From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH net-next 01/11] ipv6: skb_put_zero() used to optimize code Date: Wed, 14 Jun 2017 12:14:16 -0700 Message-ID: <20170614121416.63a78b0d@xeon-e3> References: <1497451026-3923-1-git-send-email-cugyly@163.com> <20170614084434.3342671d@xeon-e3> <1497466892.9377.5.camel@sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: yuan linyu , netdev@vger.kernel.org, "David S . Miller" , yuan linyu To: Johannes Berg Return-path: Received: from mail-pg0-f54.google.com ([74.125.83.54]:35792 "EHLO mail-pg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751621AbdFNTOX (ORCPT ); Wed, 14 Jun 2017 15:14:23 -0400 Received: by mail-pg0-f54.google.com with SMTP id k71so4224779pgd.2 for ; Wed, 14 Jun 2017 12:14:23 -0700 (PDT) In-Reply-To: <1497466892.9377.5.camel@sipsolutions.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 14 Jun 2017 21:01:32 +0200 Johannes Berg wrote: > On Wed, 2017-06-14 at 08:44 -0700, Stephen Hemminger wrote: > > =20 > > > =C2=A0 memcpy(skb_put(skb, sizeof(ra)), ra, sizeof(ra)); > > > =C2=A0 > > > - hdr =3D (struct mld_msg *) skb_put(skb, sizeof(struct > > > mld_msg)); > > > - memset(hdr, 0, sizeof(struct mld_msg)); > > > + hdr =3D (struct mld_msg *) skb_put_zero(skb, sizeof(struct > > > mld_msg)); =20 > >=20 > > Why does skb_put_zero return char * instead of void *? > > If returned void * it would save having to add lots of casts. > >=20 > > One could even go farther by making skb_put_zero a macro and > > use typeof(). =20 >=20 > I just copied it from skb_put() - you could ask the same there? :) My taste is to have less casts. Never understood why so many skb_ functions returned char *, probably a leftover from older Unix style.