Re: [PATCH bpf-next 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type

[Jakub Kicinski]

On Tue, 23 Apr 2019 16:21:59 -0700, Stanislav Fomichev wrote:
> +     rcu_read_lock();
> +     attached = rcu_dereference(net->flow_dissector_prog);
> +     if (attached) {
> +             cnt = 1;
> +             if (prog_ids &&
> +                 copy_to_user(prog_ids, &attached->aux->id, sizeof(u32))) {

Not sure you can do copy_to_user inside an RCU section, doesn't it
sleep?

> +                     rcu_read_unlock();
> +                     return -EFAULT;
> +             }
> +     }
> +     rcu_read_unlock();