From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Thu, 9 Jul 2020 21:38:17 +0000 (-0400)
Subject: Fix: consumer: Move sanity check within `consumer_subbuffer` functions
X-Git-Tag: v2.13.0-rc1~585
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=514775d9bca89b3bd072c58e779201682304c57d;p=lttng-tools.git

Fix: consumer: Move sanity check within `consumer_subbuffer` functions

The sanity check on the number bytes written by the `consumer_subbuffer`
callback was not correct channel configured in the splice output type in
a live session.

To simplify this, move checks in the callback themselves so they can be
specialized.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I4e47a305860684c461ba7ffffd5e3bb3a21990b0
---

diff --git a/src/common/consumer/consumer-stream.c b/src/common/consumer/consumer-stream.c
index 8c21d6ae1..1e4b9c92a 100644
--- a/src/common/consumer/consumer-stream.c
+++ b/src/common/consumer/consumer-stream.c
@@ -152,9 +152,40 @@ static ssize_t consumer_stream_consume_mmap(
 	const unsigned long padding_size =
 			subbuffer->info.data.padded_subbuf_size -
 			subbuffer->info.data.subbuf_size;
-
-	return lttng_consumer_on_read_subbuffer_mmap(
+	const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_mmap(
 			stream, &subbuffer->buffer.buffer, padding_size);
+
+	if (stream->net_seq_idx == -1ULL) {
+		/*
+		 * When writing on disk, check that only the subbuffer (no
+		 * padding) was written to disk.
+		 */
+		if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+			DBG("Failed to write the entire padded subbuffer on disk (written_bytes: %zd, padded subbuffer size %lu)",
+					written_bytes,
+					subbuffer->info.data.padded_subbuf_size);
+		}
+	} else {
+		/*
+		 * When streaming over the network, check that the entire
+		 * subbuffer including padding was successfully written.
+		 */
+		if (written_bytes != subbuffer->info.data.subbuf_size) {
+			DBG("Failed to write only the subbuffer over the network (written_bytes: %zd, subbuffer size %lu)",
+					written_bytes,
+					subbuffer->info.data.subbuf_size);
+		}
+	}
+
+	/*
+	 * If `lttng_consumer_on_read_subbuffer_mmap()` returned an error, pass
+	 * it along to the caller, else return zero.
+	 */
+	if (written_bytes < 0) {
+		ERR("Error reading mmap subbuffer: %zd", written_bytes);
+	}
+
+	return written_bytes;
 }
 
 static ssize_t consumer_stream_consume_splice(
@@ -162,8 +193,24 @@ static ssize_t consumer_stream_consume_splice(
 		struct lttng_consumer_stream *stream,
 		const struct stream_subbuffer *subbuffer)
 {
-	return lttng_consumer_on_read_subbuffer_splice(ctx, stream,
-			subbuffer->info.data.padded_subbuf_size, 0);
+	const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_splice(
+			ctx, stream, subbuffer->info.data.padded_subbuf_size, 0);
+
+	if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+		DBG("Failed to write the entire padded subbuffer (written_bytes: %zd, padded subbuffer size %lu)",
+				written_bytes,
+				subbuffer->info.data.padded_subbuf_size);
+	}
+
+	/*
+	 * If `lttng_consumer_on_read_subbuffer_splice()` returned an error,
+	 * pass it along to the caller, else return zero.
+	 */
+	if (written_bytes < 0) {
+		ERR("Error reading splice subbuffer: %zd", written_bytes);
+	}
+
+	return written_bytes;
 }
 
 static int consumer_stream_send_index(
diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
index f18cd2bf7..8d9fa0647 100644
--- a/src/common/consumer/consumer.c
+++ b/src/common/consumer/consumer.c
@@ -3383,24 +3383,10 @@ ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 
 	written_bytes = stream->read_subbuffer_ops.consume_subbuffer(
 			ctx, stream, &subbuffer);
-	/*
-	 * Should write subbuf_size amount of data when network streaming or
-	 * the full padded size when we are not streaming.
-	 */
-	if ((written_bytes != subbuffer.info.data.subbuf_size &&
-			    stream->net_seq_idx != (uint64_t) -1ULL) ||
-			(written_bytes != subbuffer.info.data.padded_subbuf_size &&
-					stream->net_seq_idx ==
-							(uint64_t) -1ULL)) {
-		/*
-		 * Display the error but continue processing to try to
-		 * release the subbuffer. This is a DBG statement
-		 * since this can happen without being a critical
-		 * error.
-		 */
-		DBG("Failed to write to tracefile (written_bytes: %zd != padded subbuffer size: %lu, subbuffer size: %lu)",
-				written_bytes, subbuffer.info.data.padded_subbuf_size,
-				subbuffer.info.data.subbuf_size);
+	if (written_bytes <= 0) {
+		ERR("Error consuming subbuffer: (%zd)", written_bytes);
+		ret = (int) written_bytes;
+		goto error_put_subbuf;
 	}
 
 	ret = stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);