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References: <20220304172852.274126-1-benjamin.tissoires@redhat.com> <20220304172852.274126-4-benjamin.tissoires@redhat.com>
In-Reply-To: <20220304172852.274126-4-benjamin.tissoires@redhat.com>
From:   Song Liu <song@kernel.org>
Date:   Fri, 4 Mar 2022 16:23:24 -0800
Message-ID: <CAPhsuW5UmK0TQwjR3_oXLeTix3HimnQdjRLattmM+3i8Y996yA@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2 03/28] HID: hook up with bpf
To:     Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        Jiri Kosina <jikos@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Shuah Khan <shuah@kernel.org>,
        Dave Marchevsky <davemarchevsky@fb.com>,
        Joe Stringer <joe@cilium.io>,
        Tero Kristo <tero.kristo@linux.intel.com>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        linux-kselftest@vger.kernel.org
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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

[...]