Re: [PATCH bpf-next v2 03/28] HID: hook up with bpf

[Song Liu]

On Fri, Mar 4, 2022 at 9:31 AM Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxxx> wrote:
>
> Now that BPF can be compatible with HID, add the capability into HID.
> drivers/hid/hid-bpf.c takes care of the glue between bpf and HID, and
> hid-core can then inject any incoming event from the device into a BPF
> program to filter/analyze it.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>
[...]

> +
> +static int hid_bpf_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type)
> +{
> +       int err = 0;
> +
> +       switch (type) {
> +       case BPF_HID_ATTACH_DEVICE_EVENT:
> +               if (!hdev->bpf.ctx) {
> +                       hdev->bpf.ctx = bpf_hid_allocate_ctx(hdev, HID_BPF_MAX_BUFFER_SIZE);
> +                       if (IS_ERR(hdev->bpf.ctx)) {
> +                               err = PTR_ERR(hdev->bpf.ctx);
> +                               hdev->bpf.ctx = NULL;
> +                       }
> +               }
> +               break;
> +       default:
> +               /* do nothing */

Do we need to show warning and/or return EINVAL here?

> +       }
> +
> +       return err;
> +}
> +
> +static void hid_bpf_array_detached(struct hid_device *hdev, enum bpf_hid_attach_type type)
> +{
> +       switch (type) {
> +       case BPF_HID_ATTACH_DEVICE_EVENT:
> +               kfree(hdev->bpf.ctx);
> +               hdev->bpf.ctx = NULL;
> +               break;
> +       default:
> +               /* do nothing */

ditto

[...]