Stop tinkering with the parent's VLAN_MTU capability.

Now it is user-controlled through ifconfig(8).

The former ``automagic'' way of operation created more
trouble than good.  First, VLAN_MTU consumers other than
vlan(4) had appeared, e.g., ng_vlan(4).  Second, there was
no way to disable VLAN_MTU manually if it were causing
trouble, e.g., data corruption.

Dropping the ``automagic'' should be completely invisible
to the user since
a) all the drivers supporting VLAN_MTU
have it enabled by default, and in the first place
b) there is only one driver that can really toggle VLAN_MTU
in the hardware under its control (it's fxp(4), to which
I added VLAN_MTU controls to illustrate the principle.)

1 files changed, 7 insertions, 27 deletions

diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 55eb541..d18f056 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -651,26 +651,17 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p)
 	ifv->ifv_flags = 0;
 
 	/*
+	 * The active VLAN counter on the parent is used
+	 * at various places to see if there is a vlan(4)
+	 * attached to this physical interface.
+	 */
+	p->if_nvlans++;
+
+	/*
 	 * If the parent supports the VLAN_MTU capability,
 	 * i.e. can Tx/Rx larger than ETHER_MAX_LEN frames,
 	 * use it.
-	 * First of all, enable Tx/Rx of such extended frames on the
-	 * parent if it's disabled and we're the first to attach.
 	 */
-	p->if_nvlans++;
-	if (p->if_nvlans == 1 &&
-	    (p->if_capabilities & IFCAP_VLAN_MTU) &&
-	    (p->if_capenable & IFCAP_VLAN_MTU) == 0) {
-		struct ifreq ifr;
-		int error;
-
-		ifr.ifr_reqcap = p->if_capenable | IFCAP_VLAN_MTU;
-		error = (*p->if_ioctl)(p, SIOCSIFCAP, (caddr_t) &ifr);
-		if (error) {
-			p->if_nvlans--;
-			return (error);
-		}
-	}
 	if (p->if_capenable & IFCAP_VLAN_MTU) {
 		/*
 		 * No need to fudge the MTU since the parent can
@@ -777,17 +768,6 @@ vlan_unconfig(struct ifnet *ifp)
 		}
 
 		p->if_nvlans--;
-		if (p->if_nvlans == 0) {
-			struct ifreq ifr;
-
-			/*
-			 * Try to disable Tx/Rx of VLAN-sized frames.
-			 * This may have no effect for some interfaces,
-			 * but only the parent driver knows that.
-			 */
-			ifr.ifr_reqcap = p->if_capenable & ~IFCAP_VLAN_MTU;
-			(*p->if_ioctl)(p, SIOCSIFCAP, (caddr_t) &ifr);
-		}
 	}
 
 	/* Disconnect from parent. */