_node_ulong *node;
        struct lttng_ht *metadata_ht = NULL;
@@ -1664,18 +1808,24 @@ restart:
                DBG("Metadata event catched in thread");
                if (ret < 0) {
                        if (errno == EINTR) {
+                               ERR("Poll EINTR catched");
                                goto restart;
                        }
                        goto error;
                }
 
+               /* From here, the event is a metadata wait fd */
                for (i = 0; i < nb_fd; i++) {
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
-                       /* Check the metadata pipe for incoming metadata. */
+                       /* Just don't waste time if no returned events for the fd */
+                       if (!revents) {
+                               continue;
+                       }
+
                        if (pollfd == ctx->consumer_metadata_pipe[0]) {
-                               if (revents & (LPOLLERR | LPOLLHUP | LPOLLNVAL)) {
+                               if (revents & (LPOLLERR | LPOLLHUP )) {
                                        DBG("Metadata thread pipe hung up");
                                        /*
                                         * Remove the pipe from the poll set and continue the loop
@@ -1685,20 +1835,13 @@ restart:
                                        close(ctx->consumer_metadata_pipe[0]);
                                        continue;
                                } else if (revents & LPOLLIN) {
-                                       stream = zmalloc(sizeof(struct lttng_consumer_stream));
-                                       if (stream == NULL) {
-                                               PERROR("zmalloc metadata consumer stream");
-                                               goto error;
-                                       }
-
                                        do {
-                                               /* Get the stream and add it to the local hash table */
-                                               ret = read(pollfd, stream,
-                                                               sizeof(struct lttng_consumer_stream));
+                                               /* Get the stream pointer received */
+                                               ret = read(pollfd, &stream, sizeof(stream));
                                        } while (ret < 0 && errno == EINTR);
-                                       if (ret < 0 || ret < sizeof(struct lttng_consumer_stream)) {
+                                       if (ret < 0 ||
+                                                       ret < sizeof(struct lttng_consumer_stream *)) {
                                                PERROR("read metadata stream");
-                                               free(stream);
                                                /*
                                                 * Let's continue here and hope we can still work
                                                 * without stopping the consumer. XXX: Should we?
@@ -1709,73 +1852,76 @@ restart:
                                        DBG("Adding metadata stream %d to poll set",
                                                        stream->wait_fd);
 
-                                       /* The node should be init at this point */
-                                       lttng_ht_add_unique_ulong(metadata_ht,
-                                                       &stream->waitfd_node);
+                                       ret = consumer_add_metadata_stream(stream, metadata_ht);
+                                       if (ret) {
+                                               ERR("Unable to add metadata stream");
+                                               /* Stream was not setup properly. Continuing. */
+                                               consumer_del_metadata_stream(stream, NULL);
+                                               continue;
+                                       }
 
                                        /* Add metadata stream to the global poll events list */
                                        lttng_poll_add(&events, stream->wait_fd,
                                                        LPOLLIN | LPOLLPRI);
-
-                                       consumer_add_metadata_stream(stream);
                                }
 
-                               /* Metadata pipe handled. Continue handling the others */
+                               /* Handle other stream */
                                continue;
                        }
 
-                       /* From here, the event is a metadata wait fd */
-
+                       rcu_read_lock();
                        lttng_ht_lookup(metadata_ht, (void *)((unsigned long) pollfd),
                                        &iter);
                        node = lttng_ht_iter_get_node_ulong(&iter);
-                       if (node == NULL) {
-                               /* FD not found, continue loop */
-                               continue;
-                       }
+                       assert(node);
 
                        stream = caa_container_of(node, struct lttng_consumer_stream,
                                        waitfd_node);
 
-                       /* Get the data out of the metadata file descriptor */
-                       if (revents & (LPOLLIN | LPOLLPRI)) {
+                       /* Check for error event */
+                       if (revents & (LPOLLERR | LPOLLHUP)) {
+                               DBG("Metadata fd %d is hup|err.", pollfd);
+                               if (!stream->hangup_flush_done
+                                               && (consumer_data.type == LTTNG_CONSUMER32_UST
+                                                       || consumer_data.type == LTTNG_CONSUMER64_UST)) {
+                                       DBG("Attempting to flush and consume the UST buffers");
+                                       lttng_ustconsumer_on_stream_hangup(stream);
+
+                                       /* We just flushed the stream now read it. */
+                                       do {
+                                               len = ctx->on_buffer_ready(stream, ctx);
+                                               /*
+                                                * We don't check the return value here since if we get
+                                                * a negative len, it means an error occured thus we
+                                                * simply remove it from the poll set and free the
+                                                * stream.
+                                                */
+                                       } while (len > 0);
+                               }
+
+                               lttng_poll_del(&events, stream->wait_fd);
+                               /*
+                                * This call update the channel states, closes file descriptors
+                                * and securely free the stream.
+                                */
+                               consumer_del_metadata_stream(stream, metadata_ht);
+                       } else if (revents & (LPOLLIN | LPOLLPRI)) {
+                               /* Get the data out of the metadata file descriptor */
                                DBG("Metadata available on fd %d", pollfd);
                                assert(stream->wait_fd == pollfd);
 
