svn commit: r312907 - head/sys/netinet

[Hiren Panchasara]

Author: hiren
Date: Fri Jan 27 23:10:46 2017
New Revision: 312907
URL: https://svnweb.freebsd.org/changeset/base/312907

Log:
  Add a knob to change default behavior of inheriting listen socket's tcp stack
  regardless of what the default stack for the system is set to.
  
  With current/default behavior, after changing the default tcp stack, the
  application needs to be restarted to pick up that change. Setting this new knob
  net.inet.tcp.functions_inherit_listen_socket_stack to '0' would change that
  behavior and make any new connection use the newly selected default tcp stack.
  
  Reviewed by:		rrs
  MFC after:		2 weeks
  Sponsored by:		Limelight Networks

Modified:
  head/sys/netinet/tcp_syncache.c

Modified: head/sys/netinet/tcp_syncache.c
==============================================================================
--- head/sys/netinet/tcp_syncache.c	Fri Jan 27 23:08:30 2017	(r312906)
+++ head/sys/netinet/tcp_syncache.c	Fri Jan 27 23:10:46 2017	(r312907)
@@ -120,6 +120,14 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, sync
     &VNET_NAME(tcp_syncookiesonly), 0,
     "Use only TCP SYN cookies");
 
+static VNET_DEFINE(int, functions_inherit_listen_socket_stack) = 1;
+#define V_functions_inherit_listen_socket_stack \
+    VNET(functions_inherit_listen_socket_stack)
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, functions_inherit_listen_socket_stack,
+    CTLFLAG_VNET | CTLFLAG_RW,
+    &VNET_NAME(functions_inherit_listen_socket_stack), 0,
+    "Inherit listen socket's stack");
+
 #ifdef TCP_OFFLOAD
 #define ADDED_BY_TOE(sc) ((sc)->sc_tod != NULL)
 #endif
@@ -830,7 +838,7 @@ syncache_socket(struct syncache *sc, str
 	tcp_rcvseqinit(tp);
 	tcp_sendseqinit(tp);
 	blk = sototcpcb(lso)->t_fb;
-	if (blk != tp->t_fb) {
+	if (V_functions_inherit_listen_socket_stack && blk != tp->t_fb) {
 		/*
 		 * Our parents t_fb was not the default,
 		 * we need to release our ref on tp->t_fb and