Fix: deadlock between UST registry lock and consumer lock

[lttng-tools.git] / src / bin / lttng-sessiond / consumer.c

diff --git a/src/bin/lttng-sessiond/consumer.c b/src/bin/lttng-sessiond/consumer.c
index 42738bcac0589b688fab480cd2599dc2b681353a..b7394d97d2def451211fcf1d993d77350340ca8c 100644 (file)
--- a/src/bin/lttng-sessiond/consumer.c
+++ b/src/bin/lttng-sessiond/consumer.c
@@ -1158,7 +1158,8 @@ end:
 }
 
 /*
- * Send a close metdata command to consumer using the given channel key.
+ * Send a close metadata command to consumer using the given channel key.
+ * Called with registry lock held.
  *
  * Return 0 on success else a negative value.
  */
@@ -1224,7 +1225,8 @@ end:
 }
 
 /*
- * Send metadata string to consumer. Socket lock MUST be acquired.
+ * Send metadata string to consumer.
+ * RCU read-side lock must be held to guarantee existence of socket.
  *
  * Return 0 on success else a negative value.
  */
@@ -1239,6 +1241,8 @@ int consumer_push_metadata(struct consumer_socket *socket,
 
        DBG2("Consumer push metadata to consumer socket %d", *socket->fd_ptr);
 
+       pthread_mutex_lock(socket->lock);
+
        memset(&msg, 0, sizeof(msg));
        msg.cmd_type = LTTNG_CONSUMER_PUSH_METADATA;
        msg.u.push_metadata.key = metadata_key;
@@ -1266,6 +1270,7 @@ int consumer_push_metadata(struct consumer_socket *socket,
        }
 
 end:
+       pthread_mutex_unlock(socket->lock);
        health_code_update();
        return ret;
 }
@@ -1277,7 +1282,7 @@ end:
  */
 int consumer_snapshot_channel(struct consumer_socket *socket, uint64_t key,
                struct snapshot_output *output, int metadata, uid_t uid, gid_t gid,
-               const char *session_path, int wait, int max_stream_size)
+               const char *session_path, int wait, uint64_t nb_packets_per_stream)
 {
        int ret;
        struct lttcomm_consumer_msg msg;
@@ -1291,7 +1296,7 @@ int consumer_snapshot_channel(struct consumer_socket *socket, uint64_t key,
        memset(&msg, 0, sizeof(msg));
        msg.cmd_type = LTTNG_CONSUMER_SNAPSHOT_CHANNEL;
        msg.u.snapshot_channel.key = key;
-       msg.u.snapshot_channel.max_stream_size = max_stream_size;
+       msg.u.snapshot_channel.nb_packets_per_stream = nb_packets_per_stream;
        msg.u.snapshot_channel.metadata = metadata;
 
        if (output->consumer->type == CONSUMER_DST_NET) {