diff options
| author | Jens Axboe <jens.axboe@oracle.com> | 2007-10-25 10:14:47 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2007-10-29 11:33:06 +0100 |
| commit | 6eca9004dfcb274a502438a591df5b197690afb1 (patch) | |
| tree | fd281ef7c016fbae03e2a27e42a53efd37c3ec63 /block/ll_rw_blk.c | |
| parent | 3a424f2d56613acfb9e583ec9c85a2be3e3af028 (diff) | |
| download | lwn-6eca9004dfcb274a502438a591df5b197690afb1.tar.gz lwn-6eca9004dfcb274a502438a591df5b197690afb1.zip | |
[BLOCK] Fix bad sharing of tag busy list on queues with shared tag maps
For the locking to work, only the tag map and tag bit map may be shared
(incidentally, I was just explaining this to Nick yesterday, but I
apparently didn't review the code well enough myself). But we also share
the busy list! The busy_list must be queue private, or we need a
block_queue_tag covering lock as well.
So we have to move the busy_list to the queue. This'll work fine, and
it'll actually also fix a problem with blk_queue_invalidate_tags() which
will invalidate tags across all shared queues. This is a bit confusing,
the low level driver should call it for each queue seperately since
otherwise you cannot kill tags on just a single queue for eg a hard
drive that stops responding. Since the function has no callers
currently, it's not an issue.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/ll_rw_blk.c')
| -rw-r--r-- | block/ll_rw_blk.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index a8a181072bf8..56f2646612e6 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -791,7 +791,6 @@ static int __blk_free_tags(struct blk_queue_tag *bqt) retval = atomic_dec_and_test(&bqt->refcnt); if (retval) { BUG_ON(bqt->busy); - BUG_ON(!list_empty(&bqt->busy_list)); kfree(bqt->tag_index); bqt->tag_index = NULL; @@ -903,7 +902,6 @@ static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q, if (init_tag_map(q, tags, depth)) goto fail; - INIT_LIST_HEAD(&tags->busy_list); tags->busy = 0; atomic_set(&tags->refcnt, 1); return tags; @@ -954,6 +952,7 @@ int blk_queue_init_tags(struct request_queue *q, int depth, */ q->queue_tags = tags; q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); + INIT_LIST_HEAD(&q->tag_busy_list); return 0; fail: kfree(tags); @@ -1122,7 +1121,7 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq) rq->tag = tag; bqt->tag_index[tag] = rq; blkdev_dequeue_request(rq); - list_add(&rq->queuelist, &bqt->busy_list); + list_add(&rq->queuelist, &q->tag_busy_list); bqt->busy++; return 0; } @@ -1143,11 +1142,10 @@ EXPORT_SYMBOL(blk_queue_start_tag); **/ void blk_queue_invalidate_tags(struct request_queue *q) { - struct blk_queue_tag *bqt = q->queue_tags; struct list_head *tmp, *n; struct request *rq; - list_for_each_safe(tmp, n, &bqt->busy_list) { + list_for_each_safe(tmp, n, &q->tag_busy_list) { rq = list_entry_rq(tmp); if (rq->tag == -1) { |