From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <b.a.t.m.a.n-bounces@lists.open-mesh.org>
From: Sven Eckelmann <sven@narfation.org>
Subject: Re: [PATCH v3 3/5] batman-adv: mcast: implement multicast packet
 reception and forwarding
Date: Tue, 27 Dec 2022 13:47:42 +0100
Message-ID: <2126960.yKVeVyVuyW@sven-l14>
In-Reply-To: <Y6rd8cwPi8JqTbkN@sellars>
References: <20221226204237.10403-1-linus.luessing@c0d3.blue>
 <8399468.NyiUUSuA9g@sven-l14> <Y6rd8cwPi8JqTbkN@sellars>
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="nextPart2292924.OBFZWjSADL";
 micalg="pgp-sha512"; protocol="application/pgp-signature"
Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking
 <b.a.t.m.a.n@lists.open-mesh.org>
List-Id: The list for a Better Approach To Mobile Ad-hoc Networking
 <b.a.t.m.a.n.lists.open-mesh.org>
List-Archive: 
 <https://lists.open-mesh.org/mailman3/hyperkitty/list/b.a.t.m.a.n@lists.open-mesh.org/>
List-Help: <mailto:b.a.t.m.a.n-request@lists.open-mesh.org?subject=help>
List-Post: <mailto:b.a.t.m.a.n@lists.open-mesh.org>
List-Subscribe: <mailto:b.a.t.m.a.n-join@lists.open-mesh.org>
List-Unsubscribe: <mailto:b.a.t.m.a.n-leave@lists.open-mesh.org>
To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org>
Cc: Linus =?ISO-8859-1?Q?L=FCssing?= <linus.luessing@c0d3.blue>

 
--nextPart2292924.OBFZWjSADL
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset="iso-8859-1"; protected-headers="v1"
From: Sven Eckelmann <sven@narfation.org>
Cc: Linus =?ISO-8859-1?Q?L=FCssing?= <linus.luessing@c0d3.blue>
Date: Tue, 27 Dec 2022 13:47:42 +0100
Message-ID: <2126960.yKVeVyVuyW@sven-l14>
In-Reply-To: <Y6rd8cwPi8JqTbkN@sellars>
MIME-Version: 1.0

On Tuesday, 27 December 2022 12:58:41 CET Linus L=FCssing wrote:
> On Tue, Dec 27, 2022 at 10:07:36AM +0100, Sven Eckelmann wrote:
> > ecsv/pu: checkpatch ./net/batman-adv/multicast_forw.c
> > -----------------------------------------------------
> >=20
> >     CHECK: Macro argument reuse 'num_dests' - possible side-effects?
> >     #25: FILE: ./net/batman-adv/multicast_forw.c:25:
> >     +#define batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) \
> >     +   for (; num_dests; num_dests--, (dest) +=3D ETH_ALEN)
> >    =20
> >     total: 0 errors, 0 warnings, 1 checks, 274 lines checked
> >=20
>=20
> For this I'm not quite sure how to best silence this. I tried
> the workaround of passing num_dests as a pointer and dereferencing
> it inside the macro:
>=20
> #define batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) \
>         for (; (*(num_dests)); (*(num_dests))--, (dest) +=3D ETH_ALEN)

This doesn't make a lot of sense. The checkpatch output is about using the=
=20
same argument multiple times. It is explicitly talking about following=20
situation.


    #define asd(b) \
        do {
             if (b)
                 printk("Foobar %d\n", b);
        while (1)

    ....
    asd(x++);

Which would then be transformed to following by the preprocessor:

        do {
             if (x++)
                 printk("Foobar %d\n", x++);
        while (1)

So your x after the "call" of asd() would (sometimes) not be x+1 but x+2.

> So just like you'd do if you would want intentional side-effects with
> a normal function. But seems like checkpatch does not recoginze it.
>=20
> Also all the other for_each macros in the kernel code have
> side-effects, as far as I know?
>=20
> Or would you have another idea?

Provide a patch for checkpatch or build_test.git (which would otherwise sen=
d=20
this output every day).

Kind regards,
	Sven
--nextPart2292924.OBFZWjSADL
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part.
Content-Transfer-Encoding: 7Bit

-----BEGIN PGP SIGNATURE-----
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=YHOC
-----END PGP SIGNATURE-----

--nextPart2292924.OBFZWjSADL--