Re: [PATCH] mac80211: Make addr const in SET_IEEE80211_PERM_ADDR()

[Souptick Joarder]

On Wed, Dec 30, 2015 at 10:35 PM, Bjorn Andersson <bjorn@xxxxxxx> wrote:
> On Wed, Dec 30, 2015 at 8:47 AM, Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
>>
>> HI Bjorn,
>>
>> On Thu, Dec 24, 2015 at 2:03 PM, Bjorn Andersson <bjorn@xxxxxxx> wrote:
>> > Make the addr parameter const in SET_IEEE80211_PERM_ADDR() to save
>> > clients from having to cast away a const qualifier.
>> >
>> > Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
>> > ---
>> >  include/net/mac80211.h | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/include/net/mac80211.h b/include/net/mac80211.h
>> > index 7c30faff245f..a6f3c9c4b7c2 100644
>> > --- a/include/net/mac80211.h
>> > +++ b/include/net/mac80211.h
>> > @@ -2167,7 +2167,7 @@ static inline void SET_IEEE80211_DEV(struct ieee80211_hw *hw, struct device *dev
>> >   * @hw: the &struct ieee80211_hw to set the MAC address for
>> >   * @addr: the address to set
>> >   */
>> > -static inline void SET_IEEE80211_PERM_ADDR(struct ieee80211_hw *hw, u8 *addr)
>> > +static inline void SET_IEEE80211_PERM_ADDR(struct ieee80211_hw *hw, const u8 *addr)
>>
>> I guess without const or with const doesn't make much difference here.
>> Correct me if I am wrong.
>
> For most cases it doesn't make any difference, but in my driver I
> acquire the mac address as a const u8 *. Therefor I need to cast away
> the const part when calling this API.
>
> There's an existing example of this in
> drivers/net/wireless/st/cw1200/main.c line 601.

Is the path correct ? I think path is
drivers/net/wireless/cw1200/main.c line 334

> I think it's safe to assume that this API won't ever modify the passed
> addr buffer, so there would be no future issues of marking the
> parameter const either.

I agree with you.

>
>>
>> >  {
>> >         memcpy(hw->wiphy->perm_addr, addr, ETH_ALEN);
>> >  }
>>
>
> Regards,
> Bjorn

-Souptick
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