lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 19 Jul 2021 10:20:13 +0200 From: Lino Sanfilippo <LinoSanfilippo@....de> To: Vladimir Oltean <olteanv@...il.com> Cc: Andrew Lunn <andrew@...n.ch>, woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com, vivien.didelot@...il.com, f.fainelli@...il.com, davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Aw: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum Hi, > Gesendet: Donnerstag, 15. Juli 2021 um 16:36 Uhr > Von: "Vladimir Oltean" <olteanv@...il.com> > An: "Andrew Lunn" <andrew@...n.ch> > Cc: "Lino Sanfilippo" <LinoSanfilippo@....de>, woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com, vivien.didelot@...il.com, f.fainelli@...il.com, davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org > Betreff: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum > > On Thu, Jul 15, 2021 at 03:08:53PM +0200, Andrew Lunn wrote: > > > - If we inherit NETIF_F_HW_CSUM from the master for tail taggers, it is > > > actively detrimential to keep this feature enabled, as proven my Lino. > > > As for header taggers, I fail to see how this would be helpful, since > > > the DSA master would always fail to see the real IP header (it has > > > been pushed to the right by the DSA tag), and therefore, the DSA > > > master offload would be effectively bypassed. > > > > The Marvell MACs know about DSA and should be able to perform hardware > > checksumming. It is a long time since i looked at how this works, but > > i think there is a field in the descriptor which gets set with the > > offset to the IP header, so it work for DSA as well as EDSA. > > > > I _think_ Broadcom MACs also know about Broadcom tags and can do the > > right thing. > > > > So we need to be a bit careful here to prevent performance regressions > > for same vendor MAC+Switch combinations. > > Tell me more (show me some code). Do Marvell Ethernet controllers which > support TX checksumming with Marvell switches do different things > depending on whether DSA or EDSA is used? Because we can currently > toggle between DSA and EDSA at runtime. > > This new information means we can only accept Lino's patch 2/2 as-is for > the "net" tree, otherwise we will introduce regressions one way or > another. It will only be a partial fix for the particular case of KSZ > switches which probably have no DSA master counterpart to support TX > checksumming. > Should I then resend the series with patch 1 handling the NETIF_F_SG and NETIF_F_FRAGLIST flags (i.e. deleting them if tailroom is needed) in dsa_slave_setup_tagger() as you suggested and patch 2 as it is? Regards, Lino
Powered by blists - more mailing lists