block: fix deadlock in blk_abort_queue() for drivers that readd to timeout list
blk_abort_queue() iterates the timeout list and aborts each request on the
list, but if the driver error handling readds a request to the timeout list
during this processing, we could be looping forever. Fix this by splicing
current entries to a local list and run over that list instead.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index a095353..bbbdc4b 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -209,12 +209,19 @@
{
unsigned long flags;
struct request *rq, *tmp;
+ LIST_HEAD(list);
spin_lock_irqsave(q->queue_lock, flags);
elv_abort_queue(q);
- list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
+ /*
+ * Splice entries to local list, to avoid deadlocking if entries
+ * get readded to the timeout list by error handling
+ */
+ list_splice_init(&q->timeout_list, &list);
+
+ list_for_each_entry_safe(rq, tmp, &list, timeout_list)
blk_abort_request(rq);
spin_unlock_irqrestore(q->queue_lock, flags);