ipv6: some RCU conversions

ICMP and ND are not fast path, but still we can avoid changing idev
refcount, using RCU.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 21 insertions, 35 deletions

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 11900417b1cc..2b59154c65d3 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -490,7 +490,8 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
                 goto out_dst_release;
         }
 
-        idev = in6_dev_get(skb->dev);
+        rcu_read_lock();
+        idev = __in6_dev_get(skb->dev);
 
         err = ip6_append_data(sk, icmpv6_getfrag, &msg,
                               len + sizeof(struct icmp6hdr),
@@ -500,19 +501,16 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
         if (err) {
                 ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTERRORS);
                 ip6_flush_pending_frames(sk);
-                goto out_put;
+        } else {
+                err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
+                                                 len + sizeof(struct icmp6hdr));
         }
-        err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, len + sizeof(struct icmp6hdr));
-
-out_put:
-        if (likely(idev != NULL))
-                in6_dev_put(idev);
+        rcu_read_unlock();
 out_dst_release:
         dst_release(dst);
 out:
         icmpv6_xmit_unlock(sk);
 }
-
 EXPORT_SYMBOL(icmpv6_send);
 
 static void icmpv6_echo_reply(struct sk_buff *skb)
@@ -569,7 +567,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
         if (hlimit < 0)
                 hlimit = ip6_dst_hoplimit(dst);
 
-        idev = in6_dev_get(skb->dev);
+        idev = __in6_dev_get(skb->dev);
 
         msg.skb = skb;
         msg.offset = 0;
@@ -583,13 +581,10 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
         if (err) {
                 ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTERRORS);
                 ip6_flush_pending_frames(sk);
-                goto out_put;
+        } else {
+                err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
+                                                 skb->len + sizeof(struct icmp6hdr));
         }
-        err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, skb->len + sizeof(struct icmp6hdr));
-
-out_put:
-        if (likely(idev != NULL))
-                in6_dev_put(idev);
         dst_release(dst);
 out:
         icmpv6_xmit_unlock(sk);
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 9da6e02eaaeb..1f52dd257631 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -533,7 +533,8 @@ void ndisc_send_skb(struct sk_buff *skb,
 
         skb_dst_set(skb, dst);
 
-        idev = in6_dev_get(dst->dev);
+        rcu_read_lock();
+        idev = __in6_dev_get(dst->dev);
         IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
 
         err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL, dst->dev,
@@ -543,8 +544,7 @@ void ndisc_send_skb(struct sk_buff *skb,
                 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
         }
 
-        if (likely(idev != NULL))
-                in6_dev_put(idev);
+        rcu_read_unlock();
 }
 
 EXPORT_SYMBOL(ndisc_send_skb);
@@ -1039,7 +1039,7 @@ static void ndisc_recv_rs(struct sk_buff *skb)
         if (skb->len < sizeof(*rs_msg))
                 return;
 
-        idev = in6_dev_get(skb->dev);
+        idev = __in6_dev_get(skb->dev);
         if (!idev) {
                 if (net_ratelimit())
                         ND_PRINTK1("ICMP6 RS: can't find in6 device\n");
@@ -1080,7 +1080,7 @@ static void ndisc_recv_rs(struct sk_buff *skb)
                 neigh_release(neigh);
         }
 out:
-        in6_dev_put(idev);
+        return;
 }
 
 static void ndisc_ra_useropt(struct sk_buff *ra, struct nd_opt_hdr *opt)
@@ -1179,7 +1179,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
          *      set the RA_RECV flag in the interface
          */
 
-        in6_dev = in6_dev_get(skb->dev);
+        in6_dev = __in6_dev_get(skb->dev);
         if (in6_dev == NULL) {
                 ND_PRINTK0(KERN_ERR
                            "ICMPv6 RA: can't find inet6 device for %s.\n",
@@ -1188,7 +1188,6 @@ static void ndisc_router_discovery(struct sk_buff *skb)
         }
 
         if (!ndisc_parse_options(opt, optlen, &ndopts)) {
-                in6_dev_put(in6_dev);
                 ND_PRINTK2(KERN_WARNING
                            "ICMP6 RA: invalid ND options\n");
                 return;
@@ -1255,7 +1254,6 @@ static void ndisc_router_discovery(struct sk_buff *skb)
                         ND_PRINTK0(KERN_ERR
                                    "ICMPv6 RA: %s() failed to add default route.\n",
                                    __func__);
-                        in6_dev_put(in6_dev);
                         return;
                 }
 
@@ -1265,7 +1263,6 @@ static void ndisc_router_discovery(struct sk_buff *skb)
                                    "ICMPv6 RA: %s() got default router without neighbour.\n",
                                    __func__);
                         dst_release(&rt->dst);
-                        in6_dev_put(in6_dev);
                         return;
                 }
                 neigh->flags |= NTF_ROUTER;
@@ -1422,7 +1419,6 @@ out:
                 dst_release(&rt->dst);
         else if (neigh)
                 neigh_release(neigh);
-        in6_dev_put(in6_dev);
 }
 
 static void ndisc_redirect_rcv(struct sk_buff *skb)
@@ -1481,13 +1477,11 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
                 return;
         }
 
-        in6_dev = in6_dev_get(skb->dev);
+        in6_dev = __in6_dev_get(skb->dev);
         if (!in6_dev)
                 return;
-        if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_redirects) {
-                in6_dev_put(in6_dev);
+        if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_redirects)
                 return;
-        }
 
         /* RFC2461 8.1:
          *      The IP source address of the Redirect MUST be the same as the current
@@ -1497,7 +1491,6 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
         if (!ndisc_parse_options((u8*)(dest + 1), optlen, &ndopts)) {
                 ND_PRINTK2(KERN_WARNING
                            "ICMPv6 Redirect: invalid ND options\n");
-                in6_dev_put(in6_dev);
                 return;
         }
         if (ndopts.nd_opts_tgt_lladdr) {
@@ -1506,7 +1499,6 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
                 if (!lladdr) {
                         ND_PRINTK2(KERN_WARNING
                                    "ICMPv6 Redirect: invalid link-layer address length\n");
-                        in6_dev_put(in6_dev);
                         return;
                 }
         }
@@ -1518,7 +1510,6 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
                              on_link);
                 neigh_release(neigh);
         }
-        in6_dev_put(in6_dev);
 }
 
 void ndisc_send_redirect(struct sk_buff *skb, struct neighbour *neigh,
@@ -1651,7 +1642,8 @@ void ndisc_send_redirect(struct sk_buff *skb, struct neighbour *neigh,
                                              csum_partial(icmph, len, 0));
 
         skb_dst_set(buff, dst);
-        idev = in6_dev_get(dst->dev);
+        rcu_read_lock();
+        idev = __in6_dev_get(dst->dev);
         IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
         err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, buff, NULL, dst->dev,
                       dst_output);
@@ -1660,8 +1652,7 @@ void ndisc_send_redirect(struct sk_buff *skb, struct neighbour *neigh,
                 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
         }
 
-        if (likely(idev != NULL))
-                in6_dev_put(idev);
+        rcu_read_unlock();
         return;
 
 release: