From 6eca9004dfcb274a502438a591df5b197690afb1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 25 Oct 2007 10:14:47 +0200 Subject: [PATCH] [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 --- block/ll_rw_blk.c | 8 +++----- include/linux/blkdev.h | 2 +- 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index a8a1810..56f2646 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) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index bbf906a..8396db2 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -341,7 +341,6 @@ enum blk_queue_state { struct blk_queue_tag { struct request **tag_index; /* map of busy tags */ unsigned long *tag_map; /* bit map of free/busy tags */ - struct list_head busy_list; /* fifo list of busy tags */ int busy; /* current depth */ int max_depth; /* what we will send to device */ int real_max_depth; /* what the array can hold */ @@ -435,6 +434,7 @@ struct request_queue unsigned int dma_alignment; struct blk_queue_tag *queue_tags; + struct list_head tag_busy_list; unsigned int nr_sorted; unsigned int in_flight; -- 2.7.4