Re: [PATCH v2 10/17] IB/Verbs: Adopt management helpers for IB helpers

[ira.weiny]

On Tue, Apr 07, 2015 at 03:16:30PM -0500, Steve Wise wrote:
> 
> 
> > -----Original Message-----
> > From: Jason Gunthorpe [mailto:jgunthorpe@xxxxxxxxxxxxxxxxxxxx]
> > Sent: Tuesday, April 07, 2015 3:13 PM
> > To: Michael Wang
> > Cc: Roland Dreier; Sean Hefty; linux-rdma@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-nfs@xxxxxxxxxxxxxxx;
> > netdev@xxxxxxxxxxxxxxx; Hal Rosenstock; Tom Tucker; Steve Wise; Hoang-Nam Nguyen; Christoph Raisch; Mike Marciniszyn; Eli Cohen;
> > Faisal Latif; Upinder Malhi; Trond Myklebust; J. Bruce Fields; David S. Miller; Ira Weiny; PJ Waskiewicz; Tatyana Nikolova; Or
> Gerlitz; Jack
> > Morgenstein; Haggai Eran; Ilya Nelkenbaum; Yann Droneaud; Bart Van Assche; Shachar Raindel; Sagi Grimberg; Devesh Sharma; Matan
> > Barak; Moni Shoua; Jiri Kosina; Selvin Xavier; Mitesh Ahuja; Li RongQing; Rasmus Villemoes; Alex Estrin; Doug Ledford; Eric
> Dumazet; Erez
> > Shitrit; Tom Gundersen; Chuck Lever
> > Subject: Re: [PATCH v2 10/17] IB/Verbs: Adopt management helpers for IB helpers
> > 
> > On Tue, Apr 07, 2015 at 02:35:22PM +0200, Michael Wang wrote:
> > > index f704254..4e61104 100644
> > > +++ b/drivers/infiniband/core/sa_query.c
> > > @@ -540,7 +540,7 @@ int ib_init_ah_from_path(struct ib_device *device, u8 port_num,
> > >  	ah_attr->port_num = port_num;
> > >  	ah_attr->static_rate = rec->rate;
> > >
> > > -	force_grh = rdma_port_get_link_layer(device, port_num) == IB_LINK_LAYER_ETHERNET;
> > > +	force_grh = !rdma_transport_ib(device, port_num);
> > 
> > Maybe these tests should be called cap_mandatory_grh - but I'm not
> > really sure how iWarp uses the GRH fields in the AH...
> > 
> 
> iWARP runs on top of TCP...this SA code is all IB-specific.  The reason it was checking for ETHERNET, I think, is for RoCE.    So
> this change is totally incorrect,  I think,  because RoCE is an IB transport, but it runs on ETHERNET.

But RoCE does not have an SA?

Looks like ib_init_ah_from_path was overloaded to handle non-standard "path
records".

It seems like the correct functionality would be to use ib_init_ah_from_path()
for true SA PathRecords and have another call iboe_init_ah() wrap
ib_init_ah_from_path() when RoCE address information is needed in the AH.

For Michaels patches I think 

	force_grh = rdma_device_is_iboe(...)

is the logic we need here.

Ira


> 
> Steve.
> 
> 
> 
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