On Sat, Aug 06, 2005 at 10:13:29PM +0200, Patrick McHardy ([EMAIL PROTECTED])
wrote:
> Evgeniy Polyakov wrote:
> >On Sat, Aug 06, 2005 at 09:37:00PM +0200, Patrick McHardy
> >([EMAIL PROTECTED]) wrote:
> >
> >>I'm working on extending netlink to work with an arbitary number
> >>of groups and stumbled over this in the w1 driver:
> >>
> >> dev->groups = 23
> >>
> >> NETLINK_CB(skb).dst_group = dev->groups;
> >> netlink_broadcast(dev->nls, skb, 0, dev->groups, GFP_ATOMIC);
> >>
> >>Apparently it wants to send to multiple groups at once, is that correct?
> >>Why does it need to do so? One limitation introduced by my patches will
> >>be that broadcasting to multiple groups won't be possible anymore and
> >>this is the only code in the kernel that uses this feature of netlink.
> >
> >
> >23 was selected arbitrary - w1 definitely can live without multicast.
>
> netlink_broadcast takes a mask of groups, 23 equal 10111, so it
> tries to broadcasts to multiple groups. I suggest to change it
> to 1.
No problem - I will create a patch.
> >According to complete removal of multicast feature - it is qiute
> >usefull, maybe it is better to make it per-socket.
> >And will not it break RTMGRP_* messages?
>
> It won't be removed, just a change in functionality. To support
> an arbitary number of groups we can't use bitmasks anymore, otherwise
> we would still be limited by the size of skb->cb. So instead of using
> masks we use group numbers. This means we can only send to a single
> group using netlink_broadcast, which is fine for all current users.
Interesting idea...
--
Evgeniy Polyakov
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