Commit 4396e461 authored by Soheil Hassas Yeganeh's avatar Soheil Hassas Yeganeh Committed by David S. Miller
Browse files

tcp: remove tcp_tw_recycle 



The tcp_tw_recycle was already broken for connections
behind NAT, since the per-destination timestamp is not
monotonically increasing for multiple machines behind
a single destination address.

After the randomization of TCP timestamp offsets
in commit 8a5bd45f6616 (tcp: randomize tcp timestamp offsets
for each connection), the tcp_tw_recycle is broken for all
types of connections for the same reason: the timestamps
received from a single machine is not monotonically increasing,
anymore.

Remove tcp_tw_recycle, since it is not functional. Also, remove
the PAWSPassive SNMP counter since it is only used for
tcp_tw_recycle, and simplify tcp_v4_route_req and tcp_v6_route_req
since the strict argument is only set when tcp_tw_recycle is
enabled.

Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Cc: Lutz Vieweg <lvml@5t9.de>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d82bae12

Documentation/networking/ip-sysctl.txt

+0 −5
Original line number Diff line number Diff line
@@ -640,11 +640,6 @@ tcp_tso_win_divisor - INTEGER 
	building larger TSO frames.

	Default: 3



tcp_tw_recycle - BOOLEAN

	Enable fast recycling TIME-WAIT sockets. Default value is 0.

	It should not be changed without advice/request of technical

	experts.



tcp_tw_reuse - BOOLEAN

	Allow to reuse TIME-WAIT sockets for new connections when it is

	safe from protocol viewpoint. Default value is 0.

include/net/netns/ipv4.h

+0 −1
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ struct inet_timewait_death_row { 
	atomic_t		tw_count;



	struct inet_hashinfo 	*hashinfo ____cacheline_aligned_in_smp;

	int			sysctl_tw_recycle;

	int			sysctl_max_tw_buckets;

};

include/net/tcp.h

+1 −2
Original line number Diff line number Diff line
@@ -1810,8 +1810,7 @@ struct tcp_request_sock_ops { 
				 __u16 *mss);

#endif

	struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,

				       const struct request_sock *req,

				       bool *strict);

				       const struct request_sock *req);

	__u32 (*init_seq_tsoff)(const struct sk_buff *skb, u32 *tsoff);

	int (*send_synack)(const struct sock *sk, struct dst_entry *dst,

			   struct flowi *fl, struct request_sock *req,

include/uapi/linux/snmp.h

+0 −1
Original line number Diff line number Diff line
@@ -177,7 +177,6 @@ enum 
	LINUX_MIB_TIMEWAITED,			/* TimeWaited */

	LINUX_MIB_TIMEWAITRECYCLED,		/* TimeWaitRecycled */

	LINUX_MIB_TIMEWAITKILLED,		/* TimeWaitKilled */

	LINUX_MIB_PAWSPASSIVEREJECTED,		/* PAWSPassiveRejected */

	LINUX_MIB_PAWSACTIVEREJECTED,		/* PAWSActiveRejected */

	LINUX_MIB_PAWSESTABREJECTED,		/* PAWSEstabRejected */

	LINUX_MIB_DELAYEDACKS,			/* DelayedACKs */

net/ipv4/proc.c

+0 −1
Original line number Diff line number Diff line
@@ -199,7 +199,6 @@ static const struct snmp_mib snmp4_net_list[] = { 
	SNMP_MIB_ITEM("TW", LINUX_MIB_TIMEWAITED),

	SNMP_MIB_ITEM("TWRecycled", LINUX_MIB_TIMEWAITRECYCLED),

	SNMP_MIB_ITEM("TWKilled", LINUX_MIB_TIMEWAITKILLED),

	SNMP_MIB_ITEM("PAWSPassive", LINUX_MIB_PAWSPASSIVEREJECTED),

	SNMP_MIB_ITEM("PAWSActive", LINUX_MIB_PAWSACTIVEREJECTED),

	SNMP_MIB_ITEM("PAWSEstab", LINUX_MIB_PAWSESTABREJECTED),

	SNMP_MIB_ITEM("DelayedACKs", LINUX_MIB_DELAYEDACKS),

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