[UDP]: Unify UDPv4 and UDPv6 ->get_port()

This patch creates one common function which is called by
udp_v4_get_port() and udp_v6_get_port(). As a result,
  * duplicated code is removed
  * udp_port_rover and local port lookup can now be removed from udp.h
  * further savings follow since the same function will be used by UDP-Litev4
    and UDP-Litev6

In contrast to the patch sent in response to Yoshifujis comments
(fixed by this variant), the code below also removes the
EXPORT_SYMBOL(udp_port_rover), since udp_port_rover can now remain
local to net/ipv4/udp.c.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 64 insertions, 126 deletions

diff --git a/include/net/udp.h b/include/net/udp.h
index 766fba1369ce..c490a0f662ac 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -30,25 +30,9 @@
 
 #define UDP_HTABLE_SIZE         128
 
-/* udp.c: This needs to be shared by v4 and v6 because the lookup
- *        and hashing code needs to work with different AF's yet
- *        the port space is shared.
- */
 extern struct hlist_head udp_hash[UDP_HTABLE_SIZE];
 extern rwlock_t udp_hash_lock;
 
-extern int udp_port_rover;
-
-static inline int udp_lport_inuse(u16 num)
-{
-        struct sock *sk;
-        struct hlist_node *node;
-
-        sk_for_each(sk, node, &udp_hash[num & (UDP_HTABLE_SIZE - 1)])
-                if (inet_sk(sk)->num == num)
-                        return 1;
-        return 0;
-}
 
 /* Note: this must match 'valbool' in sock_setsockopt */
 #define UDP_CSUM_NOXMIT         1
@@ -63,6 +47,8 @@ extern struct proto udp_prot;
 
 struct sk_buff;
 
+extern int      udp_get_port(struct sock *sk, unsigned short snum,
+                             int (*saddr_cmp)(struct sock *, struct sock *));
 extern void     udp_err(struct sk_buff *, u32);
 
 extern int      udp_sendmsg(struct kiocb *iocb, struct sock *sk,
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 514c1e9ae810..7552b50bcd84 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -118,14 +118,34 @@ DEFINE_SNMP_STAT(struct udp_mib, udp_statistics) __read_mostly;
 struct hlist_head udp_hash[UDP_HTABLE_SIZE];
 DEFINE_RWLOCK(udp_hash_lock);
 
-/* Shared by v4/v6 udp. */
+/* Shared by v4/v6 udp_get_port */
 int udp_port_rover;
 
-static int udp_v4_get_port(struct sock *sk, unsigned short snum)
+static inline int udp_lport_inuse(u16 num)
 {
+        struct sock *sk;
         struct hlist_node *node;
+
+        sk_for_each(sk, node, &udp_hash[num & (UDP_HTABLE_SIZE - 1)])
+                if (inet_sk(sk)->num == num)
+                        return 1;
+        return 0;
+}
+
+/**
+ *  udp_get_port  -  common port lookup for IPv4 and IPv6
+ *
+ *  @sk:          socket struct in question
+ *  @snum:        port number to look up
+ *  @saddr_comp:  AF-dependent comparison of bound local IP addresses
+ */
+int udp_get_port(struct sock *sk, unsigned short snum,
+                 int (*saddr_cmp)(struct sock *sk1, struct sock *sk2))
+{
+        struct hlist_node *node;
+        struct hlist_head *head;
         struct sock *sk2;
-        struct inet_sock *inet = inet_sk(sk);
+        int    error = 1;
 
         write_lock_bh(&udp_hash_lock);
         if (snum == 0) {
@@ -137,11 +157,10 @@ static int udp_v4_get_port(struct sock *sk, unsigned short snum)
                 best_size_so_far = 32767;
                 best = result = udp_port_rover;
                 for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
-                        struct hlist_head *list;
                         int size;
 
-                        list = &udp_hash[result & (UDP_HTABLE_SIZE - 1)];
-                        if (hlist_empty(list)) {
+                        head = &udp_hash[result & (UDP_HTABLE_SIZE - 1)];
+                        if (hlist_empty(head)) {
                                 if (result > sysctl_local_port_range[1])
                                         result = sysctl_local_port_range[0] +
                                                 ((result - sysctl_local_port_range[0]) &
@@ -149,12 +168,11 @@ static int udp_v4_get_port(struct sock *sk, unsigned short snum)
                                 goto gotit;
                         }
                         size = 0;
-                        sk_for_each(sk2, node, list)
-                                if (++size >= best_size_so_far)
-                                        goto next;
-                        best_size_so_far = size;
-                        best = result;
-                next:;
+                        sk_for_each(sk2, node, head)
+                                if (++size < best_size_so_far) {
+                                        best_size_so_far = size;
+                                        best = result;
+                                }
                 }
                 result = best;
                 for(i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++, result += UDP_HTABLE_SIZE) {
@@ -170,38 +188,44 @@ static int udp_v4_get_port(struct sock *sk, unsigned short snum)
 gotit:
                 udp_port_rover = snum = result;
         } else {
-                sk_for_each(sk2, node,
-                            &udp_hash[snum & (UDP_HTABLE_SIZE - 1)]) {
-                        struct inet_sock *inet2 = inet_sk(sk2);
-
-                        if (inet2->num == snum &&
-                            sk2 != sk &&
-                            !ipv6_only_sock(sk2) &&
-                            (!sk2->sk_bound_dev_if ||
-                             !sk->sk_bound_dev_if ||
-                             sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                            (!inet2->rcv_saddr ||
-                             !inet->rcv_saddr ||
-                             inet2->rcv_saddr == inet->rcv_saddr) &&
-                            (!sk2->sk_reuse || !sk->sk_reuse))
+                head = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];
+
+                sk_for_each(sk2, node, head)
+                        if (inet_sk(sk2)->num == snum                        &&
+                            sk2 != sk                                        &&
+                            (!sk2->sk_reuse        || !sk->sk_reuse)         &&
+                            (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
+                             || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
+                            (*saddr_cmp)(sk, sk2)                              )
                                 goto fail;
-                }
         }
-        inet->num = snum;
+        inet_sk(sk)->num = snum;
         if (sk_unhashed(sk)) {
-                struct hlist_head *h = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];
-
-                sk_add_node(sk, h);
+                head = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];
+                sk_add_node(sk, head);
                 sock_prot_inc_use(sk->sk_prot);
         }
-        write_unlock_bh(&udp_hash_lock);
-        return 0;
-
+        error = 0;
 fail:
         write_unlock_bh(&udp_hash_lock);
-        return 1;
+        return error;
+}
+
+static inline int  ipv4_rcv_saddr_equal(struct sock *sk1, struct sock *sk2)
+{
+        struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2);
+
+        return  ( !ipv6_only_sock(sk2)  &&
+                  (!inet1->rcv_saddr || !inet2->rcv_saddr ||
+                   inet1->rcv_saddr == inet2->rcv_saddr      ));
+}
+
+static inline int udp_v4_get_port(struct sock *sk, unsigned short snum)
+{
+        return udp_get_port(sk, snum, ipv4_rcv_saddr_equal);
 }
 
