From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC8D2C4360C for ; Sun, 13 Oct 2019 22:41:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9F5320663 for ; Sun, 13 Oct 2019 22:41:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729618AbfJMWls (ORCPT ); Sun, 13 Oct 2019 18:41:48 -0400 Received: from shells.gnugeneration.com ([66.240.222.126]:45326 "EHLO shells.gnugeneration.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728198AbfJMWls (ORCPT ); Sun, 13 Oct 2019 18:41:48 -0400 Received: by shells.gnugeneration.com (Postfix, from userid 1000) id 75C951A40559; Sun, 13 Oct 2019 15:41:48 -0700 (PDT) Date: Sun, 13 Oct 2019 15:41:48 -0700 From: Vito Caputo To: Eric Dumazet Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: core: datagram: tidy up copy functions a bit Message-ID: <20191013224148.omivenr6fwmq66fe@shells.gnugeneration.com> References: <20191012115509.jrqe43yozs7kknv5@shells.gnugeneration.com> <8fab6f9c-70a6-02fd-5b2d-66a013c10a4f@gmail.com> <20191013200158.mhvwkdnsjk7ecuqu@shells.gnugeneration.com> <6864f888-1b62-36c5-6ac5-d5db01c5fcfb@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6864f888-1b62-36c5-6ac5-d5db01c5fcfb@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Oct 13, 2019 at 01:17:18PM -0700, Eric Dumazet wrote: > > > On 10/13/19 1:01 PM, Vito Caputo wrote: > > On Sun, Oct 13, 2019 at 12:30:41PM -0700, Eric Dumazet wrote: > >> > >> > >> On 10/12/19 4:55 AM, Vito Caputo wrote: > >>> Eliminate some verbosity by using min() macro and consolidating some > >>> things, also fix inconsistent zero tests (! vs. == 0). > >>> > >>> Signed-off-by: Vito Caputo > >>> --- > >>> net/core/datagram.c | 44 ++++++++++++++------------------------------ > >>> 1 file changed, 14 insertions(+), 30 deletions(-) > >>> > >>> diff --git a/net/core/datagram.c b/net/core/datagram.c > >>> index 4cc8dc5db2b7..08d403f93952 100644 > >>> --- a/net/core/datagram.c > >>> +++ b/net/core/datagram.c > >>> @@ -413,13 +413,11 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset, > >>> struct iov_iter *), void *data) > >>> { > >>> int start = skb_headlen(skb); > >>> - int i, copy = start - offset, start_off = offset, n; > >>> + int i, copy, start_off = offset, n; > >>> struct sk_buff *frag_iter; > >>> > >>> /* Copy header. */ > >>> - if (copy > 0) { > >>> - if (copy > len) > >>> - copy = len; > >>> + if ((copy = min(start - offset, len)) > 0) { > >> > >> No, we prefer not having this kind of construct anymore. > >> > >> This refactoring looks unnecessary code churn, making our future backports not > >> clean cherry-picks. > >> > >> Simply making sure this patch does not bring a regression is very time consuming. > > > > Should I not bother submitting patches for such cleanups? > > > > I submitted another, more trivial patch, is it also considered unnecessary churn: > > > > --- > > > > Author: Vito Caputo > > Date: Sat Oct 12 17:10:41 2019 -0700 > > > > net: core: skbuff: skb_checksum_setup() drop err > > > > Return directly from all switch cases, no point in storing in err. > > > > Signed-off-by: Vito Caputo > > > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > index f5f904f46893..c59b68a413b5 100644 > > --- a/net/core/skbuff.c > > +++ b/net/core/skbuff.c > > @@ -4888,23 +4888,14 @@ static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate) > > */ > > int skb_checksum_setup(struct sk_buff *skb, bool recalculate) > > { > > - int err; > > - > > switch (skb->protocol) { > > case htons(ETH_P_IP): > > - err = skb_checksum_setup_ipv4(skb, recalculate); > > - break; > > - > > + return skb_checksum_setup_ipv4(skb, recalculate); > > case htons(ETH_P_IPV6): > > - err = skb_checksum_setup_ipv6(skb, recalculate); > > - break; > > - > > + return skb_checksum_setup_ipv6(skb, recalculate); > > default: > > - err = -EPROTO; > > - break; > > + return -EPROTO; > > } > > - > > - return err; > > } > > EXPORT_SYMBOL(skb_checksum_setup); > > > > --- > > > > Asking to calibrate my thresholds to yours, since I was planning to volunteer > > some time each evening to reading kernel code and submitting any obvious > > cleanups. > > > > This is not a cleanup. > > You prefer seeing the code written the way you did, but that is really a matter of taste. > I respectfully disagree with your assertion. When the diff --stat shows more lines removed than added without harming readability, preferably improving readability, it's both a cleanup and not a debatable matter of taste. Having the quantifiable metric of fewer lines of code matters. > Think about backports of real bug fixes to stable kernels. > That's fair, but when the change is an isolated mechanical one in a single small function, as the one quoted above - is that really of any significant burden on backports? > Having these re-writes of code make things less easy for us really. > So in general we tend to leave the existing code style. > > I already replied to the other patch submission, please read > > https://marc.info/?l=linux-netdev&m=157099669227635&w=2 > I read it, thank you for your responses. Do you have any guidance to offer someone wanting to contribute with 1-2 hours available per day? I don't want to cause a nuisance, but would like to help where I can. My flawed assumption was that small, isolated hygienic contributions without functionally changing anything would be appropriate. Thanks, Vito Caputo