Revert "ipv6: Factorise ip6_route_multipath_add()."

Commit 71c0efb6d12f ("ipv6: Factorise ip6_route_multipath_add().") split
a loop in ip6_route_multipath_add() so that we can put rcu_read_lock()
between ip6_route_info_create() and ip6_route_info_create_nh().

We no longer need to do so as ip6_route_info_create_nh() does not require
RCU now.

Let's revert the commit to simplify the code.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a87091dd06b1ba7e3c9b1730f05d101b770fd238..96ae21da9961db7279d9acf43ad5daecd911d1de 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5335,131 +5335,29 @@ struct rt6_nh {
        struct fib6_info *fib6_info;
        struct fib6_config r_cfg;
        struct list_head list;
-       int weight;
 };
 
-static void ip6_route_mpath_info_cleanup(struct list_head *rt6_nh_list)
+static int ip6_route_info_append(struct list_head *rt6_nh_list,
+                                struct fib6_info *rt,
+                                struct fib6_config *r_cfg)
 {
-       struct rt6_nh *nh, *nh_next;
+       struct rt6_nh *nh;
 
-       list_for_each_entry_safe(nh, nh_next, rt6_nh_list, list) {
-               struct fib6_info *rt = nh->fib6_info;
-
-               if (rt) {
-                       free_percpu(rt->fib6_nh->nh_common.nhc_pcpu_rth_output);
-                       free_percpu(rt->fib6_nh->rt6i_pcpu);
-                       ip_fib_metrics_put(rt->fib6_metrics);
-                       kfree(rt);
-               }
-
-               list_del(&nh->list);
-               kfree(nh);
+       list_for_each_entry(nh, rt6_nh_list, list) {
+               /* check if fib6_info already exists */
+               if (rt6_duplicate_nexthop(nh->fib6_info, rt))
+                       return -EEXIST;
        }
-}
-
-static int ip6_route_mpath_info_create(struct list_head *rt6_nh_list,
-                                      struct fib6_config *cfg,
-                                      struct netlink_ext_ack *extack)
-{
-       struct rtnexthop *rtnh;
-       int remaining;
-       int err;
-
-       remaining = cfg->fc_mp_len;
-       rtnh = (struct rtnexthop *)cfg->fc_mp;
-
-       /* Parse a Multipath Entry and build a list (rt6_nh_list) of
-        * fib6_info structs per nexthop
-        */
-       while (rtnh_ok(rtnh, remaining)) {
-               struct fib6_config r_cfg;
-               struct fib6_info *rt;
-               struct rt6_nh *nh;
-               int attrlen;
-
-               nh = kzalloc(sizeof(*nh), GFP_KERNEL);
-               if (!nh) {
-                       err = -ENOMEM;
-                       goto err;
-               }
 
-               list_add_tail(&nh->list, rt6_nh_list);
-
-               memcpy(&r_cfg, cfg, sizeof(*cfg));
-               if (rtnh->rtnh_ifindex)
-                       r_cfg.fc_ifindex = rtnh->rtnh_ifindex;
-
-               attrlen = rtnh_attrlen(rtnh);
-               if (attrlen > 0) {
-                       struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
-
-                       nla = nla_find(attrs, attrlen, RTA_GATEWAY);
-                       if (nla) {
-                               r_cfg.fc_gateway = nla_get_in6_addr(nla);
-                               r_cfg.fc_flags |= RTF_GATEWAY;
-                       }
-
-                       r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
-                       nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
-                       if (nla)
-                               r_cfg.fc_encap_type = nla_get_u16(nla);
-               }
-
-               r_cfg.fc_flags |= (rtnh->rtnh_flags & RTNH_F_ONLINK);
-
-               rt = ip6_route_info_create(&r_cfg, GFP_KERNEL, extack);
-               if (IS_ERR(rt)) {
-                       err = PTR_ERR(rt);
-                       goto err;
-               }
-
-               nh->fib6_info = rt;
-               nh->weight = rtnh->rtnh_hops + 1;
-               memcpy(&nh->r_cfg, &r_cfg, sizeof(r_cfg));
+       nh = kzalloc(sizeof(*nh), GFP_KERNEL);
+       if (!nh)
+               return -ENOMEM;
 
