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

[roopa <roopa@cumulusnetworks.com>]

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.



>
> 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);