Subject: Re: [PATCH 2/7] bridge: Keep track of ports capable of flooding.

From: Vlad Yasevich <[email-masked]>
Date: Wed, 26 Feb 2014 10:41:57 -0500

On 02/26/2014 10:41 AM, Michael S. Tsirkin wrote:
> On Wed, Feb 26, 2014 at 10:18:20AM -0500, Vlad Yasevich wrote:
>> Keep track of bridge ports that have unicast flooding turned on.
>> This will later be used by the algorithm to automatically manage
>> address programming and promisc mode.
>>
>> Signed-off-by: Vlad Yasevich <[email-masked]>
>> ---
>>  net/bridge/br_if.c       | 60 ++++++++++++++++++++++++++++++++++++++++++++++--
>>  net/bridge/br_netlink.c  |  3 +++
>>  net/bridge/br_private.h  |  4 ++++
>>  net/bridge/br_sysfs_if.c |  6 ++++-
>>  4 files changed, 70 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>> index 54d207d..f072b34 100644
>> --- a/net/bridge/br_if.c
>> +++ b/net/bridge/br_if.c
>> @@ -27,6 +27,9 @@
>>  
>>  #include "br_private.h"
>>  
>> +static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br);
>> +static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br);
>> +
> 
> same nitpick about forward declarations of static
> functions.
> maybe they are ok for bridge, but that's my $.02
> 

Ok.  Will take a look. Just means that I might need to re-order the
code which may scatter it a bit through the file.

> 
>>  /*
>>   * Determine initial path cost based on speed.
>>   * using recommendations from 802.1d standard
>> @@ -141,11 +144,14 @@ static void del_nbp(struct net_bridge_port *p)
>>  
>>  	br_ifinfo_notify(RTM_DELLINK, p);
>>  
>> +	list_del_rcu(&p->list);
>> +
>> +	if (p->flags & BR_FLOOD)
>> +		br_del_flood_port(p, br);
>> +
>>  	nbp_vlan_flush(p);
>>  	br_fdb_delete_by_port(br, p, 1);
>>  
>> -	list_del_rcu(&p->list);
>> -
>>  	dev->priv_flags &= ~IFF_BRIDGE_PORT;
>>  
>>  	netdev_rx_handler_unregister(dev);
> 
> ok so it doesn't matter in which order we do
> list_del_rcu and nbp_vlan_flush then?

Nope.  vlan_flush knows which port its working and doesn't touch
the port list.

What does touch the port list if br_fdb_delete_by_port, but that only
touches it in fdb_delete_local(), and it's ok there since we are trying
to point an existing fdb out a different port.

Thanks
-vlad

> 
>> @@ -383,6 +389,9 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
>>  	dev_disable_lro(dev);
>>  
>>  	list_add_rcu(&p->list, &br->port_list);
>> +
>> +	if (p->flags & BR_FLOOD)
>> +		br_add_flood_port(p, br);
>>  
>>  	netdev_update_features(br->dev);
>>  
>> @@ -455,3 +464,50 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
>>  
>>  	return 0;
>>  }
>> +
>> +static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>> +{
>> +	/* Increment the number of  flooding ports, and if we
>> +	 * only have 1 flooding port cache if for future use.
>> +	 */
>> +	br->n_flood_ports++;
>> +	if (br->n_flood_ports == 1)
>> +		br->c_flood_port = p;
>> +}
>> +
>> +static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>> +{
>> +	struct net_bridge_port *port;
>> +
>> +	/* Decrement the  number of flood port.
>> +	 * If we are deleting the current flood port, clear
>> +	 * the cached port.  If we are down to 1 flood port,
>> +	 * set it if it is not set.
>> +	 */
>> +	br->n_flood_ports--;
>> +	if (p == br->c_flood_port)
>> +		br->c_flood_port = NULL;
>> +
>> +	if (br->n_flood_ports == 1) {
>> +		list_for_each_entry(port, &p->br->port_list, list) {
>> +			if (port->flags & BR_FLOOD) {
>> +				br->c_flood_port = port;
>> +				break;
>> +			}
>> +		}
>> +	}
>> +}
>> +
>> +void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
>> +{
>> +	struct net_bridge *br = p->br;
>> +
>> +	/* We are only interested FLOOD flag */
>> +	if (!(mask & BR_FLOOD))
>> +		return;
>> +
>> +	if (p->flags & BR_FLOOD)
>> +		br_add_flood_port(p, br);
>> +	else
>> +		br_del_flood_port(p, br);
>> +}
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index e74b6d53..01382b9 100644
>> --- a/net/bridge/br_netlink.c
>> +++ b/net/bridge/br_netlink.c
>> @@ -328,6 +328,7 @@ static void br_set_port_flag(struct net_bridge_port *p, struct nlattr *tb[],
>>  static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
>>  {
>>  	int err;
>> +	unsigned long old_flags = p->flags;
>>  
>>  	br_set_port_flag(p, tb, IFLA_BRPORT_MODE, BR_HAIRPIN_MODE);
>>  	br_set_port_flag(p, tb, IFLA_BRPORT_GUARD, BR_BPDU_GUARD);
>> @@ -353,6 +354,8 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
>>  		if (err)
>>  			return err;
>>  	}
>> +
>> +	br_port_flags_change(p, old_flags ^ p->flags);
>>  	return 0;
>>  }
>>  
>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>> index 3ba11bc..26a3987 100644
>> --- a/net/bridge/br_private.h
>> +++ b/net/bridge/br_private.h
>> @@ -290,6 +290,8 @@ struct net_bridge
>>  	struct timer_list		topology_change_timer;
>>  	struct timer_list		gc_timer;
>>  	struct kobject			*ifobj;
>> +	struct net_bridge_port		*c_flood_port;
>> +	u32				n_flood_ports;
> 
> any hints on locking for these fields?
> are these all under rtnl?
> 
>>  #ifdef CONFIG_BRIDGE_VLAN_FILTERING
>>  	u8				vlan_enabled;
>>  	struct net_port_vlans __rcu	*vlan_info;
>> @@ -415,6 +417,8 @@ int br_del_if(struct net_bridge *br, struct net_device *dev);
>>  int br_min_mtu(const struct net_bridge *br);
>>  netdev_features_t br_features_recompute(struct net_bridge *br,
>>  					netdev_features_t features);
>> +void br_port_flags_change(struct net_bridge_port *port,
>> +			  unsigned long mask);
>>  
>>  /* br_input.c */
>>  int br_handle_frame_finish(struct sk_buff *skb);
>> diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
>> index 7f66aa4..9ff6691 100644
>> --- a/net/bridge/br_sysfs_if.c
>> +++ b/net/bridge/br_sysfs_if.c
>> @@ -51,7 +51,10 @@ static BRPORT_ATTR(_name, S_IRUGO | S_IWUSR,			\
>>  static int store_flag(struct net_bridge_port *p, unsigned long v,
>>  		     unsigned long mask)
>>  {
>> -	unsigned long flags = p->flags;
>> +	unsigned long flags;
>> +	unsigned long old_flags;
>> +
>> +	old_flags = flags = p->flags;
>>  
>>  	if (v)
>>  		flags |= mask;
>> @@ -60,6 +63,7 @@ static int store_flag(struct net_bridge_port *p, unsigned long v,
>>  
>>  	if (flags != p->flags) {
>>  		p->flags = flags;
>> +		br_port_flags_change(p, old_flags ^ flags);
>>  		br_ifinfo_notify(RTM_NEWLINK, p);
>>  	}
>>  	return 0;
>> -- 
>> 1.8.5.3