Commit 358105ab authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'tcp-dccp-refine-source-port-selection' 

Eric Dumazet says:

====================
tcp/dccp: refine source port selection

This patch series leverages IP_LOCAL_PORT_RANGE option
to no longer favor even source port selection at connect() time.

This should lower time taken by connect() for hosts having
many active connections to the same destination.
====================

Link: https://lore.kernel.org/r/20231214192939.1962891-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 758a8d5b 20718485

include/net/ip.h

+1 −1
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ static inline void inet_get_local_port_range(const struct net *net, int *low, in 
	*low = range & 0xffff;

	*high = range >> 16;

}

void inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high);

bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high);



#ifdef CONFIG_SYSCTL

static inline bool inet_is_local_reserved_port(struct net *net, unsigned short port)

net/ipv4/inet_connection_sock.c

+16 −5
Original line number Diff line number Diff line
@@ -117,16 +117,25 @@ bool inet_rcv_saddr_any(const struct sock *sk) 
	return !sk->sk_rcv_saddr;

}



void inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)

/**

 *	inet_sk_get_local_port_range - fetch ephemeral ports range

 *	@sk: socket

 *	@low: pointer to low port

 *	@high: pointer to high port

 *

 *	Fetch netns port range (/proc/sys/net/ipv4/ip_local_port_range)

 *	Range can be overridden if socket got IP_LOCAL_PORT_RANGE option.

 *	Returns true if IP_LOCAL_PORT_RANGE was set on this socket.

 */

bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)

{

	const struct inet_sock *inet = inet_sk(sk);

	const struct net *net = sock_net(sk);

	int lo, hi, sk_lo, sk_hi;

	bool local_range = false;

	u32 sk_range;



	inet_get_local_port_range(net, &lo, &hi);

	inet_get_local_port_range(sock_net(sk), &lo, &hi);



	sk_range = READ_ONCE(inet->local_port_range);

	sk_range = READ_ONCE(inet_sk(sk)->local_port_range);

	if (unlikely(sk_range)) {

		sk_lo = sk_range & 0xffff;

		sk_hi = sk_range >> 16;
@@ -135,10 +144,12 @@ void inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high) 
			lo = sk_lo;

		if (lo <= sk_hi && sk_hi <= hi)

			hi = sk_hi;

		local_range = true;

	}



	*low = lo;

	*high = hi;

	return local_range;

}

EXPORT_SYMBOL(inet_sk_get_local_port_range);

net/ipv4/inet_hashtables.c

+16 −11
Original line number Diff line number Diff line
@@ -1012,7 +1012,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
	bool tb_created = false;

	u32 remaining, offset;

	int ret, i, low, high;

	int l3mdev;

	bool local_ports;

	int step, l3mdev;

	u32 index;



	if (port) {
@@ -1024,10 +1025,12 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 


	l3mdev = inet_sk_bound_l3mdev(sk);



	inet_sk_get_local_port_range(sk, &low, &high);

	local_ports = inet_sk_get_local_port_range(sk, &low, &high);

	step = local_ports ? 1 : 2;



	high++; /* [32768, 60999] -> [32768, 61000[ */

	remaining = high - low;

	if (likely(remaining > 1))

	if (!local_ports && remaining > 1)

		remaining &= ~1U;



	get_random_sleepable_once(table_perturb,
@@ -1040,10 +1043,11 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
	/* In first pass we try ports of @low parity.

	 * inet_csk_get_port() does the opposite choice.

	 */

	if (!local_ports)

		offset &= ~1U;

other_parity_scan:

	port = low + offset;

	for (i = 0; i < remaining; i += 2, port += 2) {

	for (i = 0; i < remaining; i += step, port += step) {

		if (unlikely(port >= high))

			port -= remaining;

		if (inet_is_local_reserved_port(net, port))
@@ -1083,10 +1087,11 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
		cond_resched();

	}



	if (!local_ports) {

		offset++;

		if ((offset & 1) && remaining > 1)

			goto other_parity_scan;



	}

	return -EADDRNOTAVAIL;



ok:
@@ -1109,8 +1114,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
	 * on low contention the randomness is maximal and on high contention

	 * it may be inexistent.

	 */

	i = max_t(int, i, get_random_u32_below(8) * 2);

	WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);

	i = max_t(int, i, get_random_u32_below(8) * step);

	WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + step);



	/* Head lock still held and bh's disabled */

	inet_bind_hash(sk, tb, tb2, port);