Re: [PATCH v2 1/2] block: add BPF kfuncs to read blkcg io.stat

Ziyang Men <[email protected]> Tue, 18 Aug 2026 16:01:58 -0700

Newsgroups	org.kernel.vger.linux-block,org.kernel.vger.bpf,org.kernel.vger.cgroups,org.kernel.vger.linux-kernel,org.kernel.vger.linux-kselftest
Message-ID	<[email protected]>

Hi Tejun,

On Tue, Aug 18, 2026 at 12:42:54PM -1000, Tejun Heo wrote:
>On Tue, Aug 18, 2026 at 03:31:29PM -0700, Ziyang Men wrote:
>> Ok I will add the casts bpf_get_blkcg() and bpf_put_blkcg(), and remove the
>> check of css->ss in above functoins.
>
>RCU_PROTECTED is probably better than get/put().

Yes we can make the blkcg* RCU_PROTECTED but then the bpf_blkcg_flush_stats()
needs to take the @cgroup* since it is SLEEPABLE. Does this work for you?

Best,
Ziyang

>
>Thanks.
>
>-- 
>tejun