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Date: Mon, 23 Aug 2021 03:31:32 +0300 From: Vladimir Oltean <olteanv@...il.com> To: Alvin Šipraga <ALSI@...g-olufsen.dk> Cc: Alvin Šipraga <alvin@...s.dk>, Linus Walleij <linus.walleij@...aro.org>, Andrew Lunn <andrew@...n.ch>, Vivien Didelot <vivien.didelot@...il.com>, Florian Fainelli <f.fainelli@...il.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Rob Herring <robh+dt@...nel.org>, Heiner Kallweit <hkallweit1@...il.com>, Russell King <linux@...linux.org.uk>, Michael Rasmussen <MIR@...g-olufsen.dk>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RFC PATCH net-next 3/5] net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag On Mon, Aug 23, 2021 at 12:28:51AM +0000, Alvin Šipraga wrote: > On 8/23/21 1:45 AM, Vladimir Oltean wrote: > > On Sun, Aug 22, 2021 at 11:37:28PM +0000, Alvin Šipraga wrote: > >>>>>> + skb->offload_fwd_mark = 1; > >>>>> > >>>>> At the very least, please use > >>>>> > >>>>> dsa_default_offload_fwd_mark(skb); > >>>>> > >>>>> which does the right thing when the port is not offloading the bridge. > >>>> > >>>> Sure. Can you elaborate on what you mean by "at the very least"? Can it > >>>> be improved even further? > >>> > >>> The elaboration is right below. skb->offload_fwd_mark should be set to > >>> zero for packets that have been forwarded only to the host (like packets > >>> that have hit a trapping rule). I guess the switch will denote this > >>> piece of info through the REASON code. > >> > >> Yes, I think it will be communicated in REASON too. I haven't gotten to > >> deciphering the contents of this field since it has not been needed so > >> far: the ports are fully isolated and all bridging is done in software. > > > > In that case, setting skb->offload_fwd_mark to true is absolutely wrong, > > since the bridge is told that no software forwarding should be done > > between ports, as it was already done in hardware (see nbp_switchdev_allowed_egress). > > > > I wonder how this has ever worked? Are you completely sure that bridging > > is done in software? > > You are absolutely right, and indeed I checked just now and the bridging > is not working at all. > > Deleting the line (i.e. skb->offload_fwd_mark = 0) restores the expected > bridging behaviour. > > Based on what you have said, do I understand correctly that > offload_fwd_mark shouldn't be set until bridge hardware offloading has > been implemented? > > Thanks for your detailed review so far. So back to my initial suggestion: | At the very least, please use | | dsa_default_offload_fwd_mark(skb); | | which does the right thing when the port is not offloading the bridge. This way, you won't have to touch this code even after you start implementing .port_bridge_join and .port_bridge_leave. It deals with both cases.
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