Merge branch 'net-prefer-listeners-bound-to-an-address'

Peter Oskolkov says:

====================
net: prefer listeners bound to an address

A relatively common use case is to have several IPs configured
on a host, and have different listeners for each of them. We would
like to add a "catch all" listener on addr_any, to match incoming
connections not served by any of the listeners bound to a specific
address.

However, port-only lookups can match addr_any sockets when sockets
listening on specific addresses are present if so_reuseport flag
is set. This patchset eliminates lookups into port-only hashtable,
as lookups by (addr,port) tuple are easily available.

In a future patchset I plan to explore whether it is possible
to remove port-only hashtables completely: additional refactoring
will be required, as some non-lookup code uses the hashtables.
====================

Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 54 insertions, 215 deletions

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 13890d5bfc34..cd03ab42705b 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -234,24 +234,16 @@ static inline int compute_score(struct sock *sk, struct net *net,
 				const int dif, const int sdif, bool exact_dif)
 {
 	int score = -1;
-	struct inet_sock *inet = inet_sk(sk);
-	bool dev_match;
 
-	if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
+	if (net_eq(sock_net(sk), net) && sk->sk_num == hnum &&
 			!ipv6_only_sock(sk)) {
-		__be32 rcv_saddr = inet->inet_rcv_saddr;
-		score = sk->sk_family == PF_INET ? 2 : 1;
-		if (rcv_saddr) {
-			if (rcv_saddr != daddr)
-				return -1;
-			score += 4;
-		}
-		dev_match = inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
-						 dif, sdif);
-		if (!dev_match)
+		if (sk->sk_rcv_saddr != daddr)
+			return -1;
+
+		if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 			return -1;
-		score += 4;
 
+		score = sk->sk_family == PF_INET ? 2 : 1;
 		if (sk->sk_incoming_cpu == raw_smp_processor_id())
 			score++;
 	}
@@ -307,26 +299,12 @@ struct sock *__inet_lookup_listener(struct net *net,
 				    const __be32 daddr, const unsigned short hnum,
 				    const int dif, const int sdif)
 {
-	unsigned int hash = inet_lhashfn(net, hnum);
-	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
-	bool exact_dif = inet_exact_dif_match(net, skb);
 	struct inet_listen_hashbucket *ilb2;
-	struct sock *sk, *result = NULL;
-	int score, hiscore = 0;
+	struct sock *result = NULL;
 	unsigned int hash2;
-	u32 phash = 0;
-
-	if (ilb->count <= 10 || !hashinfo->lhash2)
-		goto port_lookup;
-
-	/* Too many sk in the ilb bucket (which is hashed by port alone).
-	 * Try lhash2 (which is hashed by port and addr) instead.
-	 */
 
 	hash2 = ipv4_portaddr_hash(net, daddr, hnum);
 	ilb2 = inet_lhash2_bucket(hashinfo, hash2);
-	if (ilb2->count > ilb->count)
-		goto port_lookup;
 
 	result = inet_lhash2_lookup(net, ilb2, skb, doff,
 				    saddr, sport, daddr, hnum,
@@ -335,34 +313,12 @@ struct sock *__inet_lookup_listener(struct net *net,
 		goto done;
 
 	/* Lookup lhash2 with INADDR_ANY */
-
 	hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
 	ilb2 = inet_lhash2_bucket(hashinfo, hash2);
-	if (ilb2->count > ilb->count)
-		goto port_lookup;
 
 	result = inet_lhash2_lookup(net, ilb2, skb, doff,
-				    saddr, sport, daddr, hnum,
+				    saddr, sport, htonl(INADDR_ANY), hnum,
 				    dif, sdif);
-	goto done;
-
-port_lookup:
-	sk_for_each_rcu(sk, &ilb->head) {
-		score = compute_score(sk, net, hnum, daddr,
-				      dif, sdif, exact_dif);
-		if (score > hiscore) {
-			if (sk->sk_reuseport) {
-				phash = inet_ehashfn(net, daddr, hnum,
-						     saddr, sport);
-				result = reuseport_select_sock(sk, phash,
-							       skb, doff);
-				if (result)
-					goto done;
-			}
-			result = sk;
-			hiscore = score;
-		}
-	}
 done:
 	if (unlikely(IS_ERR(result)))
 		return NULL;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index aff2a8e99e01..3fb0ed5e4789 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -380,15 +380,12 @@ static int compute_score(struct sock *sk, struct net *net,
 	    ipv6_only_sock(sk))
 		return -1;
 
-	score = (sk->sk_family == PF_INET) ? 2 : 1;
-	inet = inet_sk(sk);
+	if (sk->sk_rcv_saddr != daddr)
+		return -1;
 
-	if (inet->inet_rcv_saddr) {
-		if (inet->inet_rcv_saddr != daddr)
-			return -1;
-		score += 4;
-	}
+	score = (sk->sk_family == PF_INET) ? 2 : 1;
 
