netdev - Re: [PATCH v4 net-next 01/14] net: bridge: switchdev: send FDB notifications for host addresses

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Message-ID: <984a649e-38fb-9962-e7dd-3cd441a83ec9@nvidia.com>
Date:   Tue, 29 Jun 2021 13:40:20 +0300
From:   Nikolay Aleksandrov <nikolay@...dia.com>
To:     Vladimir Oltean <olteanv@...il.com>, netdev@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ido Schimmel <idosch@...sch.org>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH v4 net-next 01/14] net: bridge: switchdev: send FDB
 notifications for host addresses

On 29/06/2021 00:59, Vladimir Oltean wrote:
> From: Tobias Waldekranz <tobias@...dekranz.com>
> 
> Treat addresses added to the bridge itself in the same way as regular
> ports and send out a notification so that drivers may sync it down to
> the hardware FDB.
> 
> Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> ---
>  net/bridge/br_fdb.c       |  4 ++--
>  net/bridge/br_private.h   |  7 ++++---
>  net/bridge/br_switchdev.c | 11 +++++------
>  3 files changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index 16f9434fdb5d..0296d737a519 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -602,7 +602,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
>  			/* fastpath: update of existing entry */
>  			if (unlikely(source != fdb->dst &&
>  				     !test_bit(BR_FDB_STICKY, &fdb->flags))) {
> -				br_switchdev_fdb_notify(fdb, RTM_DELNEIGH);
> +				br_switchdev_fdb_notify(br, fdb, RTM_DELNEIGH);
>  				fdb->dst = source;
>  				fdb_modified = true;
>  				/* Take over HW learned entry */
> @@ -794,7 +794,7 @@ static void fdb_notify(struct net_bridge *br,
>  	int err = -ENOBUFS;
>  
>  	if (swdev_notify)
> -		br_switchdev_fdb_notify(fdb, type);
> +		br_switchdev_fdb_notify(br, fdb, type);
>  
>  	skb = nlmsg_new(fdb_nlmsg_size(), GFP_ATOMIC);
>  	if (skb == NULL)
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index a684d0cfc58c..2b48b204205e 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -1654,8 +1654,8 @@ int br_switchdev_set_port_flag(struct net_bridge_port *p,
>  			       unsigned long flags,
>  			       unsigned long mask,
>  			       struct netlink_ext_ack *extack);
> -void br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb,
> -			     int type);
> +void br_switchdev_fdb_notify(struct net_bridge *br,
> +			     const struct net_bridge_fdb_entry *fdb, int type);
>  int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid, u16 flags,
>  			       struct netlink_ext_ack *extack);
>  int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid);
> @@ -1702,7 +1702,8 @@ static inline int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid)
>  }
>  
>  static inline void
> -br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
> +br_switchdev_fdb_notify(struct net_bridge *br,
> +			const struct net_bridge_fdb_entry *fdb, int type)
>  {
>  }
>  
> diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> index a5e601e41cb9..9a707da79dfe 100644
> --- a/net/bridge/br_switchdev.c
> +++ b/net/bridge/br_switchdev.c
> @@ -108,7 +108,8 @@ int br_switchdev_set_port_flag(struct net_bridge_port *p,
>  }
>  
>  void
> -br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
> +br_switchdev_fdb_notify(struct net_bridge *br,
> +			const struct net_bridge_fdb_entry *fdb, int type)
>  {
>  	struct switchdev_notifier_fdb_info info = {
>  		.addr = fdb->key.addr.addr,
> @@ -117,18 +118,16 @@ br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
>  		.is_local = test_bit(BR_FDB_LOCAL, &fdb->flags),
>  		.offloaded = test_bit(BR_FDB_OFFLOADED, &fdb->flags),
>  	};
> -
> -	if (!fdb->dst)
> -		return;
> +	struct net_device *dev = fdb->dst ? fdb->dst->dev : br->dev;

you should use READ_ONCE() for fdb->dst here to make sure it's read only once,
to be fair the old code had the same issue :)

>  
>  	switch (type) {
>  	case RTM_DELNEIGH:
>  		call_switchdev_notifiers(SWITCHDEV_FDB_DEL_TO_DEVICE,
> -					 fdb->dst->dev, &info.info, NULL);
> +					 dev, &info.info, NULL);
>  		break;
>  	case RTM_NEWNEIGH:
>  		call_switchdev_notifiers(SWITCHDEV_FDB_ADD_TO_DEVICE,
> -					 fdb->dst->dev, &info.info, NULL);
> +					 dev, &info.info, NULL);
>  		break;
>  	}
>  }
>