Re: [PATCH net-next 1/3] net: add IPv4 routing FIB support for swdev

[Scott Feldman <sfeldma@gmail.com>]

On Fri, Jan 2, 2015 at 3:39 AM, Arad, Ronen <ronen.arad@intel.com> wrote:
>
>
>>-----Original Message-----
>>From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org] On
>>Behalf Of Scott Feldman
>>Sent: Friday, January 02, 2015 10:01 AM
>>To: roopa
>>Cc: Netdev; Jiří Pírko; john fastabend; Thomas Graf; Jamal Hadi Salim; Andy
>>Gospodarek
>>Subject: Re: [PATCH net-next 1/3] net: add IPv4 routing FIB support for swdev
>>
>>On Thu, Jan 1, 2015 at 9:49 PM, roopa <roopa@cumulusnetworks.com> wrote:
>>> On 1/1/15, 7:29 PM, sfeldma@gmail.com wrote:
>>>>
>>>> From: Scott Feldman <sfeldma@gmail.com>
>>>>
>>>> To offload IPv4 L3 routing functions to swdev device, the swdev device
>>>> driver
>>>> implements two new ndo ops (ndo_switch_fib_ipv4_add/del).  The ops are
>>>> called
>>>> by the core IPv4 FIB code when installing/removing FIB entries to/from the
>>>> kernel FIB.  On install, the driver should return 0 if FIB entry (route)
>>>> can be
>>>> installed to device for offloading, -EOPNOTSUPP if route cannot be
>>>> installed
>>>> due to device limitations, and other negative error code on failure to
>>>> install
>>>> route to device.  On failure error code, the route is not installed to
>>>> device,
>>>> and not installed in kernel FIB, and the return code is propagated back to
>>>> the
>>>> user-space caller (via netlink).  An -EOPNOTSUPP error code is skipped for
>>>> the
>>>> device but installed in the kernel FIB.
>>>>
>>>> The FIB entry (route) nexthop list is used to find the swdev device port
>>>> to
>>>> anchor the ndo op call.  The route's fib_dev (the first nexthop's dev) is
>>>> used
>>>> find the swdev port by recursively traversing the fib_dev's lower_dev list
>>>> until a swdev port is found.  The ndo op is called on this swdev port.
>>>
>>>
>>> scott, I posted a similar api for bridge attribute sets. But, nobody
>>> supported it.
>>> http://marc.info/?l=linux-netdev&m=141820234410602&w=2
>>>
>>> If this is acceptable, I will be resubmitting my api as well.
>>>
>>
>>This may get shot down as well, who knows?
>>
>>For routes, the nexthop dev may be a bridge or a bond for an IP on the
>>router, so we have no choice but to walk down from the bridge or the
>>bond to find a swport dev to call the ndo op to install the route.
>>
> Another case is when VLAN-aware bridge with VLAN filtering is used. In that
> case IP interfaces are VLAN interfaces created on top of the bridge.
>
>>For bridge settings, I remember someone raised the issue that settings
>>should be propagated down the dev hierarchy, with parent calling
>>child's op and so on.  I'll go back and look at your post.
>>
> This was my comment. I'm not sure it was correct. My concern was the VLAN
> interface on top of a VLAN-aware bridge use-case. I now believe that such
> interfaces are upper devices of the bridge (not master). Therefore, it seems
> that traversal starting at a VLAN interface on top of a bridge will follow a
> path: VLAN interface => bridge => [team/bond] => switchdev port.

With the VLAN support built into the bridge, we can avoid the vlan
interface, which makes it a little better:

bridge/vlan => [team/bond] => swdev port

> One complication here is that the VLAN context is important. A "naked" nexthop
> shall only be resolved within the VLAN associated with the VLAN interface. When
> ARP resolution is performed by Linux stack, it goes via the VLAN interface
> which imposes a tag on the packet before handing it to the bridge. The VLAN-
> aware bridge floods such packet only to member ports of the VLAN. This behavior
> of the software bridge has to be preserved with offloaded L3 forwarding and
> offloaded L2 switching.

Good point, and valid for bridge/vlans as well.


