linux-kernel - Re: [PATCH 1/1] staging: ks7010: Fix cast to restricted __le16 in ks_wlan

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Message-ID: <CAExDi1SdL9vvttAnEiroEbgrz0VMxA=dNRU97QqM9E0_sfhW-g@mail.gmail.com>
Date:   Sun, 2 Jul 2017 23:23:53 +0200
From:   Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To:     Janusz Lisiecki <janusz.lisiecki@...il.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Driver Project Developer List 
        <driverdev-devel@...uxdriverproject.org>,
        devel@...verdev.osuosl.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] staging: ks7010: Fix cast to restricted __le16 in ks_wlan_net.c

On Sun, Jul 2, 2017 at 10:49 PM, Janusz Lisiecki
<janusz.lisiecki@...il.com> wrote:
> W dniu 2017-07-02 o 21:38, Luc Van Oostenryck pisze:
>
>> On Sun, Jul 2, 2017 at 4:27 PM, Janusz Lisiecki
>> <janusz.lisiecki@...il.com> wrote:
>>>
>>> This patch fixes the following Sparse warnings in ks_wlan_net.c:
>>> drivers/staging/ks7010/ks_wlan_net.c:1359:24: warning: cast to restricted
>>> __le16
>>> Both sides of assignment are u16 so (as 'ap' is local_ap_t type and
>>> 'capability' member,
>>> have the same as local 'capabilities' type of u16) 'le16_to_cpu' is not
>>> needed
>>
>> It could be that it's ap->capability's type that is wrong (not
>> annotated with __le16).
>> Isn't it?
>>
>> Is ap->capability supposed to hold a little-endian value or a native
>> order value?
>>
>> -- Luc
>
> As I see in ks_hostif.c all assignments to link_ap_info_t->capability threat
> this value as native order (i.e get_ap_information, get_current_ap). As this
> is not a structure which comes from HW we can do the way you suggested.
> Still, as all other places in code threats this as native order value I
> decided to change only one place than many other around to fix Sparse
> warning.

Fine, but then please put this explanation in the commit message.
In others words, be very clear that the change is because ap->capability is in
native order and thus the conversion le16_to_cpu() is wrong and must be removed.

-- Luc