blk-ioc: protect ioc_destroy_icq() by 'queue_lock'
Currently, icq is tracked by both request_queue(icq->q_node) and
task(icq->ioc_node), and ioc_clear_queue() from elevator exit is not
safe because it can access the list without protection:
ioc_clear_queue ioc_release_fn
lock queue_lock
list_splice
/* move queue list to a local list */
unlock queue_lock
/*
* lock is released, the local list
* can be accessed through task exit.
*/
lock ioc->lock
while (!hlist_empty)
icq = hlist_entry
lock queue_lock
ioc_destroy_icq
delete icq->ioc_node
while (!list_empty)
icq = list_entry() list_del icq->q_node
/*
* This is not protected by any lock,
* list_entry concurrent with list_del
* is not safe.
*/
unlock queue_lock
unlock ioc->lock
Fix this problem by protecting list 'icq->q_node' by queue_lock from
ioc_clear_queue().
Reported-and-tested-by: Pradeep Pragallapati <quic_pragalla@quicinc.com>
Link: https://lore.kernel.org/lkml/20230517084434.18932-1-quic_pragalla@quicinc.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531073435.2923422-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>