Re: [PATCH] b43: Eliminate compilation warning in b43_op_set_key

[Michael Buesch <mb@bu3sch.de>]

On Wednesday 14 January 2009 16:47:09 Larry Finger wrote:
> John W. Linville wrote:
> > On Tue, Jan 13, 2009 at 06:20:25PM -0600, Larry Finger wrote:
> >> A recent pull from wireless testing generates the following warnin=
g:
> >> =20
> >>    CC [M]  drivers/net/wireless/b43/main.o
> >>  drivers/net/wireless/b43/main.c: In function =E2=80=98b43_op_set_=
key=E2=80=99:
> >>  drivers/net/wireless/b43/main.c:3636: warning: pointer type misma=
tch
> >>  in conditional expression
> >>
> >> This fix was suggested by Johannes Berg <johannes@sipsolutions.net=
>.
> >>
> >> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
> >> ---
> >>
> >> Index: wireless-testing/drivers/net/wireless/b43/main.c
> >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> >> --- wireless-testing.orig/drivers/net/wireless/b43/main.c
> >> +++ wireless-testing/drivers/net/wireless/b43/main.c
> >> @@ -3630,10 +3630,12 @@ static int b43_op_set_key(struct ieee802
> >> =20
> >>  out_unlock:
> >>  	if (!err) {
> >> +		u8 bcast[ETH_ALEN];
> >> +		memset(bcast, 0xff, ETH_ALEN);
> >=20
> > Isn't there a statically-allocated array w/ the broadcast MAC in it
> > somewhere already?
> >=20
>=20
> Not that I could find.
>=20
> There are several places in mac80211 where the broadcast MAC is
> created on the fly. None of them would benefit from having a static
> array - one would just substitute memcpy for memset and possibly tras=
h
> the cache.
>=20
> There is an array broadcast[MAX_ADDR_LEN] in struct net_device, but i=
t
> would need to be initialized with 0xFF's before usage.
>=20
> I still think that b43 needs to create this array, and that the best
> place to do it is in the error path that is unlikely to be executed.

This is not an error path.
Why don't you simply define
	static const u8 bcast_addr[] =3D { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,=
 };
It has zero runtime overhead and is much easier to understand.
And the linker will merge the arrays, if there are multiple of these ar=
rays
in the compilation unit.

Note that you might need to wrap this into
#if B43_DEBUG
#endif
to avoid a compilation warning on non-debug builds in any case

--=20
Greetings, Michael.
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