Subject: Re: [PATCH bpf-next v2 11/28] samples/bpf: add a report descriptor fixup

From: Greg KH <[email-masked]>
Date: Fri, 4 Mar 2022 19:36:18 +0100

On Fri, Mar 04, 2022 at 06:28:35PM +0100, Benjamin Tissoires wrote:
> the program inverts the definition of X and Y at a given place in the
> report descriptor of my mouse.
> 
> Signed-off-by: Benjamin Tissoires <[email-masked]>
> 
> ---
> 
> changes in v2:
> - split the series by bpf/libbpf/hid/selftests and samples
> ---
>  samples/bpf/hid_mouse_kern.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/samples/bpf/hid_mouse_kern.c b/samples/bpf/hid_mouse_kern.c
> index c24a12e06b40..958820caaf5d 100644
> --- a/samples/bpf/hid_mouse_kern.c
> +++ b/samples/bpf/hid_mouse_kern.c
> @@ -62,5 +62,30 @@ int hid_x_event(struct hid_bpf_ctx *ctx)
>  	return 0;
>  }
>  
> +SEC("hid/rdesc_fixup")
> +int hid_rdesc_fixup(struct hid_bpf_ctx *ctx)

No comment here to show the same as you put in the changelog saying what
this function is doing?

Otherwise it's hard for a non-HID developer to know that:

> +
> +	ctx->data[39] = 0x31;
> +	ctx->data[41] = 0x30;

Is flipping things.

thanks,

greg k-h