tcp: bind() use stronger condition for bind_conflict

We must try harder to get unique (addr, port) pairs when
doing port autoselection for sockets with SO_REUSEADDR
option set.

We achieve this by adding a relaxation parameter to
inet_csk_bind_conflict. When 'relax' parameter is off
we return a conflict whenever the current searched
pair (addr, port) is not unique.

This tries to address the problems reported in patch:
	8d238b25b1ec22a73b1c2206f111df2faaff8285
	Revert "tcp: bind() fix when many ports are bound"

Tests where ran for creating and binding(0) many sockets
on 100 IPs. The results are, on average:

	* 60000 sockets, 600 ports / IP:
		* 0.210 s, 620 (IP, port) duplicates without patch
		* 0.219 s, no duplicates with patch
	* 100000 sockets, 1000 ports / IP:
		* 0.371 s, 1720 duplicates without patch
		* 0.373 s, no duplicates with patch
	* 200000 sockets, 2000 ports / IP:
		* 0.766 s, 6900 duplicates without patch
		* 0.768 s, no duplicates with patch
	* 500000 sockets, 5000 ports / IP:
		* 2.227 s, 41500 duplicates without patch
		* 2.284 s, no duplicates with patch

Signed-off-by: Alex Copot <alex.mihai.c@gmail.com>
Signed-off-by: Daniel Baluta <dbaluta@ixiacom.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index dbf9aab34c82..46c9e2ccdf02 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -60,7 +60,7 @@ struct inet_connection_sock_af_ops {
 #endif
         void        (*addr2sockaddr)(struct sock *sk, struct sockaddr *);
         int         (*bind_conflict)(const struct sock *sk,
-                                     const struct inet_bind_bucket *tb);
+                                     const struct inet_bind_bucket *tb, bool relax);
 };
 
 /** inet_connection_sock - INET connection oriented sock
@@ -245,7 +245,7 @@ extern struct request_sock *inet_csk_search_req(const struct sock *sk,
                                                 const __be32 raddr,
                                                 const __be32 laddr);
 extern int inet_csk_bind_conflict(const struct sock *sk,
-                                  const struct inet_bind_bucket *tb);
+                                  const struct inet_bind_bucket *tb, bool relax);
 extern int inet_csk_get_port(struct sock *sk, unsigned short snum);
 
 extern struct dst_entry* inet_csk_route_req(struct sock *sk,