[PATCH bpf-next v4 2/9] net: ip: make ip_route_input_mc() return drop reason

[Menglong Dong]

Make ip_route_input_mc() return drop reason, and adjust the call of it
in ip_route_input_rcu().

Signed-off-by: Menglong Dong <dong...@chinatelecom.cn>
---
 net/ipv4/route.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3e7a3e947b7d..e579fe5bd3d3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1696,8 +1696,9 @@ int ip_mc_validate_source(struct sk_buff *skb, __be32 
daddr, __be32 saddr,
 }
 
 /* called in rcu_read_lock() section */
-static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-                            dscp_t dscp, struct net_device *dev, int our)
+static enum skb_drop_reason
+ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+                 dscp_t dscp, struct net_device *dev, int our)
 {
        struct in_device *in_dev = __in_dev_get_rcu(dev);
        unsigned int flags = RTCF_MULTICAST;
@@ -1708,7 +1709,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 
daddr, __be32 saddr,
        err = ip_mc_validate_source(skb, daddr, saddr, dscp, dev, in_dev,
                                    &itag);
        if (err)
-               return err;
+               return SKB_DROP_REASON_NOT_SPECIFIED;
 
        if (our)
                flags |= RTCF_LOCAL;
@@ -1719,7 +1720,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 
daddr, __be32 saddr,
        rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
                           false);
        if (!rth)
-               return -ENOBUFS;
+               return SKB_DROP_REASON_NOMEM;
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
        rth->dst.tclassid = itag;
@@ -1735,7 +1736,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 
daddr, __be32 saddr,
 
        skb_dst_drop(skb);
        skb_dst_set(skb, &rth->dst);
-       return 0;
+       return SKB_NOT_DROPPED_YET;
 }
 
 
@@ -2433,12 +2434,12 @@ static int ip_route_input_rcu(struct sk_buff *skb, 
__be32 daddr, __be32 saddr,
         * route cache entry is created eventually.
         */
        if (ipv4_is_multicast(daddr)) {
+               enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
                struct in_device *in_dev = __in_dev_get_rcu(dev);
                int our = 0;
-               int err = -EINVAL;
 
                if (!in_dev)
-                       return err;
+                       return -EINVAL;
                our = ip_check_mc_rcu(in_dev, daddr, saddr,
                                      ip_hdr(skb)->protocol);
 
@@ -2459,10 +2460,10 @@ static int ip_route_input_rcu(struct sk_buff *skb, 
__be32 daddr, __be32 saddr,
                     IN_DEV_MFORWARD(in_dev))
 #endif
                   ) {
-                       err = ip_route_input_mc(skb, daddr, saddr, dscp, dev,
-                                               our);
+                       reason = ip_route_input_mc(skb, daddr, saddr, dscp,
+                                                  dev, our);
                }
-               return err;
+               return reason ? -EINVAL : 0;
        }
 
        return ip_route_input_slow(skb, daddr, saddr, dscp, dev, res);
-- 
2.39.5