netdev - Re: [PATCH net-next 6/6] net: bridge: avoid uselessly making offloaded ports promiscuous

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Message-ID: <20220409110444.5uf62kg5xjuvwysk@skbuf>
Date:   Sat, 9 Apr 2022 11:04:45 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     kernel test robot <lkp@...el.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        "kbuild-all@...ts.01.org" <kbuild-all@...ts.01.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Mattias Forsblad <mattias.forsblad@...il.com>
Subject: Re: [PATCH net-next 6/6] net: bridge: avoid uselessly making
 offloaded ports promiscuous

On Sat, Apr 09, 2022 at 06:17:15PM +0800, kernel test robot wrote:
> >> net/bridge/br_if.c:145:10: error: no member named 'offload_count' in 'struct net_bridge_port'
>                    if (p->offload_count) {
>                        ~  ^
>    130	/* When a port is added or removed or when certain port flags
>    131	 * change, this function is called to automatically manage
>    132	 * promiscuity setting of all the bridge ports.  We are always called
>    133	 * under RTNL so can skip using rcu primitives.
>    134	 */
>    135	void br_manage_promisc(struct net_bridge *br)
>    136	{
>    137		struct net_bridge_port *p;
>    138	
>    139		list_for_each_entry(p, &br->port_list, list) {
>    140			/* Offloaded ports have a separate address database for
>    141			 * forwarding, which is managed through switchdev and not
>    142			 * through dev_uc_add(), so the promiscuous concept makes no
>    143			 * sense for them. Avoid updating promiscuity in that case.
>    144			 */
>  > 145			if (p->offload_count) {

Good point. Please imagine there's a static inline nbp_get_offload_count()
that returns 0 when CONFIG_NET_SWITCHDEV=n. I'll address this for v2.

>    146				br_port_clear_promisc(p);
>    147				continue;
>    148			}
>    149	
>    150			/* If bridge is promiscuous, unconditionally place all ports
>    151			 * in promiscuous mode too. This allows the bridge device to
>    152			 * locally receive all unknown traffic.
>    153			 */
>    154			if (br->dev->flags & IFF_PROMISC) {
>    155				br_port_set_promisc(p);
>    156				continue;
>    157			}
>    158	
>    159			/* If vlan filtering is disabled, place all ports in
>    160			 * promiscuous mode.
>    161			 */
>    162			if (!br_vlan_enabled(br->dev)) {
>    163				br_port_set_promisc(p);
>    164				continue;
>    165			}
>    166	
>    167			/* If the number of auto-ports is <= 1, then all other ports
>    168			 * will have their output configuration statically specified
>    169			 * through fdbs. Since ingress on the auto-port becomes
>    170			 * forwarding/egress to other ports and egress configuration is
>    171			 * statically known, we can say that ingress configuration of
>    172			 * the auto-port is also statically known.
>    173			 * This lets us disable promiscuous mode and write this config
>    174			 * to hw.
>    175			 */
>    176			if (br->auto_cnt == 0 ||
>    177			    (br->auto_cnt == 1 && br_auto_port(p)))
>    178				br_port_clear_promisc(p);
>    179			else
>    180				br_port_set_promisc(p);
>    181		}
>    182	}
>    183