Currently, the TCP slow timer can starve TCP input processing while it

walks the list of connections in TIME_WAIT closing expired connections
due to contention on the global TCP pcbinfo lock.

To remediate, introduce a new global lock to protect the list of
connections in TIME_WAIT.  Only acquire the TCP pcbinfo lock when
closing an expired connection.  This limits the window of time when
TCP input processing is stopped to the amount of time needed to close
a single connection.

Submitted by:	Julien Charbon <jcharbon@verisign.com>
Reviewed by:	rwatson, rrs, adrian
MFC after:	2 months

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/netinet/tcp_timer.h b/sys/netinet/tcp_timer.h
index 3115fb376feb..c04723a5c97b 100644
--- a/sys/netinet/tcp_timer.h
+++ b/sys/netinet/tcp_timer.h
@@ -178,7 +178,8 @@ extern int tcp_fast_finwait2_recycle;
 void	tcp_timer_init(void);
 void	tcp_timer_2msl(void *xtp);
 struct tcptw *
-	tcp_tw_2msl_scan(int _reuse);		/* XXX temporary */
+	tcp_tw_2msl_reuse(void);	/* XXX temporary? */
+void	tcp_tw_2msl_scan(void);
 void	tcp_timer_keep(void *xtp);
 void	tcp_timer_persist(void *xtp);
 void	tcp_timer_rexmt(void *xtp);