[src/trunk]: src/sys/net Resequence the stuff in tundetach() to ensure that n...

[pgoyette <pgoyette%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5086fe7bff4c
branches:  trunk
changeset: 449821:5086fe7bff4c
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Mon Mar 25 09:07:24 2019 +0000

description:
Resequence the stuff in tundetach() to ensure that no new device units
can be created by either 'ifconfig create' or 'open("/dev/tun0")' paths.

Note: previous efforts at fixing 'modunload if_tun' are abandoned, since
there is no bug.  Just need to ensure that the cloned interface is both
close(1)d _and_ 'ifconfig tunx destroy' before trying to unload.

diffstat:

 sys/net/if_tun.c |  31 +++++++++++++++++++------------
 1 files changed, 19 insertions(+), 12 deletions(-)

diffs (55 lines):

diff -r 000a151421e2 -r 5086fe7bff4c sys/net/if_tun.c
--- a/sys/net/if_tun.c  Mon Mar 25 07:34:13 2019 +0000
+++ b/sys/net/if_tun.c  Mon Mar 25 09:07:24 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_tun.c,v 1.153 2019/03/25 04:06:36 msaitoh Exp $     */
+/*     $NetBSD: if_tun.c,v 1.154 2019/03/25 09:07:24 pgoyette Exp $    */
 
 /*
  * Copyright (c) 1988, Julian Onions <jpo%cs.nott.ac.uk@localhost>
@@ -19,7 +19,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_tun.c,v 1.153 2019/03/25 04:06:36 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_tun.c,v 1.154 2019/03/25 09:07:24 pgoyette Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -144,19 +144,26 @@
 {
        int error = 0;
 
-       if (!LIST_EMPTY(&tun_softc_list) || !LIST_EMPTY(&tunz_softc_list))
-               error = EBUSY;
-
+       if_clone_detach(&tun_cloner);
 #ifdef _MODULE
-       if (error == 0)
-               error = devsw_detach(NULL, &tun_cdevsw);
+       error = devsw_detach(NULL, &tun_cdevsw);
+       if (error != 0) {
+               if_clone_attach(&tun_cloner);
+               return error;
+       }
 #endif
-       if (error == 0) {
-               if_clone_detach(&tun_cloner);
-               mutex_destroy(&tun_softc_lock);
-       }
 
-       return error;
+       if (!LIST_EMPTY(&tun_softc_list) || !LIST_EMPTY(&tunz_softc_list)) {
+#ifdef _MODULE
+               devsw_attach("tun", NULL, &tun_bmajor, &tun_cdevsw, &tun_cmajor);
+#endif
+               if_clone_attach(&tun_cloner);
+               return EBUSY;
+}
+
+       mutex_destroy(&tun_softc_lock);
+
+       return 0;
 }
 
 /*