[IPV4]: The scheduled removal of multipath cached routing support.

With help from Chris Wedgwood.

Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/feature-removal-schedule.txt

@@ -262,25 +262,6 @@ Who:	Richard Purdie <rpurdie@rpsys.net>
 
 ---------------------------
 
-What:	Multipath cached routing support in ipv4
-When:	in 2.6.23
-Why:	Code was merged, then submitter immediately disappeared leaving
-	us with no maintainer and lots of bugs.  The code should not have
-	been merged in the first place, and many aspects of it's
-	implementation are blocking more critical core networking
-	development.  It's marked EXPERIMENTAL and no distribution
-	enables it because it cause obscure crashes due to unfixable bugs
-	(interfaces don't return errors so memory allocation can't be
-	handled, calling contexts of these interfaces make handling
-	errors impossible too because they get called after we've
-	totally commited to creating a route object, for example).
-	This problem has existed for years and no forward progress
-	has ever been made, and nobody steps up to try and salvage
-	this code, so we're going to finally just get rid of it.
-Who:	David S. Miller <davem@davemloft.net>
-
----------------------------
-
 What:	read_dev_chars(), read_conf_data{,_lpm}() (s390 common I/O layer)
 When:	December 2007
 Why:	These functions are a leftover from 2.4 times. They have several

include/linux/Kbuild

@@ -91,7 +91,6 @@ header-y += in6.h
 header-y += in_route.h
 header-y += ioctl.h
 header-y += ipmi_msgdefs.h
-header-y += ip_mp_alg.h
 header-y += ipsec.h
 header-y += ipx.h
 header-y += irda.h

include/linux/rtnetlink.h

@@ -261,7 +261,7 @@ enum rtattr_type_t
 	RTA_FLOW,
 	RTA_CACHEINFO,
 	RTA_SESSION,
-	RTA_MP_ALGO,
+	RTA_MP_ALGO, /* no longer used */
 	RTA_TABLE,
 	__RTA_MAX
 };

include/net/dst.h

@@ -47,7 +47,6 @@ struct dst_entry
 #define DST_NOXFRM		2
 #define DST_NOPOLICY		4
 #define DST_NOHASH		8
-#define DST_BALANCED            0x10
 	unsigned long		expires;
 
 	unsigned short		header_len;	/* more space at head required */

include/net/ip_fib.h

@@ -39,7 +39,6 @@ struct fib_config {
 	int			fc_mx_len;
 	int			fc_mp_len;
 	u32			fc_flow;
-	u32			fc_mp_alg;
 	u32			fc_nlflags;
 	struct nl_info		fc_nlinfo;
  };
@@ -85,9 +84,6 @@ struct fib_info {
 	int			fib_nhs;
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 	int			fib_power;
-#endif
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-	u32			fib_mp_alg;
 #endif
 	struct fib_nh		fib_nh[0];
 #define fib_dev		fib_nh[0].nh_dev
@@ -103,10 +99,6 @@ struct fib_result {
 	unsigned char	nh_sel;
 	unsigned char	type;
 	unsigned char	scope;
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-	__be32          network;
-	__be32          netmask;
-#endif
 	struct fib_info *fi;
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_rule	*r;
@@ -145,14 +137,6 @@ struct fib_result_nl {
 #define FIB_RES_DEV(res)		(FIB_RES_NH(res).nh_dev)
 #define FIB_RES_OIF(res)		(FIB_RES_NH(res).nh_oif)
 
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-#define FIB_RES_NETWORK(res)		((res).network)
-#define FIB_RES_NETMASK(res)	        ((res).netmask)
-#else /* CONFIG_IP_ROUTE_MULTIPATH_CACHED */
-#define FIB_RES_NETWORK(res)		(0)
-#define FIB_RES_NETMASK(res)	        (0)
-#endif /* CONFIG_IP_ROUTE_MULTIPATH_WRANDOM */
-
 struct fib_table {
 	struct hlist_node tb_hlist;
 	u32		tb_id;

include/net/route.h

@@ -62,7 +62,6 @@ struct rtable
 
 	unsigned		rt_flags;
 	__u16			rt_type;
-	__u16			rt_multipath_alg;
 
 	__be32			rt_dst;	/* Path destination	*/
 	__be32			rt_src;	/* Path source		*/

net/ipv4/Kconfig

@@ -116,48 +116,6 @@ config IP_ROUTE_MULTIPATH
 	  equal "cost" and chooses one of them in a non-deterministic fashion
 	  if a matching packet arrives.
 
