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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 92440C4360C for ; Sun, 13 Oct 2019 20:17:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 687BA20663 for ; Sun, 13 Oct 2019 20:17:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728916AbfJMURR (ORCPT ); Sun, 13 Oct 2019 16:17:17 -0400 Received: from shells.gnugeneration.com ([66.240.222.126]:41972 "EHLO shells.gnugeneration.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726264AbfJMURR (ORCPT ); Sun, 13 Oct 2019 16:17:17 -0400 Received: by shells.gnugeneration.com (Postfix, from userid 1000) id 0660D1A40559; Sun, 13 Oct 2019 13:17:16 -0700 (PDT) Date: Sun, 13 Oct 2019 13:17:16 -0700 From: Vito Caputo To: Eric Dumazet Cc: davem@davemloft.net, netdev@vger.kernel.org Subject: Re: [PATCH] net: core: skbuff: skb_checksum_setup() drop err Message-ID: <20191013201716.dwxfbr5kbueexomw@shells.gnugeneration.com> References: <20191013003053.tmdc3hs73ik3asxq@shells.gnugeneration.com> <52dfe9f3-cc54-408d-6781-3bc0a86ebae8@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52dfe9f3-cc54-408d-6781-3bc0a86ebae8@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 12:58:04PM -0700, Eric Dumazet wrote: > > > On 10/12/19 5:30 PM, Vito Caputo wrote: > > Return directly from all switch cases, no point in storing in err. > > > > Signed-off-by: Vito Caputo > > --- > > net/core/skbuff.c | 15 +++------------ > > 1 file changed, 3 insertions(+), 12 deletions(-) > > > > 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); > > > We prefer having a single return point in a function, if possible. > > The err variable would make easier for debugging support, > if say a developer needs to trace this function. > Except there are examples under net/core of precisely this pattern, e.g.: --- __be32 flow_get_u32_src(const struct flow_keys *flow) { switch (flow->control.addr_type) { case FLOW_DISSECTOR_KEY_IPV4_ADDRS: return flow->addrs.v4addrs.src; case FLOW_DISSECTOR_KEY_IPV6_ADDRS: return (__force __be32)ipv6_addr_hash( &flow->addrs.v6addrs.src); case FLOW_DISSECTOR_KEY_TIPC: return flow->addrs.tipckey.key; default: return 0; } } EXPORT_SYMBOL(flow_get_u32_src); __be32 flow_get_u32_dst(const struct flow_keys *flow) { switch (flow->control.addr_type) { case FLOW_DISSECTOR_KEY_IPV4_ADDRS: return flow->addrs.v4addrs.dst; case FLOW_DISSECTOR_KEY_IPV6_ADDRS: return (__force __be32)ipv6_addr_hash( &flow->addrs.v6addrs.dst); default: return 0; } } EXPORT_SYMBOL(flow_get_u32_dst); --- This compact form of mapping is found throughout the kernel, is skb_checksum_setup() special? Regards, Vito Caputo