Re: [PATCH v2 07/11] IB/cm: Add network namespace support

["ira.weiny" <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Mon, Apr 20, 2015 at 11:06:59AM -0600, Jason Gunthorpe wrote:
> On Mon, Apr 20, 2015 at 12:03:38PM +0300, Haggai Eran wrote:
> > From: Guy Shapiro <guysh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > 
> > Add namespace support to the IB-CM layer.
> 
> > - Each CM-ID now has a network namespace it is associated with, assigned at
> >   creation. This namespace is used as needed during subsequent action on the
> >   CM-ID or related objects.
> 
> There is really something weird about this layering. At the CM layer
> there should be no concept of an IP address, it only deals with GIDs.
> 
> So how can a CM object have a network namespace associated with it?
> 
> >  {
> >  	av->port = port;
> >  	av->pkey_index = wc->pkey_index;
> >  	ib_init_ah_from_wc(port->cm_dev->ib_device, port->port_num, wc,
> > -			   grh, &av->ah_attr, &init_net);
> > +			   grh, &av->ah_attr, net);
> 
> There is something deeply wrong with adding network namespace
> arguments to verbs.
> 
> For rocee the gid index clearly specifies the network namespace
> to use, so much of this should go away and have rocee get the
> namespace from the gid index.
> 
> Ie in ib_init_ah_from_wc we have the ib_wc which contains the sgid
> index.
> 
> I'm really not excited at how many places are gaining a net when those
> layers shouldn't even need to care about IP layer details. Just acting
> as a pass through for rocee doesn't make sense.
> 

I had the same feeling when I saw the addition of the network namespace to the
MAD code, especially the RMPP code.

It seems like there should be a better way to deal with this.  My gut says that
the namespace should be handled separate from the ib_init_ah_from_wc.  Perhaps
as a secondary call used only when the namespace is needed?  But I'm not sure
when it is appropriate/needed.

Ira

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