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

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Date:   Mon, 20 Mar 2023 23:13:02 -0700
From:   Nikita Zhandarovich <n.zhandarovich@...tech.ru>
To:     David Rheinsberg <david.rheinsberg@...il.com>
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



On 3/20/23 12:08, David Rheinsberg wrote:
> 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

Hi. I think you are right, my change is not that essential to begin with
and there is no urgency to patch this.

Thanks for your patience,
Nikita