[NETLINK]: Do precise netlink message allocations where possible

[powerpc.git] / net / ipv4 / fib_semantics.c

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 884d176..e63b8a9 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -273,25 +273,49 @@ int ip_fib_check_default(__be32 gw, struct net_device *dev)
        return -1;
 }
 
+static inline size_t fib_nlmsg_size(struct fib_info *fi)
+{
+       size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
+                        + nla_total_size(4) /* RTA_TABLE */
+                        + nla_total_size(4) /* RTA_DST */
+                        + nla_total_size(4) /* RTA_PRIORITY */
+                        + nla_total_size(4); /* RTA_PREFSRC */
+
+       /* space for nested metrics */
+       payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
+
+       if (fi->fib_nhs) {
+               /* Also handles the special case fib_nhs == 1 */
+
+               /* each nexthop is packed in an attribute */
+               size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
+
+               /* may contain flow and gateway attribute */
+               nhsize += 2 * nla_total_size(4);
+
+               /* all nexthops are packed in a nested attribute */
+               payload += nla_total_size(fi->fib_nhs * nhsize);
+       }
+
+       return payload;
+}
+
 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
               int dst_len, u32 tb_id, struct nl_info *info)
 {
        struct sk_buff *skb;
-       int payload = sizeof(struct rtmsg) + 256;
        u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
        int err = -ENOBUFS;
 
-       skb = nlmsg_new(nlmsg_total_size(payload), GFP_KERNEL);
+       skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
        if (skb == NULL)
                goto errout;
 
        err = fib_dump_info(skb, info->pid, seq, event, tb_id,
                            fa->fa_type, fa->fa_scope, key, dst_len,
                            fa->fa_tos, fa->fa_info, 0);
-       if (err < 0) {
-               kfree_skb(skb);
-               goto errout;
-       }
+       /* failure implies BUG in fib_nlmsg_size() */
+       BUG_ON(err < 0);
 
        err = rtnl_notify(skb, info->pid, RTNLGRP_IPV4_ROUTE,
                          info->nlh, GFP_KERNEL);