Messages in this thread | | | Date | Mon, 6 Dec 2021 16:43:01 +0100 | From | Michal Koutný <> | Subject | Re: [PATCH v4 2/2] block: cancel all throttled bios in del_gendisk() |
| |
On Sat, Dec 04, 2021 at 04:03:53PM +0800, "yukuai (C)" <yukuai3@huawei.com> wrote: > I was thinking that if there are active blkgs, holding queue_lock will > ensure blkcg won't be freed.
My take is that the function traverses the whole blkcg tree (from global root) and nothing prevents concurrent blkcg_css_free() in a possibly unrelated branch (or queue).
> By the way, does spin_lock can guarantee this since it disables preempt > like what rcu_read_lock() does?
Yes (but don't quoRTe me on that :-).
(It even isn't issue with a non-preemptible kernel neither but the code IMO should be generic to allow for different configs -- or as I mentioned initially, make a comment why the tree traversal is not affected by concurrent frees.)
Thanks, Michal [unhandled content-type:application/pgp-signature] | |