+	inet = inet_sk(sk);
 	if (inet->inet_daddr) {
 		if (inet->inet_daddr != saddr)
 			return -1;
@@ -464,65 +461,30 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 		__be16 sport, __be32 daddr, __be16 dport, int dif,
 		int sdif, struct udp_table *udptable, struct sk_buff *skb)
 {
-	struct sock *sk, *result;
+	struct sock *result;
 	unsigned short hnum = ntohs(dport);
-	unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
-	struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
+	unsigned int hash2, slot2;
+	struct udp_hslot *hslot2;
 	bool exact_dif = udp_lib_exact_dif_match(net, skb);
-	int score, badness;
-	u32 hash = 0;
 
-	if (hslot->count > 10) {
-		hash2 = ipv4_portaddr_hash(net, daddr, hnum);
+	hash2 = ipv4_portaddr_hash(net, daddr, hnum);
+	slot2 = hash2 & udptable->mask;
+	hslot2 = &udptable->hash2[slot2];
+
+	result = udp4_lib_lookup2(net, saddr, sport,
+				  daddr, hnum, dif, sdif,
+				  exact_dif, hslot2, skb);
+	if (!result) {
+		hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
 		slot2 = hash2 & udptable->mask;
 		hslot2 = &udptable->hash2[slot2];
-		if (hslot->count < hslot2->count)
-			goto begin;
 
 		result = udp4_lib_lookup2(net, saddr, sport,
-					  daddr, hnum, dif, sdif,
+					  htonl(INADDR_ANY), hnum, dif, sdif,
 					  exact_dif, hslot2, skb);
-		if (!result) {
-			unsigned int old_slot2 = slot2;
-			hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
-			slot2 = hash2 & udptable->mask;
-			/* avoid searching the same slot again. */
-			if (unlikely(slot2 == old_slot2))
-				return result;
-
-			hslot2 = &udptable->hash2[slot2];
-			if (hslot->count < hslot2->count)
-				goto begin;
-
-			result = udp4_lib_lookup2(net, saddr, sport,
-						  daddr, hnum, dif, sdif,
-						  exact_dif, hslot2, skb);
-		}
-		if (unlikely(IS_ERR(result)))
-			return NULL;
-		return result;
-	}
-begin:
-	result = NULL;
-	badness = 0;
-	sk_for_each_rcu(sk, &hslot->head) {
-		score = compute_score(sk, net, saddr, sport,
-				      daddr, hnum, dif, sdif, exact_dif);
-		if (score > badness) {
-			if (sk->sk_reuseport) {
-				hash = udp_ehashfn(net, daddr, hnum,
-						   saddr, sport);
-				result = reuseport_select_sock(sk, hash, skb,
-							sizeof(struct udphdr));
-				if (unlikely(IS_ERR(result)))
-					return NULL;
-				if (result)
-					return result;
-			}
-			result = sk;
-			badness = score;
-		}
 	}
+	if (unlikely(IS_ERR(result)))
+		return NULL;
 	return result;
 }
 EXPORT_SYMBOL_GPL(__udp4_lib_lookup);
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 5eeeba7181a1..f3515ebe9b3a 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -99,23 +99,16 @@ static inline int compute_score(struct sock *sk, struct net *net,
 				const int dif, const int sdif, bool exact_dif)
 {
 	int score = -1;
-	bool dev_match;
 
 	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 	    sk->sk_family == PF_INET6) {
+		if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
+			return -1;
 
-		score = 1;
-		if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
-			if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
-				return -1;
-			score++;
-		}
-		dev_match = inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
-						 dif, sdif);
-		if (!dev_match)
+		if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 			return -1;
-		score++;
 
+		score = 1;
 		if (sk->sk_incoming_cpu == raw_smp_processor_id())
 			score++;
 	}
@@ -164,26 +157,12 @@ struct sock *inet6_lookup_listener(struct net *net,
 		const __be16 sport, const struct in6_addr *daddr,
 		const unsigned short hnum, const int dif, const int sdif)
 {
-	unsigned int hash = inet_lhashfn(net, hnum);
-	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
-	bool exact_dif = inet6_exact_dif_match(net, skb);
 	struct inet_listen_hashbucket *ilb2;
-	struct sock *sk, *result = NULL;
-	int score, hiscore = 0;
+	struct sock *result = NULL;
 	unsigned int hash2;
-	u32 phash = 0;
-
-	if (ilb->count <= 10 || !hashinfo->lhash2)
-		goto port_lookup;
-
-	/* Too many sk in the ilb bucket (which is hashed by port alone).
-	 * Try lhash2 (which is hashed by port and addr) instead.
-	 */
 
 	hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 	ilb2 = inet_lhash2_bucket(hashinfo, hash2);
-	if (ilb2->count > ilb->count)
-		goto port_lookup;
 
 	result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 				     saddr, sport, daddr, hnum,
@@ -192,33 +171,12 @@ struct sock *inet6_lookup_listener(struct net *net,
 		goto done;
 
