From 872527097680c6cf1b32ba9c5f884d29604e6659 Mon Sep 17 00:00:00 2001
From: sashan <sashan@openbsd.org>
Date: Mon, 10 Sep 2018 16:18:34 +0000
Subject: [PATCH] - if_cloners list populated at boot time only then becomes
 immutable,   so we can let go if_cloners_lock.

OK tb@, claudio@, bluhm@, kn@, henning@
---
 sys/kern/init_main.c |  8 +++++++-
 sys/net/if.c         | 34 ++++++++++------------------------
 sys/net/if_var.h     |  3 +--
 sys/sys/device.h     |  7 ++++++-
 4 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index aa4c0a83ef7..91070090bb1 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: init_main.c,v 1.280 2018/08/13 15:26:17 visa Exp $	*/
+/*	$OpenBSD: init_main.c,v 1.281 2018/09/10 16:18:34 sashan Exp $	*/
 /*	$NetBSD: init_main.c,v 1.84.4.1 1996/06/02 09:08:06 mrg Exp $	*/
 
 /*
@@ -174,6 +174,9 @@ struct emul emul_native = {
 	sigcoderet
 };
 
+#ifdef DIAGNOSTIC
+int pdevinit_done = 0;
+#endif
 
 /*
  * System startup; initialize the world, create process 0, mount root
@@ -401,6 +404,9 @@ main(void *framep)
 	for (pdev = pdevinit; pdev->pdev_attach != NULL; pdev++)
 		if (pdev->pdev_count > 0)
 			(*pdev->pdev_attach)(pdev->pdev_count);
+#ifdef DIAGNOSTIC
+	pdevinit_done = 1;
+#endif
 
 #ifdef CRYPTO
 	crypto_init();
diff --git a/sys/net/if.c b/sys/net/if.c
index f4978c1112d..0e0c767cc3b 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.c,v 1.562 2018/09/10 16:07:20 henning Exp $	*/
+/*	$OpenBSD: if.c,v 1.563 2018/09/10 16:18:34 sashan Exp $	*/
 /*	$NetBSD: if.c,v 1.35 1996/05/07 05:26:04 thorpej Exp $	*/
 
 /*
@@ -129,6 +129,8 @@
 #include <net/pfvar.h>
 #endif
 
+#include <sys/device.h>
+
 void	if_attachsetup(struct ifnet *);
 void	if_attachdomain(struct ifnet *);
 void	if_attach_common(struct ifnet *);
@@ -220,8 +222,6 @@ void	if_idxmap_remove(struct ifnet *);
 
 TAILQ_HEAD(, ifg_group) ifg_head = TAILQ_HEAD_INITIALIZER(ifg_head);
 
-/* Serialize access to &if_cloners and if_cloners_count */
-struct rwlock if_cloners_lock = RWLOCK_INITIALIZER("ifclonerslk");
 LIST_HEAD(, if_clone) if_cloners = LIST_HEAD_INITIALIZER(if_cloners);
 int if_cloners_count;
 
@@ -1253,13 +1253,11 @@ if_clone_lookup(const char *name, int *unitp)
 	if (cp - name < IFNAMSIZ-1 && *cp == '0' && cp[1] != '\0')
 		return (NULL);	/* unit number 0 padded */
 
-	rw_enter_read(&if_cloners_lock);
 	LIST_FOREACH(ifc, &if_cloners, ifc_list) {
 		if (strlen(ifc->ifc_name) == cp - name &&
 		    !strncmp(name, ifc->ifc_name, cp - name))
 			break;
 	}
-	rw_exit_read(&if_cloners_lock);
 
 	if (ifc == NULL)
 		return (NULL);
@@ -1285,22 +1283,15 @@ if_clone_lookup(const char *name, int *unitp)
 void
 if_clone_attach(struct if_clone *ifc)
 {
-	rw_enter_write(&if_cloners_lock);
+	/*
+	 * we are called at kernel boot by main(), when pseudo devices are
+	 * being attached. The main() is the only guy which may alter the
+	 * if_cloners. While system is running and main() is done with
+	 * initialization, the if_cloners becomes immutable. 
+	 */
+	KASSERT(pdevinit_done == 0);
 	LIST_INSERT_HEAD(&if_cloners, ifc, ifc_list);
 	if_cloners_count++;
-	rw_exit_write(&if_cloners_lock);
-}
-
-/*
- * Unregister a network interface cloner.
- */
-void
-if_clone_detach(struct if_clone *ifc)
-{
-	rw_enter_write(&if_cloners_lock);
-	LIST_REMOVE(ifc, ifc_list);
-	if_cloners_count--;
-	rw_exit_write(&if_cloners_lock);
 }
 
 /*
@@ -1315,17 +1306,13 @@ if_clone_list(struct if_clonereq *ifcr)
 
 	if ((dst = ifcr->ifcr_buffer) == NULL) {
 		/* Just asking how many there are. */
-		rw_enter_read(&if_cloners_lock);
 		ifcr->ifcr_total = if_cloners_count;
-		rw_exit_read(&if_cloners_lock);
 		return (0);
 	}
 
 	if (ifcr->ifcr_count < 0)
 		return (EINVAL);
 
-	rw_enter_read(&if_cloners_lock);
-
 	ifcr->ifcr_total = if_cloners_count;
 	count = MIN(if_cloners_count, ifcr->ifcr_count);
 
@@ -1341,7 +1328,6 @@ if_clone_list(struct if_clonereq *ifcr)
 		dst += IFNAMSIZ;
 	}
 
-	rw_exit_read(&if_cloners_lock);
 	return (error);
 }
 
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index e9f69c964cb..564b59037fd 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_var.h,v 1.89 2018/01/10 23:50:39 dlg Exp $	*/
+/*	$OpenBSD: if_var.h,v 1.90 2018/09/10 16:18:34 sashan Exp $	*/
 /*	$NetBSD: if.h,v 1.23 1996/05/07 02:40:27 thorpej Exp $	*/
 
 /*
@@ -328,7 +328,6 @@ void	ifafree(struct ifaddr *);
 int	if_isconnected(const struct ifnet *, unsigned int);
 
 void	if_clone_attach(struct if_clone *);
-void	if_clone_detach(struct if_clone *);
 
 int	if_clone_create(const char *, int);
 int	if_clone_destroy(const char *);
diff --git a/sys/sys/device.h b/sys/sys/device.h
index 00a1f6ad2a6..1faa0192a99 100644
--- a/sys/sys/device.h
+++ b/sys/sys/device.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: device.h,v 1.54 2015/12/11 16:07:02 mpi Exp $	*/
+/*	$OpenBSD: device.h,v 1.55 2018/09/10 16:18:34 sashan Exp $	*/
 /*	$NetBSD: device.h,v 1.15 1996/04/09 20:55:24 cgd Exp $	*/
 
 /*
@@ -164,6 +164,11 @@ struct pdevinit {
 };
 
 #ifdef _KERNEL
+
+#ifdef DIAGNOSTIC
+extern int pdevinit_done;
+#endif
+
 extern struct devicelist alldevs;	/* list of all devices */
 
 extern int autoconf_verbose;
-- 
2.20.1