Add a sysctl `net.link.tap.deladdrs_on_close' to configure whether tap

should delete configured addresses and routes when the interface is
closed.  Default is enabled (preserve current behaviour).

MFC after:	1 week

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/net/if_tap.c b/sys/net/if_tap.c
index 5de424ca9b45..5f6f0aaaadef 100644
--- a/sys/net/if_tap.c
+++ b/sys/net/if_tap.c
@@ -156,6 +156,7 @@ static int			tapdebug = 0;        /* debug flag   */
 static int			tapuopen = 0;        /* allow user open() */
 static int			tapuponopen = 0;    /* IFF_UP on open() */
 static int			tapdclone = 1;	/* enable devfs cloning */
+static int			tapclosedeladdrs = 1; /* del addrs on close */
 static SLIST_HEAD(, tap_softc)	taphead;             /* first device */
 static struct clonedevs 	*tapclones;
 
@@ -172,6 +173,9 @@ SYSCTL_INT(_net_link_tap, OID_AUTO, up_on_open, CTLFLAG_RW, &tapuponopen, 0,
 	"Bring interface up when /dev/tap is opened");
 SYSCTL_INT(_net_link_tap, OID_AUTO, devfs_cloning, CTLFLAG_RWTUN, &tapdclone, 0,
 	"Enably legacy devfs interface creation");
+SYSCTL_INT(_net_link_tap, OID_AUTO, deladdrs_on_close, CTLFLAG_RW,
+	&tapclosedeladdrs, 0, "Delete addresses and routes when /dev/tap is "
+	"closed");
 SYSCTL_INT(_net_link_tap, OID_AUTO, debug, CTLFLAG_RW, &tapdebug, 0, "");
 
 DEV_MODULE(if_tap, tapmodevent, NULL);
@@ -536,7 +540,8 @@ tapclose(struct cdev *dev, int foo, int bar, struct thread *td)
 	 * interface, if we are in VMnet mode. just close the device.
 	 */
 
-	if (((tp->tap_flags & TAP_VMNET) == 0) && (ifp->if_flags & IFF_UP)) {
+	if (tapclosedeladdrs == 1 && ((tp->tap_flags & TAP_VMNET) == 0) &&
+	    (ifp->if_flags & IFF_UP)) {
 		mtx_unlock(&tp->tap_mtx);
 		if_down(ifp);
 		mtx_lock(&tp->tap_mtx);