linux-kernel - Re: [PATCH] HID: wiimote: check completion in wiimod_battery_get

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Date:   Mon, 20 Mar 2023 20:08:33 +0100
From:   David Rheinsberg <david.rheinsberg@...il.com>
To:     Nikita Zhandarovich <n.zhandarovich@...tech.ru>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        David Herrmann <dh.herrmann@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH] HID: wiimote: check completion in wiimod_battery_get_property

Hi

On Mon, 20 Mar 2023 at 16:34, Nikita Zhandarovich
<n.zhandarovich@...tech.ru> wrote:
>
> wiimote_cmd_wait() in wiimod_battery_get_property() may signal that the
> task of getting specific battery property was interrupted or timed out.
> There is no need to do any further computation in such cases, so just
> return the error.
>
> Found by Linux Verification Center (linuxtesting.org) with static
> analysis tool SVACE.
>
> Fixes: dcf392313817 ("HID: wiimote: convert BATTERY to module")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
> ---
>  drivers/hid/hid-wiimote-modules.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/hid-wiimote-modules.c b/drivers/hid/hid-wiimote-modules.c
> index dbccdfa63916..9755718d9856 100644
> --- a/drivers/hid/hid-wiimote-modules.c
> +++ b/drivers/hid/hid-wiimote-modules.c
> @@ -220,8 +220,10 @@ static int wiimod_battery_get_property(struct power_supply *psy,
>         wiiproto_req_status(wdata);
>         spin_unlock_irqrestore(&wdata->state.lock, flags);
>
> -       wiimote_cmd_wait(wdata);
> +       ret = wiimote_cmd_wait(wdata);
>         wiimote_cmd_release(wdata);
> +       if (ret)
> +               return ret;

The current code returns cached battery-information in case a
synchronous update did not succeed. Battery information is likely
updated regularly, anyway, so the synchronous update is usually not
required.

I don't think bailing out and returning the error to the caller is
required or gains us anything but more complexity. Or am I missing
something here?

Thanks
David