Re: [RFC patch 1/5] trace event block fix unassigned field

[Jeff Moyer <jmoyer@redhat.com>]

Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:

> The "error" field in block_bio_complete is not assigned, leaving the memory area
> uninitialized (keeping garbage data). Initialize it to 0.
>
> We should eventually remove this field when we find out if blktrace can live
> without it.

Well, I'm fairly sure blkparse has the ability to print this field out,
so we should probably just fill it in properly.  Something like the
following untested patch should do.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7cb1352..f4d83f2 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -630,7 +630,7 @@ static void dec_pending(struct dm_io *io, int error)
 			queue_io(md, bio);
 		} else {
 			/* done with normal IO or empty flush */
-			trace_block_bio_complete(md->queue, bio);
+			trace_block_bio_complete(md->queue, bio, io_error);
 			bio_endio(bio, io_error);
 		}
 	}
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index d8ce278..8990a62 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -212,7 +212,7 @@ TRACE_EVENT(block_bio_bounce,
  */
 TRACE_EVENT(block_bio_complete,
 
-	TP_PROTO(struct request_queue *q, struct bio *bio),
+	TP_PROTO(struct request_queue *q, struct bio *bio, int error),
 
 	TP_ARGS(q, bio),
 
@@ -228,6 +228,7 @@ TRACE_EVENT(block_bio_complete,
 		__entry->dev		= bio->bi_bdev->bd_dev;
 		__entry->sector		= bio->bi_sector;
 		__entry->nr_sector	= bio->bi_size >> 9;
+		__entry->error		= error;
 		blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
 	),