netdev - Re: [PATCH v4 net-next 02/11] net: bridge: add helper to retrieve the current ageing time

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Date:   Tue, 23 Mar 2021 12:36:40 +0200
From:   Nikolay Aleksandrov <nikolay@...dia.com>
To:     Vladimir Oltean <olteanv@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Roopa Prabhu <roopa@...dia.com>, Jiri Pirko <jiri@...nulli.us>,
        Ido Schimmel <idosch@...sch.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        UNGLinuxDriver@...rochip.com, Ivan Vecera <ivecera@...hat.com>,
        linux-omap@...r.kernel.org,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH v4 net-next 02/11] net: bridge: add helper to retrieve the
 current ageing time

On 23/03/2021 01:51, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@....com>
> 
> The SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME attribute is only emitted from:
> 
> sysfs/ioctl/netlink
> -> br_set_ageing_time
>    -> __set_ageing_time
> 
> therefore not at bridge port creation time, so:
> (a) switchdev drivers have to hardcode the initial value for the address
>     ageing time, because they didn't get any notification
> (b) that hardcoded value can be out of sync, if the user changes the
>     ageing time before enslaving the port to the bridge
> 
> We need a helper in the bridge, such that switchdev drivers can query
> the current value of the bridge ageing time when they start offloading
> it.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> Reviewed-by: Tobias Waldekranz <tobias@...dekranz.com>
> ---
>  include/linux/if_bridge.h |  6 ++++++
>  net/bridge/br_stp.c       | 13 +++++++++++++
>  2 files changed, 19 insertions(+)
> 

The patch is mostly fine, there are a few minor nits (const qualifiers). If there
is another version of the patch-set please add them, either way:

Acked-by: Nikolay Aleksandrov <nikolay@...dia.com>

> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
> index 920d3a02cc68..ebd16495459c 100644
> --- a/include/linux/if_bridge.h
> +++ b/include/linux/if_bridge.h
> @@ -137,6 +137,7 @@ struct net_device *br_fdb_find_port(const struct net_device *br_dev,
>  void br_fdb_clear_offload(const struct net_device *dev, u16 vid);
>  bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag);
>  u8 br_port_get_stp_state(const struct net_device *dev);
> +clock_t br_get_ageing_time(struct net_device *br_dev);
>  #else
>  static inline struct net_device *
>  br_fdb_find_port(const struct net_device *br_dev,
> @@ -160,6 +161,11 @@ static inline u8 br_port_get_stp_state(const struct net_device *dev)
>  {
>  	return BR_STATE_DISABLED;
>  }
> +
> +static inline clock_t br_get_ageing_time(struct net_device *br_dev)

const

> +{
> +	return 0;
> +}
>  #endif
>  
>  #endif
> diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
> index 86b5e05d3f21..3dafb6143cff 100644
> --- a/net/bridge/br_stp.c
> +++ b/net/bridge/br_stp.c
> @@ -639,6 +639,19 @@ int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
>  	return 0;
>  }
>  
> +clock_t br_get_ageing_time(struct net_device *br_dev)

const

> +{
> +	struct net_bridge *br;

const

> +
> +	if (!netif_is_bridge_master(br_dev))
> +		return 0;
> +
> +	br = netdev_priv(br_dev);
> +
> +	return jiffies_to_clock_t(br->ageing_time);
> +}
> +EXPORT_SYMBOL_GPL(br_get_ageing_time);
> +
>  /* called under bridge lock */
>  void __br_set_topology_change(struct net_bridge *br, unsigned char val)
>  {
>