[UDP]: Revert 2-pass hashing changes.

This reverts changesets:

6aaf47fa48d3c44280810b1b470261d340e4ed87
b7b5f487ab39bc10ed0694af35651a03d9cb97ff
de34ed91c4ffa4727964a832c46e624dd1495cf5
fc038410b4b1643766f8033f4940bcdb1dace633

There are still some correctness issues recently
discovered which do not have a known fix that doesn't
involve doing a full hash table scan on port bind.

So revert for now.

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

1 files changed, 68 insertions, 173 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5da703e699d..facb7e29304 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -114,36 +114,14 @@ DEFINE_RWLOCK(udp_hash_lock);
 
 static int udp_port_rover;
 
-/*
- * Note about this hash function :
- * Typical use is probably daddr = 0, only dport is going to vary hash
- */
-static inline unsigned int udp_hash_port(__u16 port)
-{
-	return port;
-}
-
-static inline int __udp_lib_port_inuse(unsigned int hash, int port,
-				       const struct sock *this_sk,
-				       struct hlist_head udptable[],
-				       const struct udp_get_port_ops *ops)
+static inline int __udp_lib_lport_inuse(__u16 num, struct hlist_head udptable[])
 {
 	struct sock *sk;
 	struct hlist_node *node;
-	struct inet_sock *inet;
 
-	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {
-		if (sk->sk_hash != hash)
-			continue;
-		inet = inet_sk(sk);
-		if (inet->num != port)
-			continue;
-		if (this_sk) {
-			if (ops->saddr_cmp(sk, this_sk))
-				return 1;
-		} else if (ops->saddr_any(sk))
+	sk_for_each(sk, node, &udptable[num & (UDP_HTABLE_SIZE - 1)])
+		if (sk->sk_hash == num)
 			return 1;
-	}
 	return 0;
 }
 
@@ -154,16 +132,16 @@ static inline int __udp_lib_port_inuse(unsigned int hash, int port,
  *  @snum:        port number to look up
  *  @udptable:    hash list table, must be of UDP_HTABLE_SIZE
  *  @port_rover:  pointer to record of last unallocated port
- *  @ops:         AF-dependent address operations
+ *  @saddr_comp:  AF-dependent comparison of bound local IP addresses
  */
 int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 		       struct hlist_head udptable[], int *port_rover,
-		       const struct udp_get_port_ops *ops)
+		       int (*saddr_comp)(const struct sock *sk1,
+					 const struct sock *sk2 )    )
 {
 	struct hlist_node *node;
 	struct hlist_head *head;
 	struct sock *sk2;
-	unsigned int hash;
 	int    error = 1;
 
 	write_lock_bh(&udp_hash_lock);
@@ -178,8 +156,7 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 		for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
 			int size;
 
-			hash = ops->hash_port_and_rcv_saddr(result, sk);
-			head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
+			head = &udptable[result & (UDP_HTABLE_SIZE - 1)];
 			if (hlist_empty(head)) {
 				if (result > sysctl_local_port_range[1])
 					result = sysctl_local_port_range[0] +
@@ -204,16 +181,7 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 				result = sysctl_local_port_range[0]
 					+ ((result - sysctl_local_port_range[0]) &
 					   (UDP_HTABLE_SIZE - 1));
-			hash = udp_hash_port(result);
-			if (__udp_lib_port_inuse(hash, result,
-						 NULL, udptable, ops))
-				continue;
-			if (ops->saddr_any(sk))
-				break;
-
-			hash = ops->hash_port_and_rcv_saddr(result, sk);
-			if (! __udp_lib_port_inuse(hash, result,
-						   sk, udptable, ops))
+			if (! __udp_lib_lport_inuse(result, udptable))
 				break;
 		}
 		if (i >= (1 << 16) / UDP_HTABLE_SIZE)
@@ -221,40 +189,21 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 gotit:
 		*port_rover = snum = result;
 	} else {
-		hash = udp_hash_port(snum);
-		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
+		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
 
