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

Song Liu
2022-03-11T00:46:34Z

On Fri, Mar 4, 2022 at 9:33 AM Benjamin Tissoires
<benjamin.tissoires@redhat.com> 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@redhat.com>
>
> ---
[...]

> + 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;
> +} …