On Fri, 2019-04-26 at 17:11 +0200, Christoph Hellwig wrote: > On Thu, Apr 25, 2019 at 09:00:31AM +0800, Ming Lei wrote: > > The issue is driver(NVMe) specific, the race window is just between > > between blk_cleanup_queue() and removing the ns from the controller namspace > > list in nvme_ns_remove() > > And I wouldn't be surprised if others have the same issue. > > > > > blk_mq_init_queue() does hold one refcount, and its counter-part is > > blk_cleanup_queue(). > > > > It is simply ugly to ask blk_mq_init_queue() to grab a refcnt for driver, > > then who is the counter-part for releasing the extra refcount? > > Well, the problem is exactly that blk_cleanup_queue drops the reference. > If move the blk_put_queue() call from the end of it to the callers the > callers can keep the reference as long as they need them, and we wouldn't > need an extra reference.
Hi Christoph, There are more than hundred callers of blk_cleanup_queue() so that change would cause a lot of churn. Since blk_get_queue() and blk_put_queue() are available, how inserting a pair of calls to these functions where necessary? Thanks, Bart.
