From: Patrick McHardy <[EMAIL PROTECTED]> Date: Tue, 06 Nov 2007 01:21:09 +0100
> David Miller wrote: > > From: Patrick McHardy <[EMAIL PROTECTED]> > > Date: Mon, 05 Nov 2007 19:00:19 +0100 > > > >> This looks like a rather expensive operation for the unlikely case > >> that packets will be received by a packet socket. IMO it should only > >> be reconstructed if actually needed, by af_packet itself. > > > > Completely agreed. We should not do this by default when %99 > > of the networking stack simply does not care about this. > > > I think there is one more case that matters, which is briding > from a device with VLAN stripping for a VLAN not configured > locally. The tag will be stripped and will be lost for forwarded > packets. But I'm not exactly sure this really can be configured > (time for bed so I'll check tommorrow). If so then when such rules are loaded, just like PF_PACKET, it can set the indication to start reconstituting VLAN headers stripped by HW. > >> As we discussed some time back storing the VLAN tag in the CB on > >> TX clashes with other users of the CB like qdiscs, so we need a > >> new field in the skb for this anyway. > > > > Someone will have to find a way to remove some other fields in > > sk_buff before I'm going to allow more space to be eaten up > > by this completely fringe case feature. > > We have a two byte hole after tc_verd where we could fit this in. > But I'm pretty sure we also could reuse some other fields on input, > like queue_mapping or maybe even destructor for unowned skbs. Two bytes is enough, so if there is a hole we can use it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
