X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fust-consumer%2Fust-consumer.c;h=e7d6dd4e780084879759055fe839e018f6d02048;hp=1544ddb914eff5eb9b6bc69727034d880cd18cf6;hb=1d4dfdefb6efe31cd6436931f893caf7b05d0223;hpb=1f2f41593be38847883eaf11ca8f5db08adec5a1

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index 1544ddb91..e7d6dd4e7 100644
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -399,7 +399,7 @@ void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		struct lttng_consumer_local_data *ctx)
 {
-	unsigned long len;
+	unsigned long len, subbuf_size, padding;
 	int err;
 	long ret = 0;
 	struct lttng_ust_shm_handle *handle;
@@ -426,7 +426,7 @@ int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 	/* Get the next subbuffer */
 	err = ustctl_get_next_subbuf(handle, buf);
 	if (err != 0) {
-		ret = -err;	/* ustctl_get_next_subbuf returns negative, caller expect positive. */
+		ret = err;	/* ustctl_get_next_subbuf returns negative, caller expect positive. */
 		/*
 		 * This is a debug message even for single-threaded consumer,
 		 * because poll() have more relaxed criterions than get subbuf,
@@ -438,12 +438,21 @@ int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		goto end;
 	}
 	assert(stream->output == LTTNG_EVENT_MMAP);
-	/* read the used subbuffer size */
+	/* Get the full padded subbuffer size */
 	err = ustctl_get_padded_subbuf_size(handle, buf, &len);
 	assert(err == 0);
+
+	/* Get subbuffer data size (without padding) */
+	err = ustctl_get_subbuf_size(handle, buf, &subbuf_size);
+	assert(err == 0);
+
+	/* Make sure we don't get a subbuffer size bigger than the padded */
+	assert(len >= subbuf_size);
+
+	padding = len - subbuf_size;
 	/* write the subbuffer to the tracefile */
-	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
-	if (ret != len) {
+	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size, padding);
+	if (ret != subbuf_size) {
 		/*
 		 * display the error but continue processing to try
 		 * to release the subbuffer