On Thu, 2018-04-12 at 08:37 -0700, Tejun Heo wrote: > On Thu, Apr 12, 2018 at 08:09:17AM -0600, Bart Van Assche wrote: > > I have retested hotunplugging by rerunning the srp-test software. It > > seems like you overlooked that this patch does not remove the > > blkcg_exit_queue() call from blk_cleanup_queue()? If a device is > > hotunplugged it is up to the block driver to call > > blk_cleanup_queue(). And blk_cleanup_queue() will call > > blkcg_exit_queue(). > > Hmm... what'd prevent blg_lookup_and_create() racing against that? Hello Tejun, Did you perhaps mean blkg_lookup_create()? That function has one caller, namely blkcg_bio_issue_check(). The only caller of that function is generic_make_request_checks(). A patch was posted on the linux-block mailing list recently that surrounds that call with blk_queue_enter() / blk_queue_exit(). I think that prevents that blkcg_exit_queue() is called concurrently with blkg_lookup_create(). Bart.
