Re: [PATCH bpf-next v2 15/28] bpf/hid: add new BPF type to trigger commands from userspace

[Song Liu]

On Fri, Mar 4, 2022 at 9:33 AM Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxxx> wrote:
>
> Given that we can not call bpf_hid_raw_request() from within an IRQ,
> userspace needs to have a way to communicate with the device when
> it needs.
>
> Implement a new type that the caller can run at will without being in
> an IRQ context.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>
> ---
[...]

> +       if (user_size_out && data_out) {
> +               user_size_out = min3(user_size_out, (u32)ctx->size, (u32)ctx->allocated_size);
> +
> +               if (copy_to_user(data_out, ctx->data, user_size_out)) {
> +                       ret = -EFAULT;
> +                       goto unlock;
> +               }
> +
> +               if (copy_to_user(&uattr->test.data_size_out,
> +                                &user_size_out,
> +                                sizeof(user_size_out))) {
> +                       ret = -EFAULT;
> +                       goto unlock;
> +               }
> +       }
> +
> +       if (copy_to_user(&uattr->test.retval, &ctx->u.user.retval, sizeof(ctx->u.user.retval))) {
> +               ret = -EFAULT;
> +               goto unlock;

nit: this goto is not really needed.

> +       }
> +
> +unlock:
> +       kfree(ctx);
> +
> +       mutex_unlock(&bpf_hid_mutex);
> +       return ret;
> +}
[...]