>>>
>>>
>>>>
>>>> Since the FIB entry is "naked" when push from the kernel, the
>>>> driver/device
>>>> is responsible for resolving the route's nexthops to neighbor MAC
>>>> addresses.
>>>> This can be done by the driver by monitoring NETEVENT_NEIGH_UPDATE
>>>> netevent notifier to watch for ARP activity.  Once a nexthop is resolved
>>>> to
>>>> neighbor MAC address, it can be installed to the device and the device
>>>> will
>>>> do the L3 routing offload in HW, for that nexthop.
>>>>
>>>> Signed-off-by: Scott Feldman <sfeldma@gmail.com>
>>>> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
>>>> ---
>>>>   include/linux/netdevice.h |   22 +++++++++++
>>>>   include/net/switchdev.h   |   18 +++++++++
>>>>   net/ipv4/fib_trie.c       |   17 ++++++++-
>>>>   net/switchdev/switchdev.c |   89
>>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>>   4 files changed, 145 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>>> index 679e6e9..b66d22b 100644
>>>> --- a/include/linux/netdevice.h
>>>> +++ b/include/linux/netdevice.h
>>>> @@ -767,6 +767,8 @@ struct netdev_phys_item_id {
>>>>   typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
>>>>                                        struct sk_buff *skb);
>>>>   +struct fib_info;
>>>> +
>>>>   /*
>>>>    * This structure defines the management hooks for network devices.
>>>>    * The following hooks can be defined; unless noted otherwise, they are
>>>> @@ -1030,6 +1032,14 @@ typedef u16 (*select_queue_fallback_t)(struct
>>>> net_device *dev,
>>>>    * int (*ndo_switch_port_stp_update)(struct net_device *dev, u8 state);
>>>>    *    Called to notify switch device port of bridge port STP
>>>>    *    state change.
>>>> + * int (*ndo_sw_parent_fib_ipv4_add)(struct net_device *dev, __be32 dst,
>>>> + *                                  int dst_len, struct fib_info *fi,
>>>> + *                                  u8 tos, u8 type, u32 tb_id);
>>>> + *     Called to add IPv4 route to switch device.
>>>> + * int (*ndo_sw_parent_fib_ipv4_del)(struct net_device *dev, __be32 dst,
>>>> + *                                  int dst_len, struct fib_info *fi,
>>>> + *                                  u8 tos, u8 type, u32 tb_id);
>>>> + *     Called to delete IPv4 route from switch device.
>>>>    */
>>>>   struct net_device_ops {
>>>>         int                     (*ndo_init)(struct net_device *dev);
>>>> @@ -1189,6 +1199,18 @@ struct net_device_ops {
>>>>                                                             struct
>>>> netdev_phys_item_id *psid);
>>>>         int                     (*ndo_switch_port_stp_update)(struct
>>>> net_device *dev,
>>>>                                                               u8 state);
>>>> +       int                     (*ndo_switch_fib_ipv4_add)(struct
>>>> net_device *dev,
>>>> +                                                          __be32 dst,
>>>> +                                                          int dst_len,
>>>> +                                                          struct fib_info
>>>> *fi,
>>>> +                                                          u8 tos, u8
>>>> type,
>>>> +                                                          u32 tb_id);
>>>> +       int                     (*ndo_switch_fib_ipv4_del)(struct
>>>> net_device *dev,
>>>> +                                                          __be32 dst,
>>>> +                                                          int dst_len,
>>>> +                                                          struct fib_info
>>>> *fi,
>>>> +                                                          u8 tos, u8
>>>> type,
>>>> +                                                          u32 tb_id);
>>>>   #endif
>>>>   };
>>>>   diff --git a/include/net/switchdev.h b/include/net/switchdev.h
>>>> index 8a6d164..caebc2a 100644
>>>> --- a/include/net/switchdev.h
>>>> +++ b/include/net/switchdev.h
>>>> @@ -17,6 +17,10 @@
