kern/57100: disable hardware checksums when using bridge(4).

[Bruce M Simpson]

Here is a somewhat improved patch for tweaking the behaviour of the bridge
code with respect to disabling the hardware-assist-checksum features of
driver instances which are members of the bridge.

I don't make use of the bridge code so I'd appreciate it if others who do
could test this patch.

To disable *all* capabilities, setting net.link.ether.bridge.hwassmask to
0 should suffice.

Regards,
BMS
-------------- next part --------------
This patch implements a sysctl MIB variable, net.link.ether.bridge.hwassmask,
which may be used to specify a bitmask which is applied to each member
interface of a bridge to selectively disable interface hardware assist
capabilities, and provides finer run-time control over such behaviour.

Index: bridge.c
===================================================================
RCS file: /home/ncvs/src/sys/net/bridge.c,v
retrieving revision 1.79
diff -u -p -r1.79 bridge.c
--- bridge.c	15 Jun 2004 23:57:41 -0000	1.79
+++ bridge.c	3 Jul 2004 17:33:47 -0000
@@ -204,6 +204,10 @@ SYSCTL_NODE(_net_link_ether, OID_AUTO, b
 static char bridge_version[] = "031224";
 SYSCTL_STRING(_net_link_ether_bridge, OID_AUTO, version, CTLFLAG_RD,
 	bridge_version, 0, "software version");
+static u_long bridge_hwassmask = 0xFFFFFFFFUL;
+SYSCTL_ULONG(_net_link_ether_bridge, OID_AUTO, hwassmask, CTLFLAG_RW,
+	&bridge_hwassmask, 0,
+	"Mask to apply to if_hwassist field for bridge interfaces");
 
 #define BRIDGE_DEBUG
 #ifdef BRIDGE_DEBUG
@@ -391,6 +395,7 @@ bridge_off(void)
 
 	if ( b->flags & IFF_BDG_PROMISC ) {
 	    ifpromisc(ifp, 0);
+	    ifp->if_hwassist = b->hwassist;
 	    b->flags &= ~(IFF_BDG_PROMISC|IFF_MUTE) ;
 	    DPRINTF(("%s: %s promisc OFF if_flags 0x%x "
 		"bdg_flags 0x%x\n", __func__, ifp->if_xname,
@@ -433,6 +438,8 @@ bridge_on(void)
 	    if_up(ifp);
 	}
 	if ( !(b->flags & IFF_BDG_PROMISC) ) {
+	    b->hwassist = ifp->if_hwassist;
+	    ifp->if_hwassist &= bridge_hwassmask;
 	    (void) ifpromisc(ifp, 1);
 	    b->flags |= IFF_BDG_PROMISC ;
 	    DPRINTF(("%s: %s promisc ON if_flags 0x%x bdg_flags 0x%x\n",
Index: bridge.h
===================================================================
RCS file: /home/ncvs/src/sys/net/bridge.h,v
retrieving revision 1.12
diff -u -p -r1.12 bridge.h
--- bridge.h	15 Nov 2002 00:00:14 -0000	1.12
+++ bridge.h	3 Jul 2004 17:26:44 -0000
@@ -48,6 +48,7 @@ struct bdg_softc {
 #define IFF_MUTE        0x0002  /* mute this if for bridging.   */
 #define IFF_USED        0x0004  /* use this if for bridging.    */
     struct cluster_softc *cluster;
+    u_long hwassist;		/* saved ifp->if_hwassist field */
 } ;
 
 extern struct bdg_softc *ifp2sc;