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[2a01:cb0c:5:a600:3456:36f7:e65e:d1a0]) by smtp.gmail.com with ESMTPSA id g13sm10207487wro.84.2020.07.10.06.16.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2020 06:16:05 -0700 (PDT) Date: Fri, 10 Jul 2020 15:16:04 +0200 From: Olivier Matz To: Morten =?iso-8859-1?Q?Br=F8rup?= Cc: Hongzhi Guo , dev@dpdk.org, stable@dpdk.org, stephen@networkplumber.org, thomas@monjalon.net, konstantin.ananyev@intel.com, ferruh.yigit@intel.com, nicolas.chautru@intel.com, zhoujingbin@huawei.com, chenchanghu@huawei.com, jerry.lilijun@huawei.com, haifeng.lin@huawei.com Message-ID: <20200710131604.GB5869@platinum> References: <20200710065551.59352-1-guohongzhi1@huawei.com> <20200710124109.GY5869@platinum> <98CBD80474FA8B44BF855DF32C47DC35C61118@smartserver.smartshare.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35C61118@smartserver.smartshare.dk> User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [dpdk-dev] [PATCH] net: fix unneeded replacement of 0 by ffff for TCP checksum X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Fri, Jul 10, 2020 at 03:10:34PM +0200, Morten Brørup wrote: > > From: Olivier Matz [mailto:olivier.matz@6wind.com] > > Sent: Friday, July 10, 2020 2:41 PM > > > > On Fri, Jul 10, 2020 at 02:55:51PM +0800, Hongzhi Guo wrote: > > > Per RFC768: > > > If the computed checksum is zero, it is transmitted as all ones. > > > An all zero transmitted checksum value means that the transmitter > > > generated no checksum. > > > > > > RFC793 for TCP has no such special treatment for the checksum of > > zero. > > > > > > Fixes: 6006818cfb26 ("net: new checksum functions") > > > Cc: stable@dpdk.org > > > > > > Signed-off-by: Hongzhi Guo > > > --- > > > v2: > > > * Fixed commit tile > > > * Fixed the API comment > > > --- > > > --- > > > lib/librte_net/rte_ip.h | 18 +++++++++++++++--- > > > 1 file changed, 15 insertions(+), 3 deletions(-) > > > > > > diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h > > > index 292f63fd7..d03c77120 100644 > > > --- a/lib/librte_net/rte_ip.h > > > +++ b/lib/librte_net/rte_ip.h > > > @@ -325,7 +325,7 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr > > *ipv4_hdr, uint64_t ol_flags) > > > * The pointer to the beginning of the L4 header. > > > * @return > > > * The complemented checksum to set in the IP packet > > > - * or 0 on error > > > + * or 0 if the IP length is invalid in the header. > > > */ > > > static inline uint16_t > > > rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const > > void *l4_hdr) > > 0 is a valid return value, so I suggest omitting it from the return value description: > > * @return > - * The complemented checksum to set in the IP packet > - * or 0 on error > + * The complemented checksum to set in the IP packet. > > The comparison "if (l3_len < sizeof(struct rte_ipv4_hdr))" is only there to protect against invalid input; it prevents l4_len from becoming negative. I don't get why "0 if the IP length is invalid in the header" should be removed from the comment: 0 is both a valid return value and the value returned on invalid packet. > For the same reason, unlikely() should be added to this comparison. Maybe yes, but that's another story I think. > Otherwise, > > Acked-by: Morten Brørup >