From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] net: sungem: fix rx checksum support Date: Wed, 20 Jun 2018 14:30:50 +0900 (KST) Message-ID: <20180620.143050.313454768369559179.davem@davemloft.net> References: <20180620021850.211683-1-edumazet@google.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, mroos@linux.ee, malat@debian.org, schwab@linux-m68k.org, eric.dumazet@gmail.com To: edumazet@google.com Return-path: Received: from shards.monkeyblae.net ([23.128.96.9]:55368 "EHLO shards.monkeyblade.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752725AbeFTFaz (ORCPT ); Wed, 20 Jun 2018 01:30:55 -0400 In-Reply-To: <20180620021850.211683-1-edumazet@google.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Date: Tue, 19 Jun 2018 19:18:50 -0700 > After commit 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE > are friends"), sungem owners reported the infamous "eth0: hw csum failure" > message. > > CHECKSUM_COMPLETE has in fact never worked for this driver, but this > was masked by the fact that upper stacks had to strip the FCS, and > therefore skb->ip_summed was set back to CHECKSUM_NONE before > my recent change. > > Driver configures a number of bytes to skip when the chip computes > the checksum, and for some reason only half of the Ethernet header > was skipped. > > Then a second problem is that we should strip the FCS by default, > unless the driver is updated to eventually support NETIF_F_RXFCS in > the future. > > Finally, a driver should check if NETIF_F_RXCSUM feature is enabled > or not, so that the admin can turn off rx checksum if wanted. > > Many thanks to Andreas Schwab and Mathieu Malaterre for their > help in debugging this issue. > > Signed-off-by: Eric Dumazet > Reported-by: Meelis Roos > Reported-by: Mathieu Malaterre > Reported-by: Andreas Schwab > Tested-by: Andreas Schwab Applied and queued up for -stable, thanks Eric.