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Date: Wed, 30 Apr 2014 09:47:37 -0400
From: Vlad Yasevich <vyasevich@...il.com>
To: "Michael S. Tsirkin" <mst@...hat.com>,
Vlad Yasevich <vyasevic@...hat.com>
CC: netdev@...r.kernel.org, bridge@...ts.linux-foundation.org,
shemminger@...tta.com, jhs@...atatu.com, john.r.fastabend@...el.com
Subject: Re: [RFC PATCH v2 net-next 2/7] bridge: Keep track of ports capable
of automatic discovery.
On 04/30/2014 06:18 AM, Michael S. Tsirkin wrote:
> On Tue, Apr 29, 2014 at 05:20:23PM -0400, Vlad Yasevich wrote:
>> By default, ports on the bridge are capable of automatic
>> discovery of nodes located behind the port. This is accomplished
>> via flooding of unknown traffic (BR_FLOOD) and learning the
>> mac addresses from these packets (BR_LEARNING).
>> If the above functionality is diabled by turning off these
>> flags, the port requires static configuration in the form
>> of static FDB entries to function properly.
>>
>> This patch adds functionality to keep track of all ports
>> capable of automatic discovery. This will later be used
>> to control promiscuity settings.
>>
>> Signed-off-by: Vlad Yasevich <vyasevic@...hat.com>
>> ---
>> net/bridge/br_if.c | 27 +++++++++++++++++++++++++++
>> net/bridge/br_netlink.c | 3 +++
>> net/bridge/br_private.h | 6 ++++++
>> net/bridge/br_sysfs_if.c | 6 +++++-
>> 4 files changed, 41 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>> index 5262b86..7e60c4c 100644
>> --- a/net/bridge/br_if.c
>> +++ b/net/bridge/br_if.c
>> @@ -85,6 +85,18 @@ void br_port_carrier_check(struct net_bridge_port *p)
>> spin_unlock_bh(&br->lock);
>> }
>>
>> +static void nbp_update_port_count(struct net_bridge *br)
>> +{
>> + struct net_bridge_port *p;
>> + u32 cnt = 0;
>> +
>> + list_for_each_entry(p, &br->port_list, list) {
>> + if (br_is_auto_port(p))
>> + cnt++;
>> + }
>> + br->auto_cnt = cnt;
>> +}
>> +
>> static void release_nbp(struct kobject *kobj)
>> {
>> struct net_bridge_port *p
>> @@ -146,6 +158,8 @@ static void del_nbp(struct net_bridge_port *p)
>>
>> list_del_rcu(&p->list);
>>
>> + nbp_update_port_count(br);
>> +
>> dev->priv_flags &= ~IFF_BRIDGE_PORT;
>>
>> netdev_rx_handler_unregister(dev);
>> @@ -384,6 +398,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
>>
>> list_add_rcu(&p->list, &br->port_list);
>>
>> + nbp_update_port_count(br);
>> +
>> netdev_update_features(br->dev);
>>
>> if (br->dev->needed_headroom < dev->needed_headroom)
>> @@ -455,3 +471,14 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
>>
>> return 0;
>> }
>> +
>> +void br_port_flags_change(struct net_bridge_port *p, unsigned long old_flags)
>> +{
>> + struct net_bridge *br = p->br;
>> + unsigned long mask = old_flags ^ p->flags;
>> +
>> + if (!(mask & BR_AUTO_MASK))
>> + return;
>> +
>> + nbp_update_port_count(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 06811d7..db714a1 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_AUTO_MASK (BR_FLOOD | BR_LEARNING)
>>
>> #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
>> struct bridge_mcast_query ip4_query;
>> @@ -198,6 +199,8 @@ struct net_bridge_port
>> #endif
>> };
>>
>> +#define br_is_auto_port(p) (((p)->flags & BR_AUTO_MASK) == BR_AUTO_MASK)
>> +
>
> I think you
> really want ((p)->flags & BR_AUTO_MASK) instead without
> == BR_AUTO_MASK.
>
> For example if learning is off but flood is on, things work
> (slowly) automatically without configuring static entries.
>
> OTOH if flood is off but learning is on, a bunch of packets
> might get dropped but eventually you might learn the
> mac and then networking will start working.
>
Yes, you are completely correct. I flipped the meaning of the
macro, but forgot to account correctly for it.
static == not flooding && not learning.
auto != static.
The reason I count "auto" ports is so I only have to keep 1 counter
around. If I counted static, I'd also have to count all ports as well.
Not much of a difference, but it's one less counter.
Fill fix.
Thanks
-vlad
>
>> #define br_port_exists(dev) (dev->priv_flags & IFF_BRIDGE_PORT)
>>
>> static inline struct net_bridge_port *br_port_get_rcu(const struct net_device *dev)
>> @@ -290,6 +293,7 @@ struct net_bridge
>> struct timer_list topology_change_timer;
>> struct timer_list gc_timer;
>> struct kobject *ifobj;
>> + u32 auto_cnt;
>> #ifdef CONFIG_BRIDGE_VLAN_FILTERING
>> u8 vlan_enabled;
>> struct net_port_vlans __rcu *vlan_info;
>> @@ -415,6 +419,8 @@ 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 old_flags);
>>
>> /* 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 112a25e..58c26e3 100644
>> --- a/net/bridge/br_sysfs_if.c
>> +++ b/net/bridge/br_sysfs_if.c
>> @@ -49,7 +49,10 @@ 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;
>> @@ -58,6 +61,7 @@ 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;
>> --
>> 1.9.0
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