ipv4: Use const'ify fib_result deep in the route call chains.

The only troublesome bit here is __mkroute_output which wants
to override res->fi and res->type, compute those in local
variables instead.

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

1 files changed, 17 insertions, 15 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 9841543c468d..2facde0985f9 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1787,10 +1787,10 @@ static void rt_init_metrics(struct rtable *rt, struct fib_info *fi)
         }
 }
 
-static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
+static void rt_set_nexthop(struct rtable *rt, const struct fib_result *res,
+                           struct fib_info *fi, u16 type, u32 itag)
 {
         struct dst_entry *dst = &rt->dst;
-        struct fib_info *fi = res->fi;
 
         if (fi) {
                 if (FIB_RES_GW(*res) &&
@@ -1813,7 +1813,7 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
 #endif
         set_class_tag(rt, itag);
 #endif
-        rt->rt_type = res->type;
+        rt->rt_type = type;
 }
 
 static struct rtable *rt_dst_alloc(bool nopolicy, bool noxfrm)
@@ -1939,7 +1939,7 @@ static void ip_handle_martian_source(struct net_device *dev,
 
 /* called in rcu_read_lock() section */
 static int __mkroute_input(struct sk_buff *skb,
-                           struct fib_result *res,
+                           const struct fib_result *res,
                            struct in_device *in_dev,
                            __be32 daddr, __be32 saddr, u32 tos,
                            struct rtable **result)
@@ -2018,7 +2018,7 @@ static int __mkroute_input(struct sk_buff *skb,
         rth->dst.output = ip_output;
         rth->rt_genid = rt_genid(dev_net(rth->dst.dev));
 
-        rt_set_nexthop(rth, res, itag);
+        rt_set_nexthop(rth, res, res->fi, res->type, itag);
 
         rth->rt_flags = flags;
 
@@ -2319,23 +2319,25 @@ skip_cache:
 EXPORT_SYMBOL(ip_route_input_common);
 
 /* called with rcu_read_lock() */
-static struct rtable *__mkroute_output(struct fib_result *res,
+static struct rtable *__mkroute_output(const struct fib_result *res,
                                        const struct flowi *fl,
                                        const struct flowi *oldflp,
                                        struct net_device *dev_out,
                                        unsigned int flags)
 {
+        struct fib_info *fi = res->fi;
         u32 tos = RT_FL_TOS(oldflp);
         struct in_device *in_dev;
+        u16 type = res->type;
         struct rtable *rth;
 
         if (ipv4_is_loopback(fl->fl4_src) && !(dev_out->flags & IFF_LOOPBACK))
                 return ERR_PTR(-EINVAL);
 
         if (ipv4_is_lbcast(fl->fl4_dst))
-                res->type = RTN_BROADCAST;
+                type = RTN_BROADCAST;
         else if (ipv4_is_multicast(fl->fl4_dst))
-                res->type = RTN_MULTICAST;
+                type = RTN_MULTICAST;
         else if (ipv4_is_zeronet(fl->fl4_dst))
                 return ERR_PTR(-EINVAL);
 
@@ -2346,10 +2348,10 @@ static struct rtable *__mkroute_output(struct fib_result *res,
         if (!in_dev)
                 return ERR_PTR(-EINVAL);
 
-        if (res->type == RTN_BROADCAST) {
+        if (type == RTN_BROADCAST) {
                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
-                res->fi = NULL;
-        } else if (res->type == RTN_MULTICAST) {
+                fi = NULL;
+        } else if (type == RTN_MULTICAST) {
                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
                 if (!ip_check_mc(in_dev, oldflp->fl4_dst, oldflp->fl4_src,
                                  oldflp->proto))
@@ -2358,8 +2360,8 @@ static struct rtable *__mkroute_output(struct fib_result *res,
                  * default one, but do not gateway in this case.
                  * Yes, it is hack.
                  */
-                if (res->fi && res->prefixlen < 4)
-                        res->fi = NULL;
+                if (fi && res->prefixlen < 4)
+                        fi = NULL;
         }
 
         rth = rt_dst_alloc(IN_DEV_CONF_GET(in_dev, NOPOLICY),
@@ -2399,7 +2401,7 @@ static struct rtable *__mkroute_output(struct fib_result *res,
                         RT_CACHE_STAT_INC(out_slow_mc);
                 }
 #ifdef CONFIG_IP_MROUTE
-                if (res->type == RTN_MULTICAST) {
+                if (type == RTN_MULTICAST) {
                         if (IN_DEV_MFORWARD(in_dev) &&
                             !ipv4_is_local_multicast(oldflp->fl4_dst)) {
                                 rth->dst.input = ip_mr_input;
@@ -2409,7 +2411,7 @@ static struct rtable *__mkroute_output(struct fib_result *res,
 #endif
         }
 
-        rt_set_nexthop(rth, res, 0);
+        rt_set_nexthop(rth, res, fi, type, 0);
 
         rth->rt_flags = flags;
         return rth;