Fix: acquire stream lock during kernel metadata snapshot

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 66ae16bc8f09c224ffd3e1130bf9c1fa0ca0fa13..3455f827b6b715c5415bcb3ee11c0d6147a46972 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -336,7 +336,7 @@ end:
  *
  * Returns 0 on success, < 0 on error
  */
-int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
+static int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
                uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 {
        int ret, use_relayd = 0;
@@ -355,11 +355,12 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        if (!metadata_channel) {
                ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
                ret = -1;
-               goto error;
+               goto error_no_channel;
        }
 
        metadata_stream = metadata_channel->metadata_stream;
        assert(metadata_stream);
+       pthread_mutex_lock(&metadata_stream->lock);
 
        /* Flag once that we have a valid relayd for the stream. */
        if (relayd_id != (uint64_t) -1ULL) {
@@ -369,7 +370,7 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        if (use_relayd) {
                ret = consumer_send_relayd_stream(metadata_stream, path);
                if (ret < 0) {
-                       goto error;
+                       goto error_snapshot;
                }
        } else {
                ret = utils_create_stream_file(path, metadata_stream->name,
@@ -377,7 +378,7 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
                                metadata_stream->tracefile_count_current,
                                metadata_stream->uid, metadata_stream->gid, NULL);
                if (ret < 0) {
-                       goto error;
+                       goto error_snapshot;
                }
                metadata_stream->out_fd = ret;
        }
@@ -390,7 +391,8 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
                        if (ret_read != -EAGAIN) {
                                ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
                                                ret_read);
-                               goto error;
+                               ret = ret_read;
+                               goto error_snapshot;
                        }
                        /* ret_read is negative at this point so we will exit the loop. */
                        continue;
@@ -415,11 +417,12 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        }
 
        ret = 0;
-
+error_snapshot:
+       pthread_mutex_unlock(&metadata_stream->lock);
        cds_list_del(&metadata_stream->send_node);
        consumer_stream_destroy(metadata_stream, NULL);
        metadata_channel->metadata_stream = NULL;
-error:
+error_no_channel:
        rcu_read_unlock();
        return ret;
 }
@@ -1151,7 +1154,6 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                msg.u.rotate_channel.key, ctx);
                if (ret < 0) {
                        ERR("Rotate ready streams failed");
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                }
 
                break;
@@ -1183,19 +1185,20 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        }
        case LTTNG_CONSUMER_ROTATE_PENDING_RELAY:
        {
+               int pending;
                uint32_t pending_reply;
 
                DBG("Consumer rotate pending on relay for session %" PRIu64,
                                msg.u.rotate_pending_relay.session_id);
-               ret = lttng_consumer_rotate_pending_relay(
+               pending = lttng_consumer_rotate_pending_relay(
                                msg.u.rotate_pending_relay.session_id,
                                msg.u.rotate_pending_relay.relayd_id,
                                msg.u.rotate_pending_relay.chunk_id);
-               if (ret < 0) {
+               if (pending < 0) {
                        ERR("Rotate pending relay failed");
                        ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                } else {
-                       pending_reply = !!ret;
+                       pending_reply = !!pending;
                }
 
                health_code_update();
@@ -1206,6 +1209,15 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        goto end_nosignal;
                }
 
+               if (pending < 0) {
+                       /*
+                        * An error occured while running the command;
+                        * don't send the 'pending' flag as the sessiond
+                        * will not read it.
+                        */
+                       break;
+               }
+
                /* Send back returned value to session daemon */
                ret = lttcomm_send_unix_sock(sock, &pending_reply,
                                sizeof(pending_reply));