 	/* Lookup lhash2 with in6addr_any */
-
 	hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 	ilb2 = inet_lhash2_bucket(hashinfo, hash2);
-	if (ilb2->count > ilb->count)
-		goto port_lookup;
 
 	result = inet6_lhash2_lookup(net, ilb2, skb, doff,
-				     saddr, sport, daddr, hnum,
+				     saddr, sport, &in6addr_any, hnum,
 				     dif, sdif);
-	goto done;
-
-port_lookup:
-	sk_for_each(sk, &ilb->head) {
-		score = compute_score(sk, net, hnum, daddr, dif, sdif, exact_dif);
-		if (score > hiscore) {
-			if (sk->sk_reuseport) {
-				phash = inet6_ehashfn(net, daddr, hnum,
-						      saddr, sport);
-				result = reuseport_select_sock(sk, phash,
-							       skb, doff);
-				if (result)
-					goto done;
-			}
-			result = sk;
-			hiscore = score;
-		}
-	}
 done:
 	if (unlikely(IS_ERR(result)))
 		return NULL;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 09cba4cfe31f..9cbf363172bd 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -125,6 +125,9 @@ static int compute_score(struct sock *sk, struct net *net,
 	    sk->sk_family != PF_INET6)
 		return -1;
 
+	if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
+		return -1;
+
 	score = 0;
 	inet = inet_sk(sk);
 
@@ -134,12 +137,6 @@ static int compute_score(struct sock *sk, struct net *net,
 		score++;
 	}
 
-	if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
-		if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
-			return -1;
-		score++;
-	}
-
 	if (!ipv6_addr_any(&sk->sk_v6_daddr)) {
 		if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr))
 			return -1;
@@ -197,66 +194,32 @@ struct sock *__udp6_lib_lookup(struct net *net,
 			       int dif, int sdif, struct udp_table *udptable,
 			       struct sk_buff *skb)
 {
-	struct sock *sk, *result;
 	unsigned short hnum = ntohs(dport);
-	unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
-	struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
+	unsigned int hash2, slot2;
+	struct udp_hslot *hslot2;
+	struct sock *result;
 	bool exact_dif = udp6_lib_exact_dif_match(net, skb);
-	int score, badness;
-	u32 hash = 0;
 
-	if (hslot->count > 10) {
-		hash2 = ipv6_portaddr_hash(net, daddr, hnum);
+	hash2 = ipv6_portaddr_hash(net, daddr, hnum);
+	slot2 = hash2 & udptable->mask;
+	hslot2 = &udptable->hash2[slot2];
+
+	result = udp6_lib_lookup2(net, saddr, sport,
+				  daddr, hnum, dif, sdif, exact_dif,
+				  hslot2, skb);
+	if (!result) {
+		hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 		slot2 = hash2 & udptable->mask;
+
 		hslot2 = &udptable->hash2[slot2];
-		if (hslot->count < hslot2->count)
-			goto begin;
 
 		result = udp6_lib_lookup2(net, saddr, sport,
-					  daddr, hnum, dif, sdif, exact_dif,
-					  hslot2, skb);
-		if (!result) {
-			unsigned int old_slot2 = slot2;
-			hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
-			slot2 = hash2 & udptable->mask;
-			/* avoid searching the same slot again. */
-			if (unlikely(slot2 == old_slot2))
-				return result;
-
-			hslot2 = &udptable->hash2[slot2];
-			if (hslot->count < hslot2->count)
-				goto begin;
-
-			result = udp6_lib_lookup2(net, saddr, sport,
-						  daddr, hnum, dif, sdif,
-						  exact_dif, hslot2,
-						  skb);
-		}
-		if (unlikely(IS_ERR(result)))
-			return NULL;
-		return result;
-	}
-begin:
-	result = NULL;
-	badness = -1;
-	sk_for_each_rcu(sk, &hslot->head) {
-		score = compute_score(sk, net, saddr, sport, daddr, hnum, dif,
-				      sdif, exact_dif);
-		if (score > badness) {
-			if (sk->sk_reuseport) {
-				hash = udp6_ehashfn(net, daddr, hnum,
-						    saddr, sport);
-				result = reuseport_select_sock(sk, hash, skb,
-							sizeof(struct udphdr));
-				if (unlikely(IS_ERR(result)))
-					return NULL;
-				if (result)
-					return result;
-			}
-			result = sk;
-			badness = score;
-		}
+					  &in6addr_any, hnum, dif, sdif,
+					  exact_dif, hslot2,
+					  skb);
 	}
+	if (unlikely(IS_ERR(result)))
+		return NULL;
 	return result;
 }
 EXPORT_SYMBOL_GPL(__udp6_lib_lookup);