>>>>   int netdev_switch_parent_id_get(struct net_device *dev,
>>>>                                 struct netdev_phys_item_id *psid);
>>>>   int netdev_switch_port_stp_update(struct net_device *dev, u8 state);
>>>> +int netdev_switch_fib_ipv4_add(u32 dst, int dst_len, struct fib_info *fi,
>>>> +                              u8 tos, u8 type, u32 tb_id);
>>>> +int netdev_switch_fib_ipv4_del(u32 dst, int dst_len, struct fib_info *fi,
>>>> +                              u8 tos, u8 type, u32 tb_id);
>>>>     #else
>>>>   @@ -32,6 +36,20 @@ static inline int
>>>> netdev_switch_port_stp_update(struct net_device *dev,
>>>>         return -EOPNOTSUPP;
>>>>   }
>>>>   +static inline int netdev_switch_fib_ipv4_add(u32 dst, int dst_len,
>>>> +                                            struct fib_info *fi,
>>>> +                                            u8 tos, u8 type, u32 tb_id)
>>>> +{
>>>> +       return -EOPNOTSUPP;
>>>> +}
>>>> +
>>>> +static inline int netdev_switch_fib_ipv4_del(u32 dst, int dst_len,
>>>> +                                            struct fib_info *fi,
>>>> +                                            u8 tos, u8 type, u32 tb_id)
>>>> +{
>>>> +       return -EOPNOTSUPP;
>>>> +}
>>>> +
>>>>   #endif
>>>>     #endif /* _LINUX_SWITCHDEV_H_ */
>>>> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
>>>> index 281e5e0..ea2dc17 100644
>>>> --- a/net/ipv4/fib_trie.c
>>>> +++ b/net/ipv4/fib_trie.c
>>>> @@ -79,6 +79,7 @@
>>>>   #include <net/tcp.h>
>>>>   #include <net/sock.h>
>>>>   #include <net/ip_fib.h>
>>>> +#include <net/switchdev.h>
>>>>   #include "fib_lookup.h"
>>>>     #define MAX_STAT_DEPTH 32
>>>> @@ -1201,6 +1202,8 @@ int fib_table_insert(struct fib_table *tb, struct
>>>> fib_config *cfg)
>>>>                         fib_release_info(fi_drop);
>>>>                         if (state & FA_S_ACCESSED)
>>>>                                 rt_cache_flush(cfg->fc_nlinfo.nl_net);
>>>> +                       netdev_switch_fib_ipv4_add(key, plen, fi,
>>>> fa->fa_tos,
>>>> +                                                  cfg->fc_type,
>>>> tb->tb_id);
>>>>                         rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
>>>>                                 tb->tb_id, &cfg->fc_nlinfo,
>>>> NLM_F_REPLACE);
>>>>   @@ -1229,6 +1232,13 @@ int fib_table_insert(struct fib_table *tb, struct
>>>> fib_config *cfg)
>>>>         new_fa->fa_tos = tos;
>>>>         new_fa->fa_type = cfg->fc_type;
>>>>         new_fa->fa_state = 0;
>>>> +
>>>> +       /* (Optionally) offload fib info to switch hardware. */
>>>> +       err = netdev_switch_fib_ipv4_add(key, plen, fi, tos,
>>>> +                                        cfg->fc_type, tb->tb_id);
>>>> +       if (err && err != -EOPNOTSUPP)
>>>> +               goto out_free_new_fa;
>>>> +
>>>>         /*
>>>>          * Insert new entry to the list.
>>>>          */
>>>> @@ -1237,7 +1247,7 @@ int fib_table_insert(struct fib_table *tb, struct
>>>> fib_config *cfg)
>>>>                 fa_head = fib_insert_node(t, key, plen);
>>>>                 if (unlikely(!fa_head)) {
>>>>                         err = -ENOMEM;
>>>> -                       goto out_free_new_fa;
>>>> +                       goto out_sw_fib_del;
>>>>                 }
>>>>         }
>>>>   @@ -1253,6 +1263,8 @@ int fib_table_insert(struct fib_table *tb, struct
>>>> fib_config *cfg)
>>>>   succeeded:
>>>>         return 0;
>>>>   +out_sw_fib_del:
>>>> +       netdev_switch_fib_ipv4_del(key, plen, fi, tos, cfg->fc_type,
>>>> tb->tb_id);
>>>>   out_free_new_fa:
>>>>         kmem_cache_free(fn_alias_kmem, new_fa);
>>>>   out:
>>>> @@ -1529,6 +1541,9 @@ int fib_table_delete(struct fib_table *tb, struct
>>>> fib_config *cfg)
>>>>         rtmsg_fib(RTM_DELROUTE, htonl(key), fa, plen, tb->tb_id,
>>>>                   &cfg->fc_nlinfo, 0);
>>>>   +     netdev_switch_fib_ipv4_del(key, plen, fa->fa_info, tos,
>>>> +                                  cfg->fc_type, tb->tb_id);