+
 static void udp_v4_hash(struct sock *sk)
 {
         BUG();
@@ -1596,7 +1620,7 @@ EXPORT_SYMBOL(udp_disconnect);
 EXPORT_SYMBOL(udp_hash);
 EXPORT_SYMBOL(udp_hash_lock);
 EXPORT_SYMBOL(udp_ioctl);
-EXPORT_SYMBOL(udp_port_rover);
+EXPORT_SYMBOL(udp_get_port);
 EXPORT_SYMBOL(udp_prot);
 EXPORT_SYMBOL(udp_sendmsg);
 EXPORT_SYMBOL(udp_poll);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b9cc55ccb000..9662561701d1 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -61,81 +61,9 @@
 
 DEFINE_SNMP_STAT(struct udp_mib, udp_stats_in6) __read_mostly;
 
-/* Grrr, addr_type already calculated by caller, but I don't want
- * to add some silly "cookie" argument to this method just for that.
- */
-static int udp_v6_get_port(struct sock *sk, unsigned short snum)
+static inline int udp_v6_get_port(struct sock *sk, unsigned short snum)
 {
-        struct sock *sk2;
-        struct hlist_node *node;
-
-        write_lock_bh(&udp_hash_lock);
-        if (snum == 0) {
-                int best_size_so_far, best, result, i;
-
-                if (udp_port_rover > sysctl_local_port_range[1] ||
-                    udp_port_rover < sysctl_local_port_range[0])
-                        udp_port_rover = sysctl_local_port_range[0];
-                best_size_so_far = 32767;
-                best = result = udp_port_rover;
-                for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
-                        int size;
-                        struct hlist_head *list;
-
-                        list = &udp_hash[result & (UDP_HTABLE_SIZE - 1)];
-                        if (hlist_empty(list)) {
-                                if (result > sysctl_local_port_range[1])
-                                        result = sysctl_local_port_range[0] +
-                                                ((result - sysctl_local_port_range[0]) &
-                                                 (UDP_HTABLE_SIZE - 1));
-                                goto gotit;
-                        }
-                        size = 0;
-                        sk_for_each(sk2, node, list)
-                                if (++size >= best_size_so_far)
-                                        goto next;
-                        best_size_so_far = size;
-                        best = result;
-                next:;
-                }
-                result = best;
-                for(i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++, result += UDP_HTABLE_SIZE) {
-                        if (result > sysctl_local_port_range[1])
-                                result = sysctl_local_port_range[0]
-                                        + ((result - sysctl_local_port_range[0]) &
-                                           (UDP_HTABLE_SIZE - 1));
-                        if (!udp_lport_inuse(result))
-                                break;
-                }
-                if (i >= (1 << 16) / UDP_HTABLE_SIZE)
-                        goto fail;
-gotit:
-                udp_port_rover = snum = result;
-        } else {
-                sk_for_each(sk2, node,
-                            &udp_hash[snum & (UDP_HTABLE_SIZE - 1)]) {
-                        if (inet_sk(sk2)->num == snum &&
-                            sk2 != sk &&
-                            (!sk2->sk_bound_dev_if ||
-                             !sk->sk_bound_dev_if ||
-                             sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                            (!sk2->sk_reuse || !sk->sk_reuse) &&
-                            ipv6_rcv_saddr_equal(sk, sk2))
-                                goto fail;
-                }
-        }
-
-        inet_sk(sk)->num = snum;
-        if (sk_unhashed(sk)) {
-                sk_add_node(sk, &udp_hash[snum & (UDP_HTABLE_SIZE - 1)]);
-                sock_prot_inc_use(sk->sk_prot);
-        }
-        write_unlock_bh(&udp_hash_lock);
-        return 0;
-
-fail:
-        write_unlock_bh(&udp_hash_lock);
-        return 1;
+        return udp_get_port(sk, snum, ipv6_rcv_saddr_equal);
 }
 
 static void udp_v6_hash(struct sock *sk)