Fix: correctly close metadata on sessiond thread shutdown

Introduce a _close_metadata() function that does not take any locks so
it can be used by multiple call sites with different locking scheme.

Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index d154e4805d657ea9e2f369925b861b9e6a972ac5..6a692b9ba5a8bffd7826bd164dfc3f1de9f8c9df 100644 (file)
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -605,6 +605,45 @@ error:
        rcu_read_unlock();
        return ret;
 }
+/*
+ * Close metadata stream wakeup_fd using the given key to retrieve the channel.
+ * RCU read side lock MUST be acquired before calling this function.
+ *
+ * NOTE: This function does NOT take any channel nor stream lock.
+ *
+ * Return 0 on success else LTTng error code.
+ */
+static int _close_metadata(struct lttng_consumer_channel *channel)
+{
+       int ret = LTTNG_OK;
+
+       assert(channel);
+       assert(channel->type == CONSUMER_CHANNEL_TYPE_METADATA);
+
+       if (channel->switch_timer_enabled == 1) {
+               DBG("Deleting timer on metadata channel");
+               consumer_timer_switch_stop(channel);
+       }
+
+       if (channel->metadata_stream) {
+               ret = ustctl_stream_close_wakeup_fd(channel->metadata_stream->ustream);
+               if (ret < 0) {
+                       ERR("UST consumer unable to close fd of metadata (ret: %d)", ret);
+                       ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+               }
+
+               if (channel->monitor) {
+                       /* Close the read-side in consumer_del_metadata_stream */
+                       ret = close(channel->metadata_stream->ust_metadata_poll_pipe[1]);
+                       if (ret < 0) {
+                               PERROR("Close UST metadata write-side poll pipe");
+                               ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+                       }
+               }
+       }
+
+       return ret;
+}
 
 /*
  * Close metadata stream wakeup_fd using the given key to retrieve the channel.
@@ -639,26 +678,7 @@ static int close_metadata(uint64_t chan_key)
                goto error_unlock;
        }
 
-       if (channel->switch_timer_enabled == 1) {
-               DBG("Deleting timer on metadata channel");
-               consumer_timer_switch_stop(channel);
-       }
-
-       if (channel->metadata_stream) {
-               ret = ustctl_stream_close_wakeup_fd(channel->metadata_stream->ustream);
-               if (ret < 0) {
-                       ERR("UST consumer unable to close fd of metadata (ret: %d)", ret);
-                       ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
-                       goto error_unlock;
-               }
-               if (channel->monitor) {
-                       /* close the read-side in consumer_del_metadata_stream */
-                       ret = close(channel->metadata_stream->ust_metadata_poll_pipe[1]);
-                       if (ret < 0) {
-                               PERROR("Close UST metadata write-side poll pipe");
-                       }
-               }
-       }
+       ret = _close_metadata(channel);
 
 error_unlock:
        pthread_mutex_unlock(&channel->lock);
@@ -1802,7 +1822,6 @@ end:
  */
 void lttng_ustconsumer_close_metadata(struct lttng_ht *metadata_ht)
 {
-       int ret;
        struct lttng_ht_iter iter;
        struct lttng_consumer_stream *stream;
 
@@ -1814,17 +1833,16 @@ void lttng_ustconsumer_close_metadata(struct lttng_ht *metadata_ht)
        rcu_read_lock();
        cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream,
                        node.node) {
-               int fd = stream->wait_fd;
-
+               pthread_mutex_lock(&stream->chan->lock);
                /*
-                * Whatever happens here we have to continue to try to close every
-                * streams. Let's report at least the error on failure.
+                * Whatever returned value, we must continue to try to close everything
+                * so ignore it.
                 */
-               ret = ustctl_stream_close_wakeup_fd(stream->ustream);
-               if (ret) {
-                       ERR("Unable to close metadata stream fd %d ret %d", fd, ret);
-               }
-               DBG("Metadata wait fd %d closed", fd);
+               (void) _close_metadata(stream->chan);
+               DBG("Metadata wait fd %d and poll pipe fd %d closed", stream->wait_fd,
+                               stream->ust_metadata_poll_pipe[1]);
+               pthread_mutex_unlock(&stream->chan->lock);
+
        }
        rcu_read_unlock();
 }