>>>> +
>>>>         list_del_rcu(&fa->fa_list);
>>>>         if (!plen)
>>>> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
>>>> index d162b21..211a8a0 100644
>>>> --- a/net/switchdev/switchdev.c
>>>> +++ b/net/switchdev/switchdev.c
>>>> @@ -12,6 +12,7 @@
>>>>   #include <linux/types.h>
>>>>   #include <linux/init.h>
>>>>   #include <linux/netdevice.h>
>>>> +#include <net/ip_fib.h>
>>>>   #include <net/switchdev.h>
>>>>     /**
>>>> @@ -50,3 +51,91 @@ int netdev_switch_port_stp_update(struct net_device
>>>> *dev, u8 state)
>>>>         return ops->ndo_switch_port_stp_update(dev, state);
>>>>   }
>>>>   EXPORT_SYMBOL(netdev_switch_port_stp_update);
>>>> +
>>>> +static struct net_device *netdev_switch_get_by_fib_dev(struct net_device
>>>> *dev)
>>>> +{
>>>> +       const struct net_device_ops *ops = dev->netdev_ops;
>>>> +       struct net_device *lower_dev;
>>>> +       struct net_device *port_dev;
>>>> +       struct list_head *iter;
>>>> +
>>>> +       /* Recusively search from fib_dev down until we find
>>>> +        * a sw port dev.  (A sw port dev supports
>>>> +        * ndo_switch_parent_id_get).
>>>> +        */
>>>> +
>>>> +       if (ops->ndo_switch_parent_id_get)
>>>> +               return dev;
>>>> +
>>>> +       netdev_for_each_lower_dev(dev, lower_dev, iter) {
>>>> +               port_dev = netdev_switch_get_by_fib_dev(lower_dev);
>>>> +               if (port_dev)
>>>> +                       return port_dev;
>>>> +       }
>>>> +
>>>> +       return NULL;
>>>> +}
>>>> +
>>>> +/**
>>>> + *     netdev_switch_fib_ipv4_add - Add IPv4 route entry to switch
>>>> + *
>>>> + *     @dst: route's IPv4 destination address
>>>> + *     @dst_len: destination address length (prefix length)
>>>> + *     @fi: route FIB info structure
>>>> + *     @tos: route TOS
>>>> + *     @type: route type
>>>> + *     @tb_id: route table ID
>>>> + *
>>>> + *     Add IPv4 route entry to switch device.
>>>> + */
>>>> +int netdev_switch_fib_ipv4_add(u32 dst, int dst_len, struct fib_info *fi,
>>>> +                              u8 tos, u8 type, u32 tb_id)
>>>> +{
>>>> +       struct net_device *dev;
>>>> +       const struct net_device_ops *ops;
>>>> +       int err = -EOPNOTSUPP;
>>>> +
>>>> +       dev = netdev_switch_get_by_fib_dev(fi->fib_dev);
>>>> +       if (!dev)
>>>> +               return -EOPNOTSUPP;
>>>> +       ops = dev->netdev_ops;
>>>> +
>>>> +       if (ops->ndo_switch_fib_ipv4_add)
>>>> +               err = ops->ndo_switch_fib_ipv4_add(dev, htonl(dst),
>>>> dst_len,
>>>> +                                                  fi, tos, type, tb_id);
>>>> +
>>>> +       return err;
>>>> +}
>>>> +EXPORT_SYMBOL(netdev_switch_fib_ipv4_add);
>>>> +
>>>> +/**
>>>> + *     netdev_switch_fib_ipv4_del - Delete IPv4 route entry from switch
>>>> + *
>>>> + *     @dst: route's IPv4 destination address
>>>> + *     @dst_len: destination address length (prefix length)
>>>> + *     @fi: route FIB info structure
>>>> + *     @tos: route TOS
>>>> + *     @type: route type
>>>> + *     @tb_id: route table ID
>>>> + *
>>>> + *     Delete IPv4 route entry from switch device.
>>>> + */
>>>> +int netdev_switch_fib_ipv4_del(u32 dst, int dst_len, struct fib_info *fi,
>>>> +                              u8 tos, u8 type, u32 tb_id)
>>>> +{
>>>> +       struct net_device *dev;
>>>> +       const struct net_device_ops *ops;
>>>> +       int err = -EOPNOTSUPP;
>>>> +
>>>> +       dev = netdev_switch_get_by_fib_dev(fi->fib_dev);
>>>> +       if (!dev)
>>>> +               return -EOPNOTSUPP;
>>>> +       ops = dev->netdev_ops;
>>>> +
>>>> +       if (ops->ndo_switch_fib_ipv4_del)
>>>> +               err = ops->ndo_switch_fib_ipv4_del(dev, htonl(dst),
>>>> dst_len,
>>>> +                                                  fi, tos, type, tb_id);
>>>> +
>>>> +       return err;
>>>> +}
>>>> +EXPORT_SYMBOL(netdev_switch_fib_ipv4_del);
>>>
>>>
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