ip: Router Alert RCU conversion

Straightforward conversion to RCU.

One rwlock becomes a spinlock, and is static.

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

3 files changed, 18 insertions, 18 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 452f229c380a..9982c97f0bdc 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -62,10 +62,10 @@ struct ip_ra_chain {
         struct ip_ra_chain      *next;
         struct sock             *sk;
         void                    (*destructor)(struct sock *);
+        struct rcu_head         rcu;
 };
 
 extern struct ip_ra_chain *ip_ra_chain;
-extern rwlock_t ip_ra_lock;
 
 /* IP flags. */
 #define IP_CE           0x8000          /* Flag: "Congestion"           */
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index d52c9da644cf..d274078b1665 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -146,7 +146,7 @@
 #include <linux/netlink.h>
 
 /*
- *      Process Router Attention IP option
+ *      Process Router Attention IP option (RFC 2113)
  */
 int ip_call_ra_chain(struct sk_buff *skb)
 {
@@ -155,8 +155,7 @@ int ip_call_ra_chain(struct sk_buff *skb)
         struct sock *last = NULL;
         struct net_device *dev = skb->dev;
 
-        read_lock(&ip_ra_lock);
-        for (ra = ip_ra_chain; ra; ra = ra->next) {
+        for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
                 struct sock *sk = ra->sk;
 
                 /* If socket is bound to an interface, only report
@@ -167,10 +166,8 @@ int ip_call_ra_chain(struct sk_buff *skb)
                      sk->sk_bound_dev_if == dev->ifindex) &&
                     net_eq(sock_net(sk), dev_net(dev))) {
                         if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
-                                if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN)) {
-                                        read_unlock(&ip_ra_lock);
+                                if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
                                         return 1;
-                                }
                         }
                         if (last) {
                                 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
@@ -183,10 +180,8 @@ int ip_call_ra_chain(struct sk_buff *skb)
 
         if (last) {
                 raw_rcv(last, skb);
-                read_unlock(&ip_ra_lock);
                 return 1;
         }
-        read_unlock(&ip_ra_lock);
         return 0;
 }
 
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ce231780a2b1..08b9519a24f4 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -239,7 +239,12 @@ int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc)
    sent to multicast group to reach destination designated router.
  */
 struct ip_ra_chain *ip_ra_chain;
-DEFINE_RWLOCK(ip_ra_lock);
+static DEFINE_SPINLOCK(ip_ra_lock);
+
+static void ip_ra_free_rcu(struct rcu_head *head)
+{
+        kfree(container_of(head, struct ip_ra_chain, rcu));
+}
 
 int ip_ra_control(struct sock *sk, unsigned char on,
                   void (*destructor)(struct sock *))
@@ -251,35 +256,35 @@ int ip_ra_control(struct sock *sk, unsigned char on,
 
         new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;
 
-        write_lock_bh(&ip_ra_lock);
+        spin_lock_bh(&ip_ra_lock);
         for (rap = &ip_ra_chain; (ra = *rap) != NULL; rap = &ra->next) {
                 if (ra->sk == sk) {
                         if (on) {
-                                write_unlock_bh(&ip_ra_lock);
+                                spin_unlock_bh(&ip_ra_lock);
                                 kfree(new_ra);
                                 return -EADDRINUSE;
                         }
-                        *rap = ra->next;
-                        write_unlock_bh(&ip_ra_lock);
+                        rcu_assign_pointer(*rap, ra->next);
+                        spin_unlock_bh(&ip_ra_lock);
 
                         if (ra->destructor)
                                 ra->destructor(sk);
                         sock_put(sk);
-                        kfree(ra);
+                        call_rcu(&ra->rcu, ip_ra_free_rcu);
                         return 0;
                 }
         }
         if (new_ra == NULL) {
-                write_unlock_bh(&ip_ra_lock);
+                spin_unlock_bh(&ip_ra_lock);
                 return -ENOBUFS;
         }
         new_ra->sk = sk;
         new_ra->destructor = destructor;
 
         new_ra->next = ra;
-        *rap = new_ra;
+        rcu_assign_pointer(*rap, new_ra);
         sock_hold(sk);
-        write_unlock_bh(&ip_ra_lock);
+        spin_unlock_bh(&ip_ra_lock);
 
         return 0;
 }