X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Fkernel-consumer%2Fkernel-consumer.c;h=70ca8b21e50714982b9d23dc5b32a92d6f11b2a3;hb=24cb9f69c5b6247c8c955252f7e468d4c473d4f1;hp=7e0b36540f306b99deabeb551f1940a341352722;hpb=8d18bcaede97b6d87e434310da9c13d269983c77;p=lttng-tools.git

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 7e0b36540..70ca8b21e 100644
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -413,16 +413,12 @@ static int lttng_kconsumer_snapshot_metadata(
 
 		ret_read = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
 		if (ret_read < 0) {
-			if (ret_read != -EAGAIN) {
-				ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
-						ret_read);
-				ret = ret_read;
-				goto error_snapshot;
-			}
-			/* ret_read is negative at this point so we will exit the loop. */
-			continue;
+			ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
+					ret_read);
+			ret = ret_read;
+			goto error_snapshot;
 		}
-	} while (ret_read >= 0);
+	} while (ret_read > 0);
 
 	if (use_relayd) {
 		close_relayd_stream(metadata_stream);
@@ -1341,36 +1337,38 @@ end:
  * metadata thread can consumer them.
  *
  * Metadata stream lock MUST be acquired.
- *
- * Return 0 if new metadatda is available, EAGAIN if the metadata stream
- * is empty or a negative value on error.
  */
-int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
+enum sync_metadata_status lttng_kconsumer_sync_metadata(
+		struct lttng_consumer_stream *metadata)
 {
 	int ret;
+	enum sync_metadata_status status;
 
 	assert(metadata);
 
 	ret = kernctl_buffer_flush(metadata->wait_fd);
 	if (ret < 0) {
 		ERR("Failed to flush kernel stream");
+		status = SYNC_METADATA_STATUS_ERROR;
 		goto end;
 	}
 
 	ret = kernctl_snapshot(metadata->wait_fd);
 	if (ret < 0) {
-		if (ret != -EAGAIN) {
+		if (errno == EAGAIN) {
+			/* No new metadata, exit. */
+			DBG("Sync metadata, no new kernel metadata");
+			status = SYNC_METADATA_STATUS_NO_DATA;
+		} else {
 			ERR("Sync metadata, taking kernel snapshot failed.");
-			goto end;
+			status = SYNC_METADATA_STATUS_ERROR;
 		}
-		DBG("Sync metadata, no new kernel metadata");
-		/* No new metadata, exit. */
-		ret = ENODATA;
-		goto end;
+	} else {
+		status = SYNC_METADATA_STATUS_NEW_DATA;
 	}
 
 end:
-	return ret;
+	return status;
 }
 
 static
@@ -1504,6 +1502,17 @@ int get_subbuffer_common(struct lttng_consumer_stream *stream,
 
 	ret = kernctl_get_next_subbuf(stream->wait_fd);
 	if (ret) {
+		/*
+		 * The caller only expects -ENODATA when there is no data to
+		 * read, but the kernel tracer returns -EAGAIN when there is
+		 * currently no data for a non-finalized stream, and -ENODATA
+		 * when there is no data for a finalized stream. Those can be
+		 * combined into a -ENODATA return value.
+		 */
+		if (ret == -EAGAIN) {
+			ret = -ENODATA;
+		}
+
 		goto end;
 	}
 
@@ -1585,6 +1594,16 @@ int get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
 			subbuffer->info.metadata.padded_subbuf_size,
 			coherent ? "true" : "false");
 end:
+	/*
+	 * The caller only expects -ENODATA when there is no data to read, but
+	 * the kernel tracer returns -EAGAIN when there is currently no data
+	 * for a non-finalized stream, and -ENODATA when there is no data for a
+	 * finalized stream. Those can be combined into a -ENODATA return value.
+	 */
+	if (ret == -EAGAIN) {
+		ret = -ENODATA;
+	}
+
 	return ret;
 }
 
@@ -1609,8 +1628,23 @@ int put_next_subbuffer(struct lttng_consumer_stream *stream,
 static
 bool is_get_next_check_metadata_available(int tracer_fd)
 {
-	return kernctl_get_next_subbuf_metadata_check(tracer_fd, NULL) !=
-			-ENOTTY;
+	const int ret = kernctl_get_next_subbuf_metadata_check(tracer_fd, NULL);
+	const bool available = ret != -ENOTTY;
+
+	if (ret == 0) {
+		/* get succeeded, make sure to put the subbuffer. */
+		kernctl_put_subbuf(tracer_fd);
+	}
+
+	return available;
+}
+
+static
+int signal_metadata(struct lttng_consumer_stream *stream,
+		struct lttng_consumer_local_data *ctx)
+{
+	ASSERT_LOCKED(stream->metadata_rdv_lock);
+	return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
 }
 
 static
@@ -1643,6 +1677,8 @@ int lttng_kconsumer_set_stream_ops(
 			metadata_bucket_destroy(stream->metadata_bucket);
 			stream->metadata_bucket = NULL;
 		}
+
+		stream->read_subbuffer_ops.on_sleep = signal_metadata;
 	}
 
 	if (!stream->read_subbuffer_ops.get_next_subbuffer) {