Re: [patch net-next v3 09/17] bridge: add API to notify bridge driver of learned FBD on offloaded device

Andy Gospodarek
2014-11-25T16:39:01Z

On Tue, Nov 25, 2014 at 11:28:40AM +0100, Jiri Pirko wrote:
> From: Scott Feldman <sfeldma@gmail.com>
>
> When the swdev device learns a new mac/vlan on a port, it sends some async
> notification to the driver and the driver installs an FDB in the device.
> To give a holistic system view, the learned mac/vlan should be reflected
> in the bridge's FBD table, so the user, using normal iproute2 cmds, can view
> what is currently learned by the device. This API on the bridge driver gives
> a way for the swdev driver to install an FBD entry in the bridge FBD table.
> (And remove one).
>
> This is equivalent to the device running these cmds:
>
> bridge fdb [add|del] <mac> dev <dev> vid <vlan id> master
>
> This patch needs some extra eyeballs for review, in paricular around the
> locking and contexts.
>
> Signed-off-by: Scott Feldman <sfeldma@gmail.com>
> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
> ---
> v2->v3:
> -added "external" word into function names to emphasize fdbs are learned
> externally
> -added "added_by_external_learn" to fbd entry struct indicate the entry
> was learned externaly and build some logic around that
> -expose the fact that fdb entry was learned externally to userspace
> v1->v2:
> -no change
> ---
> include/linux/if_bridge.h | 18 +++++++++
> include/uapi/linux/neighbour.h | 1 +
> net/bridge/br_fdb.c | 91 +++++++++++++++++++++++++++++++++++++++++-
> net/bridge/br_private.h | 1 +
> 4 files changed, 110 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
> index 808dcb8..fa2eca6 100644
> --- a/include/linux/if_bridge.h
> +++ b/include/linux/if_bridge.h
> @@ -37,6 +37,24 @@ extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __use
> typedef int br_should_route_hook_t(struct sk_buff *skb);
> extern br_should_route_hook_t __rcu *br_should_route_hook;
>
> +#if IS_ENABLED(CONFIG_BRIDGE)
> +int br_fdb_external_learn_add(struct net_device *dev,
> + const unsigned char *addr, u16 vid);
> +int br_fdb_external_learn_del(struct net_device *dev,
> + const unsigned char *addr, u16 vid);
> +#else
> +static inline int br_fdb_external_learn_add(struct net_device *dev,
> + const unsigned char *addr, u16 vid)
> +{
> + return 0;
> +}
> +static inline int br_fdb_external_learn_del(struct net_device *dev,
> + const unsigned char *addr, u16 vid)
> +{
> + return 0;
> +}
> +#endif
> +
> #if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING)
> int br_multicast_list_adjacent(struct net_device *dev,
> struct list_head *br_ip_list);
> diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
> index 4a1d7e9..3a9b0df 100644
> --- a/include/uapi/linux/neighbour.h
> +++ b/include/uapi/linux/neighbour.h
> @@ -40,6 +40,7 @@ enum {
>
> #define NTF_SELF 0x02
> #define NTF_MASTER 0x04
> +#define NTF_EXT_LEARNED 0x10
>
> /*
> * Neighbor Cache Entry States.
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index b1be971..b42e71d 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -481,6 +481,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
> fdb->is_local = 0;
> fdb->is_static = 0;
> fdb->added_by_user = 0;
> + fdb->added_by_external_learn = 0;
> fdb->updated = fdb->used = jiffies;
> hlist_add_head_rcu(&fdb->hlist, head);
> }
> @@ -613,7 +614,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
> ndm->ndm_family = AF_BRIDGE;
> ndm->ndm_pad1 = 0;
> ndm->ndm_pad2 = 0;
> - ndm->ndm_flags = 0;
> + ndm->ndm_flags = fdb->added_by_external_learn ? NTF_EXT_LEARNED : 0;
> ndm->ndm_type = 0;
> ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
> ndm->ndm_state = fdb_to_nud(fdb);
> @@ -983,3 +984,91 @@ void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p)
> }
> }
> }
> +
> +int br_fdb_external_learn_add(struct net_device *dev,
> + const unsigned char *addr, u16 vid)
> +{
> + struct net_bridge_port *p;
> + struct net_bridge *br;
> + struct hlist_head *head;
> + struct net_bridge_fdb_entry *fdb;
> + int err = 0;
> +
> + rtnl_lock();
> +
> + p = br_port_get_rtnl(dev);
> + if (!p) {
> + pr_info("bridge: %s not a bridge port\n", dev->name);
> + err = -EINVAL;
> + goto err_rtnl_unlock;
> + }
> +
> + br = p->br;
> +
> + spin_lock(&br->hash_lock);
(Since you asked to check locking...)

Most of the other fdb_add/delete/insert/update calls take this with
spin_lock_bh. Did you try this with lockdep enabled just to see if that
is needed here? I suspect that anytime br->hash_lock is taken it will
need to be with softirqs disabled from this point forward.

> +
> + head = &br->hash[br_mac_hash(addr, vid)];
> + fdb = fdb_find(head, addr, vid);
> + if (!fdb) {
> + fdb = fdb_create(head, p, addr, vid);
> + if (!fdb) {
> + err = -ENOMEM;
> + goto err_unlock;
> + }
> + fdb->added_by_external_learn = 1;
> + fdb_notify(br, fdb, RTM_NEWNEIGH);
> + } else if (fdb->added_by_external_learn) {
> + /* Refresh entry */
> + fdb->updated = fdb->used = jiffies;
> + } else if (!fdb->added_by_user) {
> + /* Take over SW learned entry */
> + fdb->added_by_external_learn = 1;
> + fdb->updated = jiffies;
> + fdb_notify(br, fdb, RTM_NEWNEIGH);
> + }
> +
> +err_unlock:
> + spin_unlock(&br->hash_lock);
> +err_rtnl_unlock:
> + rtnl_unlock();
> +
> + return err;
> +}
> +EXPORT_SYMBOL(br_fdb_external_learn_add);
> +
> +int br_fdb_external_learn_del(struct net_device *dev,
> + const unsigned char *addr, u16 vid)
> +{
> + struct net_bridge_port *p;
> + struct net_bridge *br;
> + struct hlist_head *head;
> + struct net_bridge_fdb_entry *fdb;
> + int err = 0;
> +
> + rtnl_lock();
> +
> + p = br_port_get_rtnl(dev);
> + if (!p) {
> + pr_info("bridge: %s not a bridge port\n", dev->name);
> + err = -EINVAL;
> + goto err_rtnl_unlock;
> + }
> +
> + br = p->br;
> +
> + spin_lock(&br->hash_lock);
Same comment as above here.

> +
> + head = &br->hash[br_mac_hash(addr, vid)];
> + fdb = fdb_find(head, addr, vid);
> + if (fdb && fdb->added_by_external_learn)
> + fdb_delete(br, fdb);
> + else
> + err = -ENOENT;
> +
> + spin_unlock(&br->hash_lock);
> +err_rtnl_unlock:
> + rtnl_unlock();
> +
> + return err;
> +}
> +EXPORT_SYMBOL(br_fdb_external_learn_del);
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 4f577c4..02cd63b 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -101,6 +101,7 @@ struct net_bridge_fdb_entry
> unsigned char is_local;
> unsigned char is_static;
> unsigned char added_by_user;
> + unsigned char added_by_external_learn;
> __u16 vlan_id;
> };
>
> --
> 1.9.3
>