Introduce a div_destroy() function which takes over per-vnet cleanup tasks

from the existing modevent / MOD_UNLOAD handler, and register div_destroy()
in protosw as per-vnet .pr_destroy() handler for options VIMAGE builds.  In
nooptions VIMAGE builds, div_destroy() will be invoked from the modevent
handler, resulting in effectively identical operation as it was prior this
change.  div_destroy() also tears down hashtables used by ipdivert, which
were previously left behind on ipdivert kldunloads.

For options VIMAGE builds only, temporarily disable kldunloading of ipdivert,
because without introducing additional locking logic it is impossible to
atomically check whether all ipdivert instances in all vnets are idle, and
proceed with cleanup without opening a race window for a vnet to open an
ipdivert socket while ipdivert tear-down is in progress.

While here, staticize div_init(), because it is not used outside of
ip_divert.c.

In cooperation with:	julian
Approved by:	re (rwatson), julian (mentor)
MFC after:	3 days

2 files changed, 30 insertions, 6 deletions

diff --git a/sys/netinet/ip_divert.c b/sys/netinet/ip_divert.c
index 31059e9..401c090 100644
--- a/sys/netinet/ip_divert.c
+++ b/sys/netinet/ip_divert.c
@@ -125,6 +125,8 @@ static VNET_DEFINE(struct inpcbinfo, divcbinfo);
 static u_long	div_sendspace = DIVSNDQ;	/* XXX sysctl ? */
 static u_long	div_recvspace = DIVRCVQ;	/* XXX sysctl ? */
 
+static eventhandler_tag ip_divert_event_tag;
+
 /*
  * Initialize divert connection block queue.
  */
@@ -152,7 +154,7 @@ div_inpcb_fini(void *mem, int size)
 	INP_LOCK_DESTROY(inp);
 }
 
-void
+static void
 div_init(void)
 {
 
@@ -174,8 +176,17 @@ div_init(void)
 	    NULL, NULL, div_inpcb_init, div_inpcb_fini, UMA_ALIGN_PTR,
 	    UMA_ZONE_NOFREE);
 	uma_zone_set_max(V_divcbinfo.ipi_zone, maxsockets);
-	EVENTHANDLER_REGISTER(maxsockets_change, div_zone_change,
-		NULL, EVENTHANDLER_PRI_ANY);
+}
+
+static void
+div_destroy(void)
+{
+
+	INP_INFO_LOCK_DESTROY(&V_divcbinfo);
+	uma_zdestroy(V_divcbinfo.ipi_zone);
+	hashdestroy(V_divcbinfo.ipi_hashbase, M_PCB, V_divcbinfo.ipi_hashmask);
+	hashdestroy(V_divcbinfo.ipi_porthashbase, M_PCB,
+	    V_divcbinfo.ipi_porthashmask);
 }
 
 /*
@@ -709,6 +720,9 @@ struct protosw div_protosw = {
 	.pr_ctlinput =		div_ctlinput,
 	.pr_ctloutput =		ip_ctloutput,
 	.pr_init =		div_init,
+#ifdef VIMAGE
+	.pr_destroy =		div_destroy,
+#endif
 	.pr_usrreqs =		&div_usrreqs
 };
 
@@ -716,7 +730,9 @@ static int
 div_modevent(module_t mod, int type, void *unused)
 {
 	int err = 0;
+#ifndef VIMAGE
 	int n;
+#endif
 
 	switch (type) {
 	case MOD_LOAD:
@@ -726,7 +742,11 @@ div_modevent(module_t mod, int type, void *unused)
 		 * a true IP protocol that goes over the wire.
 		 */
 		err = pf_proto_register(PF_INET, &div_protosw);
+		if (err != 0)
+			return (err);
 		ip_divert_ptr = divert_packet;
+		ip_divert_event_tag = EVENTHANDLER_REGISTER(maxsockets_change,
+		    div_zone_change, NULL, EVENTHANDLER_PRI_ANY);
 		break;
 	case MOD_QUIESCE:
 		/*
@@ -737,6 +757,10 @@ div_modevent(module_t mod, int type, void *unused)
 		err = EPERM;
 		break;
 	case MOD_UNLOAD:
+#ifdef VIMAGE
+		err = EPERM;
+		break;
+#else
 		/*
 		 * Forced unload.
 		 *
@@ -758,9 +782,10 @@ div_modevent(module_t mod, int type, void *unused)
 		ip_divert_ptr = NULL;
 		err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
 		INP_INFO_WUNLOCK(&V_divcbinfo);
-		INP_INFO_LOCK_DESTROY(&V_divcbinfo);
-		uma_zdestroy(V_divcbinfo.ipi_zone);
+		div_destroy();
+		EVENTHANDLER_DEREGISTER(maxsockets_change, ip_divert_event_tag);
 		break;
+#endif /* !VIMAGE */
 	default:
 		err = EOPNOTSUPP;
 		break;
diff --git a/sys/netinet/ip_divert.h b/sys/netinet/ip_divert.h
index 1bb0944..5036355 100644
--- a/sys/netinet/ip_divert.h
+++ b/sys/netinet/ip_divert.h
@@ -83,7 +83,6 @@ divert_find_info(struct mbuf *m)
 typedef	void ip_divert_packet_t(struct mbuf *m, int incoming);
 extern	ip_divert_packet_t *ip_divert_ptr;
 
-extern	void div_init(void);
 extern	void div_input(struct mbuf *, int);
 extern	void div_ctlinput(int, struct sockaddr *, void *);
 #endif /* _NETINET_IP_DIVERT_H_ */