Subject: Re: [PATCH 4/7] bridge: Automatically manage port promiscuous mode.

From: Vlad Yasevich <[email-masked]>
Date: Wed, 26 Feb 2014 11:02:17 -0500

On 02/26/2014 10:51 AM, Michael S. Tsirkin wrote:
> On Wed, Feb 26, 2014 at 10:18:22AM -0500, Vlad Yasevich wrote:
>> When there is only 1 flooding port, this port is programmed
>> with all the address
> 
> all the addresses?

All statically configured ones plus locals.
Locals are needed preserve the bridge behavior of
being able to receive packets addresses to any of the
ports mac addresses on any interface.
This actually cuts the usability of this feature
in about half. :(

> 
>> the bridge accumulated.  This allows
>> us to place this port into non-promiscuous mode.
>> At other times, all ports are set as promiscuous.  To help
>> track whether the bridge set the mode or not, a new
>> flag is introduced.
>>
>> Signed-off-by: Vlad Yasevich <[email-masked]>
>> ---
>>  net/bridge/br_if.c      | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
>>  net/bridge/br_private.h |  1 +
>>  2 files changed, 47 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>> index e782c2e..51df642 100644
>> --- a/net/bridge/br_if.c
>> +++ b/net/bridge/br_if.c
>> @@ -136,7 +136,7 @@ static void del_nbp(struct net_bridge_port *p)
>>  
>>  	sysfs_remove_link(br->ifobj, p->dev->name);
>>  
>> -	dev_set_promiscuity(dev, -1);
>> +	dev_set_allmulti(dev, -1);
>>  
>>  	spin_lock_bh(&br->lock);
>>  	br_stp_disable_port(p);
>> @@ -359,7 +359,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
>>  
>>  	call_netdevice_notifiers(NETDEV_JOIN, dev);
>>  
>> -	err = dev_set_promiscuity(dev, 1);
>> +	err = dev_set_allmulti(dev, 1);
>>  	if (err)
>>  		goto put_back;
>>  
>> @@ -465,6 +465,48 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
>>  	return 0;
>>  }
>>  
>> +static int br_port_set_promisc(struct net_bridge_port *p)
>> +{
>> +	int err = 0;
>> +
>> +	if (p->flags & BR_PROMISC)
>> +		return err;
>> +
>> +	err = dev_set_promiscuity(p->dev, 1);
>> +	if (err)
>> +		return err;
>> +
>> +	p->flags |= BR_PROMISC;
>> +	return err;
>> +}
>> +
> 
> you take pains to return an error code here,
> only to ignore it in the caller?

You are right.  This can be turned to void.

> 
>> +static void br_port_clear_promisc(struct net_bridge_port *p)
>> +{
>> +	if (!(p->flags & BR_PROMISC))
>> +		return;
>> +
>> +	dev_set_promiscuity(p->dev, -1);
>> +	p->flags &= ~BR_PROMISC;
>> +}
>> +
>> +/* When a port is added or removed or when the flooding status of
>> + * the port changes, this function is called to automatically mange
>> + * promiscuity setting of all the bridge ports.  We are always called
>> + * under RTNL so can skip using rcu primitives.
>> + */
>> +static void br_manage_promisc(struct net_bridge *br)
>> +{
>> +	struct net_bridge_port *p;
>> +
>> +	list_for_each_entry(p, &br->port_list, list) {
>> +		if (!br_port_exists(p->dev) ||
>> +		    (br->n_flood_ports == 1 && br->c_flood_port == p))
>> +			br_port_clear_promisc(p);
>> +		else
>> +			br_port_set_promisc(p);
>> +	}
>> +}
>> +
>>  static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>>  {
>>  	/* Increment the number of  flooding ports, and if we
>> @@ -475,6 +517,7 @@ static void br_add_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>>  		br->c_flood_port = p;
>>  
>>  	br_fdb_addrs_sync(br);
>> +	br_manage_promisc(br);
>>  }
>>  
>>  static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>> @@ -502,6 +545,7 @@ static void br_del_flood_port(struct net_bridge_port *p, struct net_bridge *br)
>>  			}
>>  		}
>>  	}
>> +	br_manage_promisc(br);
>>  }
>>  
>>  void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>> index 40a6927..6670cb3 100644
>> --- a/net/bridge/br_private.h
>> +++ b/net/bridge/br_private.h
>> @@ -174,6 +174,7 @@ struct net_bridge_port
>>  #define BR_ADMIN_COST		0x00000010
>>  #define BR_LEARNING		0x00000020
>>  #define BR_FLOOD		0x00000040
>> +#define BR_PROMISC		0x00000080
>>
> 
> Considering you then have a separate logic in 7/7
> will this be cleaner as a per-port flag?

It is a per-port flag here.  I can change it to
BR_PORT_PROMISC to make it clearer.

-vlad

>   
>>  #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
>>  	struct bridge_mcast_query	ip4_query;
>> -- 
>> 1.8.5.3