                                len = ctx->on_buffer_ready(stream, ctx);
                                /* It's ok to have an unavailable sub-buffer */
                                if (len < 0 && len != -EAGAIN) {
+                                       rcu_read_unlock();
                                        goto end;
                                } else if (len > 0) {
                                        stream->data_read = 1;
                                }
                        }
 
-                       /*
-                        * Remove the stream from the hash table since there is no data
-                        * left on the fd because we previously did a read on the buffer.
-                        */
-                       if (revents & (LPOLLERR | LPOLLHUP | LPOLLNVAL)) {
-                               DBG("Metadata fd %d is hup|err|nval.", pollfd);
-                               if (!stream->hangup_flush_done
-                                               && (consumer_data.type == LTTNG_CONSUMER32_UST
-                                                       || consumer_data.type == LTTNG_CONSUMER64_UST)) {
-                                       DBG("Attempting to flush and consume the UST buffers");
-                                       lttng_ustconsumer_on_stream_hangup(stream);
-
-                                       /* We just flushed the stream now read it. */
-                                       len = ctx->on_buffer_ready(stream, ctx);
-                                       /* It's ok to have an unavailable sub-buffer */
-                                       if (len < 0 && len != -EAGAIN) {
-                                               goto end;
-                                       }
-                               }
-
-                               /* Removing it from hash table, poll set and free memory */
-                               lttng_ht_del(metadata_ht, &iter);
-                               lttng_poll_del(&events, stream->wait_fd);
-                               consumer_del_metadata_stream(stream);
-                       }
+                       /* Release RCU lock for the stream looked up */
+                       rcu_read_unlock();
                }
        }
 
@@ -1843,7 +1989,7 @@ void *lttng_consumer_thread_poll_fds(void *data)
                        /* allocate for all fds + 1 for the consumer_poll_pipe */
                        pollfd = zmalloc((consumer_data.stream_count + 1) * sizeof(struct pollfd));
                        if (pollfd == NULL) {
-                               perror("pollfd malloc");
+                               PERROR("pollfd malloc");
                                pthread_mutex_unlock(&consumer_data.lock);
                                goto end;
                        }
@@ -1852,7 +1998,7 @@ void *lttng_consumer_thread_poll_fds(void *data)
                        local_stream = zmalloc((consumer_data.stream_count + 1) *
                                        sizeof(struct lttng_consumer_stream));
                        if (local_stream == NULL) {
-                               perror("local_stream malloc");
+                               PERROR("local_stream malloc");
                                pthread_mutex_unlock(&consumer_data.lock);
                                goto end;
                        }
@@ -1884,7 +2030,7 @@ void *lttng_consumer_thread_poll_fds(void *data)
                        if (errno == EINTR) {
                                goto restart;
                        }
-                       perror("Poll error");
+                       PERROR("Poll error");
                        lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
                        goto end;
                } else if (num_rdy == 0) {
@@ -1967,19 +2113,22 @@ void *lttng_consumer_thread_poll_fds(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_del_stream(local_stream[i],
+                                                       consumer_data.stream_ht);
                                        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_del_stream(local_stream[i],
+                                                       consumer_data.stream_ht);
                                        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_del_stream(local_stream[i],
+                                                       consumer_data.stream_ht);
                                        num_hup++;
                                }
                        }
@@ -2056,7 +2205,7 @@ void *lttng_consumer_thread_receive_fds(void *data)
 
        ret = fcntl(client_socket, F_SETFL, O_NONBLOCK);
        if (ret < 0) {
-               perror("fcntl O_NONBLOCK");
+               PERROR("fcntl O_NONBLOCK");
                goto end;
        }
 
@@ -2079,7 +2228,7 @@ void *lttng_consumer_thread_receive_fds(void *data)
        }
        ret = fcntl(sock, F_SETFL, O_NONBLOCK);
        if (ret < 0) {
-               perror("fcntl O_NONBLOCK");
+               PERROR("fcntl O_NONBLOCK");
                goto end;
        }
 
@@ -2269,7 +2418,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
         * Add relayd socket pair to consumer data hashtable. If object already
         * exists or on error, the function gracefully returns.
         */
-       consumer_add_relayd(relayd);
+       add_relayd(relayd);
 
        /* All good! */
        ret = 0;
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