 		sk_for_each(sk2, node, head)
-			if (sk2->sk_hash == hash &&
-			    sk2 != sk &&
-			    inet_sk(sk2)->num == snum &&
-			    (!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) &&
-			    ops->saddr_cmp(sk, sk2))
+			if (sk2->sk_hash == 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_comp)(sk, sk2)                             )
 				goto fail;
-
-		if (!ops->saddr_any(sk)) {
-			hash = ops->hash_port_and_rcv_saddr(snum, sk);
-			head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
-
-			sk_for_each(sk2, node, head)
-				if (sk2->sk_hash == hash &&
-				    sk2 != sk &&
-				    inet_sk(sk2)->num == snum &&
-				    (!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) &&
-				    ops->saddr_cmp(sk, sk2))
-					goto fail;
-		}
 	}
 	inet_sk(sk)->num = snum;
-	sk->sk_hash = hash;
+	sk->sk_hash = snum;
 	if (sk_unhashed(sk)) {
-		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
+		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
 		sk_add_node(sk, head);
 		sock_prot_inc_use(sk->sk_prot);
 	}
@@ -265,12 +214,12 @@ fail:
 }
 
 int udp_get_port(struct sock *sk, unsigned short snum,
-		 const struct udp_get_port_ops *ops)
+			int (*scmp)(const struct sock *, const struct sock *))
 {
-	return  __udp_lib_get_port(sk, snum, udp_hash, &udp_port_rover, ops);
+	return  __udp_lib_get_port(sk, snum, udp_hash, &udp_port_rover, scmp);
 }
 
-static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
+int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
 {
 	struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2);
 
@@ -279,33 +228,9 @@ static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
 		   inet1->rcv_saddr == inet2->rcv_saddr      ));
 }
 
-static int ipv4_rcv_saddr_any(const struct sock *sk)
-{
-	return !inet_sk(sk)->rcv_saddr;
-}
-
-static inline unsigned int ipv4_hash_port_and_addr(__u16 port, __be32 addr)
-{
-	addr ^= addr >> 16;
-	addr ^= addr >> 8;
-	return port ^ addr;
-}
-
-static unsigned int ipv4_hash_port_and_rcv_saddr(__u16 port,
-						 const struct sock *sk)
-{
-	return ipv4_hash_port_and_addr(port, inet_sk(sk)->rcv_saddr);
-}
-
-const struct udp_get_port_ops udp_ipv4_ops = {
-	.saddr_cmp = ipv4_rcv_saddr_equal,
-	.saddr_any = ipv4_rcv_saddr_any,
-	.hash_port_and_rcv_saddr = ipv4_hash_port_and_rcv_saddr,
-};
-
 static inline int udp_v4_get_port(struct sock *sk, unsigned short snum)
 {
-	return udp_get_port(sk, snum, &udp_ipv4_ops);
+	return udp_get_port(sk, snum, ipv4_rcv_saddr_equal);
 }
 
 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
@@ -317,77 +242,63 @@ static struct sock *__udp4_lib_lookup(__be32 saddr, __be16 sport,
 {
 	struct sock *sk, *result = NULL;
 	struct hlist_node *node;
-	unsigned int hash, hashwild;
-	int score, best = -1, hport = ntohs(dport);
-
-	hash = ipv4_hash_port_and_addr(hport, daddr);
-	hashwild = udp_hash_port(hport);
+	unsigned short hnum = ntohs(dport);
+	int badness = -1;
 
 	read_lock(&udp_hash_lock);
-
-lookup:
-
-	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {
+	sk_for_each(sk, node, &udptable[hnum & (UDP_HTABLE_SIZE - 1)]) {
 		struct inet_sock *inet = inet_sk(sk);
 
-		if (sk->sk_hash != hash || ipv6_only_sock(sk) ||
-			inet->num != hport)
-			continue;
-
-		score = (sk->sk_family == PF_INET ? 1 : 0);
-		if (inet->rcv_saddr) {
-			if (inet->rcv_saddr != daddr)
-				continue;
-			score+=2;
-		}
-		if (inet->daddr) {
-			if (inet->daddr != saddr)
-				continue;
-			score+=2;
-		}
-		if (inet->dport) {
-			if (inet->dport != sport)
-				continue;
-			score+=2;
-		}
-		if (sk->sk_bound_dev_if) {
-			if (sk->sk_bound_dev_if != dif)
-				continue;
-			score+=2;
-		}
-		if (score == 9) {
-			result = sk;
-			goto found;
-		} else if (score > best) {
-			result = sk;
-			best = score;
+		if (sk->sk_hash == hnum && !ipv6_only_sock(sk)) {
+			int score = (sk->sk_family == PF_INET ? 1 : 0);
+			if (inet->rcv_saddr) {
+				if (inet->rcv_saddr != daddr)
+					continue;
+				score+=2;
+			}
+			if (inet->daddr) {
+				if (inet->daddr != saddr)
+					continue;
+				score+=2;
+			}
+			if (inet->dport) {
+				if (inet->dport != sport)
+					continue;
+				score+=2;
+			}
+			if (sk->sk_bound_dev_if) {
+				if (sk->sk_bound_dev_if != dif)
+					continue;
+				score+=2;
+			}
+			if (score == 9) {
+				result = sk;
+				break;
+			} else if (score > badness) {
+				result = sk;
+				badness = score;
+			}
 		}
 	}
-
-	if (hash != hashwild) {
-		hash = hashwild;
-		goto lookup;
-	}
-found:
 	if (result)
 		sock_hold(result);
 	read_unlock(&udp_hash_lock);
 	return result;
 }
 
