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authorJens Axboe <jens.axboe@oracle.com>2007-10-30 11:18:15 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2007-11-16 08:12:44 -0800
commit0520fb16465a12dda986d51fc7be3eca6e82603b (patch)
tree8ae08c4ff48af8606ff423d39088f94f179cfc65
parentbba9d994eb41060c8a6e09207f659cf4e26e9384 (diff)
BLOCK: Fix bad sharing of tag busy list on queues with shared tag maps
patch 6eca9004dfcb274a502438a591df5b197690afb1 in mainline. 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. This is fixed with commit 6eca9004dfcb274a502438a591df5b197690afb1 in Linus' tree. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--block/ll_rw_blk.c8
-rw-r--r--include/linux/blkdev.h2
2 files changed, 4 insertions, 6 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index ed39313c4085..026cf2438d59 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -819,7 +819,6 @@ 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;
@@ -931,7 +930,6 @@ 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;
@@ -982,6 +980,7 @@ 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);
@@ -1152,7 +1151,7 @@ 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;
}
@@ -1173,11 +1172,10 @@ 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 b126c6f68e27..d26bbb02a47d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -356,7 +356,6 @@ 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 */
@@ -451,6 +450,7 @@ 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;