-config IP_ROUTE_MULTIPATH_CACHED
-	bool "IP: equal cost multipath with caching support (EXPERIMENTAL)"
-	depends on IP_ROUTE_MULTIPATH
-	help
-	  Normally, equal cost multipath routing is not supported by the
-	  routing cache. If you say Y here, alternative routes are cached
-	  and on cache lookup a route is chosen in a configurable fashion.
-
-	  If unsure, say N.
-
-config IP_ROUTE_MULTIPATH_RR
-	tristate "MULTIPATH: round robin algorithm"
-	depends on IP_ROUTE_MULTIPATH_CACHED
-	help
-	  Multipath routes are chosen according to Round Robin
-
-config IP_ROUTE_MULTIPATH_RANDOM
-	tristate "MULTIPATH: random algorithm"
-	depends on IP_ROUTE_MULTIPATH_CACHED
-	help
-	  Multipath routes are chosen in a random fashion. Actually,
-	  there is no weight for a route. The advantage of this policy
-	  is that it is implemented stateless and therefore introduces only
-	  a very small delay.
-
-config IP_ROUTE_MULTIPATH_WRANDOM
-	tristate "MULTIPATH: weighted random algorithm"
-	depends on IP_ROUTE_MULTIPATH_CACHED
-	help
-	  Multipath routes are chosen in a weighted random fashion. 
-	  The per route weights are the weights visible via ip route 2. As the
-	  corresponding state management introduces some overhead routing delay
-	  is increased.
-
-config IP_ROUTE_MULTIPATH_DRR
-	tristate "MULTIPATH: interface round robin algorithm"
-	depends on IP_ROUTE_MULTIPATH_CACHED
-	help
-	  Connections are distributed in a round robin fashion over the
-	  available interfaces. This policy makes sense if the connections 
-	  should be primarily distributed on interfaces and not on routes. 
-
 config IP_ROUTE_VERBOSE
 	bool "IP: verbose route monitoring"
 	depends on IP_ADVANCED_ROUTER

net/ipv4/Makefile

@@ -29,14 +29,9 @@ obj-$(CONFIG_INET_TUNNEL) += tunnel4.o
 obj-$(CONFIG_INET_XFRM_MODE_TRANSPORT) += xfrm4_mode_transport.o
 obj-$(CONFIG_INET_XFRM_MODE_TUNNEL) += xfrm4_mode_tunnel.o
 obj-$(CONFIG_IP_PNP) += ipconfig.o
-obj-$(CONFIG_IP_ROUTE_MULTIPATH_RR) += multipath_rr.o
-obj-$(CONFIG_IP_ROUTE_MULTIPATH_RANDOM) += multipath_random.o
-obj-$(CONFIG_IP_ROUTE_MULTIPATH_WRANDOM) += multipath_wrandom.o
-obj-$(CONFIG_IP_ROUTE_MULTIPATH_DRR) += multipath_drr.o
 obj-$(CONFIG_NETFILTER)	+= netfilter.o netfilter/
 obj-$(CONFIG_IP_VS) += ipvs/
 obj-$(CONFIG_INET_DIAG) += inet_diag.o 
-obj-$(CONFIG_IP_ROUTE_MULTIPATH_CACHED) += multipath.o
 obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o
 obj-$(CONFIG_NET_TCPPROBE) += tcp_probe.o
 obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o

net/ipv4/fib_frontend.c

@@ -453,7 +453,6 @@ const struct nla_policy rtm_ipv4_policy[RTA_MAX+1] = {
 	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },
 	[RTA_PROTOINFO]		= { .type = NLA_U32 },
 	[RTA_FLOW]		= { .type = NLA_U32 },
-	[RTA_MP_ALGO]		= { .type = NLA_U32 },
 };
 
 static int rtm_to_fib_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -515,9 +514,6 @@ static int rtm_to_fib_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 		case RTA_FLOW:
 			cfg->fc_flow = nla_get_u32(attr);
 			break;
-		case RTA_MP_ALGO:
-			cfg->fc_mp_alg = nla_get_u32(attr);
-			break;
 		case RTA_TABLE:
 			cfg->fc_table = nla_get_u32(attr);
 			break;

net/ipv4/fib_semantics.c

@@ -42,7 +42,6 @@
 #include <net/tcp.h>
 #include <net/sock.h>
 #include <net/ip_fib.h>
-#include <net/ip_mp_alg.h>
 #include <net/netlink.h>
 #include <net/nexthop.h>
 
@@ -697,13 +696,6 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 			goto err_inval;
 	}
 #endif
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-	if (cfg->fc_mp_alg) {
-		if (cfg->fc_mp_alg < IP_MP_ALG_NONE ||
-		    cfg->fc_mp_alg > IP_MP_ALG_MAX)
-			goto err_inval;
-	}
-#endif
 
 	err = -ENOBUFS;
 	if (fib_info_cnt >= fib_hash_size) {
@@ -791,10 +783,6 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 #endif
 	}
 
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-	fi->fib_mp_alg = cfg->fc_mp_alg;
-#endif
-
 	if (fib_props[cfg->fc_type].error) {
 		if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 			goto err_inval;
@@ -940,10 +928,6 @@ int fib_semantic_match(struct list_head *head, const struct flowi *flp,
 	res->type = fa->fa_type;
 	res->scope = fa->fa_scope;
 	res->fi = fa->fa_info;
-#ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
-	res->netmask = mask;
-	res->network = zone & inet_make_mask(prefixlen);
-#endif
 	atomic_inc(&res->fi->fib_clntref);
 	return 0;
 }