X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Fkernel-consumer%2Fkernel-consumer.c;fp=src%2Fcommon%2Fkernel-consumer%2Fkernel-consumer.c;h=70ca8b21e50714982b9d23dc5b32a92d6f11b2a3;hb=24cb9f69c5b6247c8c955252f7e468d4c473d4f1;hp=819dbf20ae80b435885f6ec6320e8e05777d95a7;hpb=1bfbabab0171e4243edbf1d7e9e9b6c11f549460;p=lttng-tools.git

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 819dbf20a..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);
@@ -1506,6 +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;
 	}
 
@@ -1587,6 +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;
 }