From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: "Jens Axboe" <axboe@kernel.dk>,
"Josef Bacik" <josef@toxicpanda.com>,
"Zefan Li" <lizefan.x@bytedance.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Michal Koutný" <mkoutny@suse.com>,
"Dennis Zhou (Facebook)" <dennisszhou@gmail.com>,
"Yi Zhang" <yi.zhang@redhat.com>
Subject: Re: [PATCH-block v2 1/3] bdi, blk-cgroup: Fix potential UAF of blkcg
Date: Mon, 12 Dec 2022 12:13:47 -1000 [thread overview]
Message-ID: <Y5enmzQM7BIiEv9n@slm.duckdns.org> (raw)
In-Reply-To: <20221211222058.2946830-2-longman@redhat.com>
On Sun, Dec 11, 2022 at 05:20:56PM -0500, Waiman Long wrote:
> static void blkcg_destroy_blkgs(struct blkcg *blkcg)
> {
> + /*
> + * blkcg_destroy_blkgs() shouldn't be called with all the blkcg
> + * references gone.
> + */
> + if (WARN_ON_ONCE(!css_tryget(&blkcg->css)))
> + return;
Wouldn't it make more sense to use percpu_ref_is_zero()? It's not like the
obtained extra reference does anything, right?
Thanks.
--
tejun
next prev parent reply other threads:[~2022-12-12 22:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-11 22:20 [PATCH-block v2 0/3] blk-cgroup: Fix potential UAF & miscellaneous cleanup Waiman Long
2022-12-11 22:20 ` [PATCH-block v2 1/3] bdi, blk-cgroup: Fix potential UAF of blkcg Waiman Long
2022-12-12 22:13 ` Tejun Heo [this message]
2022-12-12 22:16 ` Waiman Long
2022-12-11 22:20 ` [PATCH-block v2 2/3] blk-cgroup: Don't flush a blkg if destroyed Waiman Long
2022-12-12 12:59 ` Michal Koutný
2022-12-12 14:58 ` Waiman Long
2022-12-12 22:16 ` Tejun Heo
2022-12-13 0:21 ` Waiman Long
2022-12-11 22:20 ` [PATCH-block v2 3/3] blk-cgroup: Flush stats at blkgs destruction path Waiman Long
2022-12-12 22:24 ` Tejun Heo
2022-12-13 0:19 ` Waiman Long
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