Fix: ust-consumer: segfault on snapshot after regenerate metadata

[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.cpp

diff --git a/src/common/kernel-consumer/kernel-consumer.cpp b/src/common/kernel-consumer/kernel-consumer.cpp
index aa443027effe021529816ad6a1ea7ffbd8dc3163..8a6ef2a2760e14b7047785add29632589855cfb3 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.cpp
+++ b/src/common/kernel-consumer/kernel-consumer.cpp
@@ -138,7 +138,7 @@ error:
 /*
  * Take a snapshot of all the stream of a channel
  * RCU read-side lock must be held across this function to ensure existence of
 /*
  * Take a snapshot of all the stream of a channel
  * RCU read-side lock must be held across this function to ensure existence of

- * channel. The channel lock must be held by the caller.
+ * channel.

  *
  * Returns 0 on success, < 0 on error
  */
  *
  * Returns 0 on success, < 0 on error
  */


@@ -153,6 +153,9 @@ static int lttng_kconsumer_snapshot_channel(
 
        DBG("Kernel consumer snapshot channel %" PRIu64, key);
 
 
        DBG("Kernel consumer snapshot channel %" PRIu64, key);
 

+       /* Prevent channel modifications while we perform the snapshot.*/
+       pthread_mutex_lock(&channel->lock);
+

        rcu_read_lock();
 
        /* Splice is not supported yet for channel snapshot. */
        rcu_read_lock();
 
        /* Splice is not supported yet for channel snapshot. */


@@ -346,13 +349,14 @@ end_unlock:
        pthread_mutex_unlock(&stream->lock);
 end:
        rcu_read_unlock();
        pthread_mutex_unlock(&stream->lock);
 end:
        rcu_read_unlock();

+       pthread_mutex_unlock(&channel->lock);

        return ret;
 }
 
 /*
  * Read the whole metadata available for a snapshot.
  * RCU read-side lock must be held across this function to ensure existence of
        return ret;
 }
 
 /*
  * Read the whole metadata available for a snapshot.
  * RCU read-side lock must be held across this function to ensure existence of

- * metadata_channel. The channel lock must be held by the caller.
+ * metadata_channel.

  *
  * Returns 0 on success, < 0 on error
  */
  *
  * Returns 0 on success, < 0 on error
  */


@@ -375,7 +379,7 @@ static int lttng_kconsumer_snapshot_metadata(
        metadata_stream = metadata_channel->metadata_stream;
        LTTNG_ASSERT(metadata_stream);
 
        metadata_stream = metadata_channel->metadata_stream;
        LTTNG_ASSERT(metadata_stream);
 

-       pthread_mutex_lock(&metadata_stream->lock);
+       metadata_stream->read_subbuffer_ops.lock(metadata_stream);

        LTTNG_ASSERT(metadata_channel->trace_chunk);
        LTTNG_ASSERT(metadata_stream->trace_chunk);
 
        LTTNG_ASSERT(metadata_channel->trace_chunk);
        LTTNG_ASSERT(metadata_stream->trace_chunk);
 


@@ -430,7 +434,7 @@ static int lttng_kconsumer_snapshot_metadata(
 
        ret = 0;
 error_snapshot:
 
        ret = 0;
 error_snapshot:

-       pthread_mutex_unlock(&metadata_stream->lock);
+       metadata_stream->read_subbuffer_ops.unlock(metadata_stream);

        cds_list_del(&metadata_stream->send_node);
        consumer_stream_destroy(metadata_stream, NULL);
        metadata_channel->metadata_stream = NULL;
        cds_list_del(&metadata_stream->send_node);
        consumer_stream_destroy(metadata_stream, NULL);
        metadata_channel->metadata_stream = NULL;


@@ -960,7 +964,6 @@ error_streams_sent_nosignal:
                        ERR("Channel %" PRIu64 " not found", key);
                        ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                } else {
                        ERR("Channel %" PRIu64 " not found", key);
                        ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                } else {

-                       pthread_mutex_lock(&channel->lock);

                        if (msg.u.snapshot_channel.metadata == 1) {
                                int ret_snapshot;
 
                        if (msg.u.snapshot_channel.metadata == 1) {
                                int ret_snapshot;
 


@@ -988,7 +991,6 @@ error_streams_sent_nosignal:
                                        ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
                                }
                        }
                                        ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
                                }
                        }

-                       pthread_mutex_unlock(&channel->lock);

                }
                health_code_update();
 
                }
                health_code_update();