The patch titled
Subject: block: fix blk_queue_end_tag()
has been added to the -mm tree. Its filename is
block-fix-blk_queue_end_tag.patch
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From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: block: fix blk_queue_end_tag()
Commit 5e081591 "block: warn if tag is greater than real_max_depth"
cleaned up blk_queue_end_tag() to warn when the tag is truly invalid
(greater than real_max_depth). However, it changed behavior in the tag <
max_depth case to not end the request. Leading to triggering of
BUG_ON(blk_queued_rq(rq)) in the request completion path:
http://marc.info/?l=linux-kernel&m=132204370518629&w=2
In order to allow blk_queue_resize_tags() to shrink the tag space
blk_queue_end_tag() must always complete tags with a value less than
real_max_depth regardless of the current max_depth. The comment about
"handling the shrink case" seems to be what prompted changes in this
space, so remove it and BUG on all invalid tags (made even simpler by
Matthew's suggestion to use an unsigned compare).
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Tao Ma <boyu.mt@xxxxxxxxxx>
Cc: Matthew Wilcox <matthew@xxxxxx>
Reported-by: Meelis Roos <mroos@xxxxx>
Reported-by: Ed Nadolski <edmund.nadolski@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/blk-tag.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff -puN block/blk-tag.c~block-fix-blk_queue_end_tag block/blk-tag.c
--- a/block/blk-tag.c~block-fix-blk_queue_end_tag
+++ a/block/blk-tag.c
@@ -282,18 +282,9 @@ EXPORT_SYMBOL(blk_queue_resize_tags);
void blk_queue_end_tag(struct request_queue *q, struct request *rq)
{
struct blk_queue_tag *bqt = q->queue_tags;
- int tag = rq->tag;
+ unsigned tag = rq->tag; /* negative tags invalid */
- BUG_ON(tag == -1);
-
- if (unlikely(tag >= bqt->max_depth)) {
- /*
- * This can happen after tag depth has been reduced.
- * But tag shouldn't be larger than real_max_depth.
- */
- WARN_ON(tag >= bqt->real_max_depth);
- return;
- }
+ BUG_ON(tag >= bqt->real_max_depth);
list_del_init(&rq->queuelist);
rq->cmd_flags &= ~REQ_QUEUED;
_
Subject: Subject: block: fix blk_queue_end_tag()
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
block-fix-blk_queue_end_tag.patch
linux-next.patch
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