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

Song Liu
2022-03-05T00:23:42Z

On Fri, Mar 4, 2022 at 9:31 AM Benjamin Tissoires
<benjamin.tissoires@redhat.com> 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@redhat.com>
>
[...]

> +
> +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 …