neighbour: Allocate skb in neigh_get().

We will remove RTNL for neigh_get() and run it under RCU instead.

neigh_get_reply() and pneigh_get_reply() allocate skb with GFP_KERNEL.

Let's move the allocation before __dev_get_by_index() in neigh_get().

Now, neigh_get_reply() and pneigh_get_reply() are inlined and
rtnl_unicast() is factorised.

We will convert pneigh_lookup() to __pneigh_lookup() later.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250716221221.442239-4-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 7b63f47cd61a3d847567c615f1a272d3758f03ef..761593ea8c919f11ccdeac7a56eff35df096bfea 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2988,27 +2988,6 @@ static inline size_t neigh_nlmsg_size(void)
               + nla_total_size(1); /* NDA_PROTOCOL */
 }
 
-static int neigh_get_reply(struct net *net, struct neighbour *neigh,
-                          u32 pid, u32 seq)
-{
-       struct sk_buff *skb;
-       int err = 0;
-
-       skb = nlmsg_new(neigh_nlmsg_size(), GFP_KERNEL);
-       if (!skb)
-               return -ENOBUFS;
-
-       err = neigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0);
-       if (err) {
-               kfree_skb(skb);
-               goto errout;
-       }
-
-       err = rtnl_unicast(skb, net, pid);
-errout:
-       return err;
-}
-
 static inline size_t pneigh_nlmsg_size(void)
 {
        return NLMSG_ALIGN(sizeof(struct ndmsg))
@@ -3017,34 +2996,16 @@ static inline size_t pneigh_nlmsg_size(void)
               + nla_total_size(1); /* NDA_PROTOCOL */
 }
 
-static int pneigh_get_reply(struct net *net, struct pneigh_entry *neigh,
-                           u32 pid, u32 seq, struct neigh_table *tbl)
-{
-       struct sk_buff *skb;
-       int err = 0;
-
-       skb = nlmsg_new(pneigh_nlmsg_size(), GFP_KERNEL);
-       if (!skb)
-               return -ENOBUFS;
-
-       err = pneigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0, tbl);
-       if (err) {
-               kfree_skb(skb);
-               goto errout;
-       }
-
-       err = rtnl_unicast(skb, net, pid);
-errout:
-       return err;
-}
-
 static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                     struct netlink_ext_ack *extack)
 {
        struct net *net = sock_net(in_skb->sk);
+       u32 pid = NETLINK_CB(in_skb).portid;
        struct net_device *dev = NULL;
        struct neigh_table *tbl = NULL;
+       u32 seq = nlh->nlmsg_seq;
        struct neighbour *neigh;
+       struct sk_buff *skb;
        struct ndmsg *ndm;
        void *dst = NULL;
        int err;
@@ -3053,11 +3014,19 @@ static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        if (IS_ERR(ndm))
                return PTR_ERR(ndm);
 
+       if (ndm->ndm_flags & NTF_PROXY)
+               skb = nlmsg_new(neigh_nlmsg_size(), GFP_KERNEL);
+       else
+               skb = nlmsg_new(pneigh_nlmsg_size(), GFP_KERNEL);
+       if (!skb)
+               return -ENOBUFS;
+
        if (ndm->ndm_ifindex) {
                dev = __dev_get_by_index(net, ndm->ndm_ifindex);
                if (!dev) {
                        NL_SET_ERR_MSG(extack, "Unknown device ifindex");
-                       return -ENODEV;
+                       err = -ENODEV;
+                       goto err_free_skb;
                }
        }
 
@@ -3067,23 +3036,30 @@ static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                pn = pneigh_lookup(tbl, net, dst, dev, 0);
                if (!pn) {
                        NL_SET_ERR_MSG(extack, "Proxy neighbour entry not found");
-                       return -ENOENT;
+                       err = -ENOENT;
+                       goto err_free_skb;
                }
-               return pneigh_get_reply(net, pn, NETLINK_CB(in_skb).portid,
-                                       nlh->nlmsg_seq, tbl);
-       }
-
-       neigh = neigh_lookup(tbl, dst, dev);
-       if (!neigh) {
-               NL_SET_ERR_MSG(extack, "Neighbour entry not found");
-               return -ENOENT;
-       }
 
-       err = neigh_get_reply(net, neigh, NETLINK_CB(in_skb).portid,
-                             nlh->nlmsg_seq);
+               err = pneigh_fill_info(skb, pn, pid, seq, RTM_NEWNEIGH, 0, tbl);
+               if (err)
+                       goto err_free_skb;
+       } else {
+               neigh = neigh_lookup(tbl, dst, dev);
+               if (!neigh) {
+                       NL_SET_ERR_MSG(extack, "Neighbour entry not found");
+                       err = -ENOENT;
+                       goto err_free_skb;
+               }
 
-       neigh_release(neigh);
+               err = neigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0);
+               neigh_release(neigh);
+               if (err)
+                       goto err_free_skb;
+       }
 
+       return rtnl_unicast(skb, net, pid);
+err_free_skb:
+       kfree_skb(skb);
        return err;
 }