Re: Need to set if_index in ib_init_ah_from_wc() ?

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Wed, Feb 08, 2017 at 06:02:44PM +0200, Matan Barak wrote:
 
> Actually, I think one of the problems here is that we insert GIDs
> which aren't supported by the hardware.

That certainly sounds like a problem, yes.

> So, assuming we only insert a combination of netdevices which could
> be actually described by the hardware, we could try to match these
> attributes in the gid cache table.  Once we have such a match, we
> could verify that with the ingress route (actually, we could use
> ingress route starting from get_netdev() as well).

Yes, that is the proper thing to do.

Presumably the hardware does this, it should not be receiving packets
that do not match the GID table. That would be a huge problem when we
talk about namespaces/etc.

> Since RoCE is symmetrical (you don't know if an AH is for rx/tx in
> UD and you need to select a single sgid_index for RC connections),
> we need to verify that it matches an egress route bounded to this
> netdevice.

?? how is an AH involved in RX?

> As a quick fix, setting ifindex to get_netdev's ifindex in link local
> addresses and filter out unsupported
> netdevices in the GID cache, seems like a reasonable solution to me.

That still breaks link local addresses on vlan devices, so it is an
ugly hack, not a solution.

Jason
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