-               rtnh = rtnh_next(rtnh, &remaining);
-       }
+       nh->fib6_info = rt;
+       memcpy(&nh->r_cfg, r_cfg, sizeof(*r_cfg));
+       list_add_tail(&nh->list, rt6_nh_list);
 
        return 0;
-err:
-       ip6_route_mpath_info_cleanup(rt6_nh_list);
-       return err;
-}
-
-static int ip6_route_mpath_info_create_nh(struct list_head *rt6_nh_list,
-                                         struct netlink_ext_ack *extack)
-{
-       struct rt6_nh *nh, *nh_next, *nh_tmp;
-       LIST_HEAD(tmp);
-       int err;
-
-       list_for_each_entry_safe(nh, nh_next, rt6_nh_list, list) {
-               struct fib6_info *rt = nh->fib6_info;
-
-               err = ip6_route_info_create_nh(rt, &nh->r_cfg, extack);
-               if (err) {
-                       nh->fib6_info = NULL;
-                       goto err;
-               }
-
-               rt->fib6_nh->fib_nh_weight = nh->weight;
-
-               list_move_tail(&nh->list, &tmp);
-
-               list_for_each_entry(nh_tmp, rt6_nh_list, list) {
-                       /* check if fib6_info already exists */
-                       if (rt6_duplicate_nexthop(nh_tmp->fib6_info, rt)) {
-                               err = -EEXIST;
-                               goto err;
-                       }
-               }
-       }
-out:
-       list_splice(&tmp, rt6_nh_list);
-       return err;
-err:
-       ip6_route_mpath_info_cleanup(rt6_nh_list);
-       goto out;
 }
 
 static void ip6_route_mpath_notify(struct fib6_info *rt,
@@ -5519,11 +5417,16 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
        struct fib6_info *rt_notif = NULL, *rt_last = NULL;
        struct nl_info *info = &cfg->fc_nlinfo;
        struct rt6_nh *nh, *nh_safe;
+       struct fib6_config r_cfg;
+       struct rtnexthop *rtnh;
        LIST_HEAD(rt6_nh_list);
        struct rt6_nh *err_nh;
+       struct fib6_info *rt;
        __u16 nlflags;
-       int nhn = 0;
+       int remaining;
+       int attrlen;
        int replace;
+       int nhn = 0;
        int err;
 
        replace = (cfg->fc_nlinfo.nlh &&
@@ -5533,13 +5436,57 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
        if (info->nlh && info->nlh->nlmsg_flags & NLM_F_APPEND)
                nlflags |= NLM_F_APPEND;
 
-       err = ip6_route_mpath_info_create(&rt6_nh_list, cfg, extack);
-       if (err)
-               return err;
+       remaining = cfg->fc_mp_len;
+       rtnh = (struct rtnexthop *)cfg->fc_mp;
 
-       err = ip6_route_mpath_info_create_nh(&rt6_nh_list, extack);
-       if (err)
-               goto cleanup;
+       /* Parse a Multipath Entry and build a list (rt6_nh_list) of
+        * fib6_info structs per nexthop
+        */
+       while (rtnh_ok(rtnh, remaining)) {
+               memcpy(&r_cfg, cfg, sizeof(*cfg));
+               if (rtnh->rtnh_ifindex)
+                       r_cfg.fc_ifindex = rtnh->rtnh_ifindex;
+
+               attrlen = rtnh_attrlen(rtnh);
+               if (attrlen > 0) {
+                       struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
+
+                       nla = nla_find(attrs, attrlen, RTA_GATEWAY);
+                       if (nla) {
+                               r_cfg.fc_gateway = nla_get_in6_addr(nla);
+                               r_cfg.fc_flags |= RTF_GATEWAY;
+                       }
+
+                       r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
+                       nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
+                       if (nla)
+                               r_cfg.fc_encap_type = nla_get_u16(nla);
+               }
+
+               r_cfg.fc_flags |= (rtnh->rtnh_flags & RTNH_F_ONLINK);
+               rt = ip6_route_info_create(&r_cfg, GFP_KERNEL, extack);
+               if (IS_ERR(rt)) {
+                       err = PTR_ERR(rt);
+                       rt = NULL;
+                       goto cleanup;
+               }
+
+               err = ip6_route_info_create_nh(rt, &r_cfg, extack);
+               if (err) {
+                       rt = NULL;
+                       goto cleanup;
+               }
+
+               rt->fib6_nh->fib_nh_weight = rtnh->rtnh_hops + 1;
+
+               err = ip6_route_info_append(&rt6_nh_list, rt, &r_cfg);
+               if (err) {
+                       fib6_info_release(rt);
+                       goto cleanup;
+               }
+
+               rtnh = rtnh_next(rtnh, &remaining);
+       }
 
        /* for add and replace send one notification with all nexthops.
         * Skip the notification in fib6_add_rt2node and send one with