-static inline struct sock *udp_v4_mcast_next(struct sock *sk, unsigned int hnum,
-					     int hport, __be32 loc_addr,
+static inline struct sock *udp_v4_mcast_next(struct sock *sk,
+					     __be16 loc_port, __be32 loc_addr,
 					     __be16 rmt_port, __be32 rmt_addr,
 					     int dif)
 {
 	struct hlist_node *node;
 	struct sock *s = sk;
+	unsigned short hnum = ntohs(loc_port);
 
 	sk_for_each_from(s, node) {
 		struct inet_sock *inet = inet_sk(s);
 
 		if (s->sk_hash != hnum					||
-		    inet->num != hport					||
 		    (inet->daddr && inet->daddr != rmt_addr)		||
 		    (inet->dport != rmt_port && inet->dport)		||
 		    (inet->rcv_saddr && inet->rcv_saddr != loc_addr)	||
@@ -1221,45 +1132,29 @@ static int __udp4_lib_mcast_deliver(struct sk_buff *skb,
 				    __be32 saddr, __be32 daddr,
 				    struct hlist_head udptable[])
 {
-	struct sock *sk, *skw, *sknext;
+	struct sock *sk;
 	int dif;
-	int hport = ntohs(uh->dest);
-	unsigned int hash = ipv4_hash_port_and_addr(hport, daddr);
-	unsigned int hashwild = udp_hash_port(hport);
-
-	dif = skb->dev->ifindex;
 
 	read_lock(&udp_hash_lock);
-
-	sk = sk_head(&udptable[hash & (UDP_HTABLE_SIZE - 1)]);
-	skw = sk_head(&udptable[hashwild & (UDP_HTABLE_SIZE - 1)]);
-
-	sk = udp_v4_mcast_next(sk, hash, hport, daddr, uh->source, saddr, dif);
-	if (!sk) {
-		hash = hashwild;
-		sk = udp_v4_mcast_next(skw, hash, hport, daddr, uh->source,
-			saddr, dif);
-	}
+	sk = sk_head(&udptable[ntohs(uh->dest) & (UDP_HTABLE_SIZE - 1)]);
+	dif = skb->dev->ifindex;
+	sk = udp_v4_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);
 	if (sk) {
+		struct sock *sknext = NULL;
+
 		do {
 			struct sk_buff *skb1 = skb;
-			sknext = udp_v4_mcast_next(sk_next(sk), hash, hport,
-						daddr, uh->source, saddr, dif);
-			if (!sknext && hash != hashwild) {
-				hash = hashwild;
-				sknext = udp_v4_mcast_next(skw, hash, hport,
-					daddr, uh->source, saddr, dif);
-			}
+
+			sknext = udp_v4_mcast_next(sk_next(sk), uh->dest, daddr,
+						   uh->source, saddr, dif);
 			if (sknext)
 				skb1 = skb_clone(skb, GFP_ATOMIC);
 
 			if (skb1) {
 				int ret = udp_queue_rcv_skb(sk, skb1);
 				if (ret > 0)
-					/*
-					 * we should probably re-process
-					 * instead of dropping packets here.
-					 */
+					/* we should probably re-process instead
+					 * of dropping packets here. */
 					kfree_skb(skb1);
 			}
 			sk = sknext;
@@ -1346,7 +1241,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
 		return __udp4_lib_mcast_deliver(skb, uh, saddr, daddr, udptable);
 
 	sk = __udp4_lib_lookup(saddr, uh->source, daddr, uh->dest,
-			       skb->dev->ifindex, udptable);
+			       skb->dev->ifindex, udptable        );
 
 	if (sk != NULL) {
 		int ret = udp_queue_rcv_skb(sk, skb);