Re: [PATCH for-rc] RDMA/srpt: Fix disabling device management

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, May 13, 2020 at 08:25:41AM -0700, Bart Van Assche wrote:
> On 2020-05-13 05:43, Jason Gunthorpe wrote:
> > On Wed, May 13, 2020 at 03:38:37PM +0300, Kamal Heib wrote:
> >>>> Correct me if I'm wrong, Do you mean check the return value from
> >>>> rdma_cap_ib_mad()?
> >>>
> >>> I think so.
> >>>
> >>> Thanks
> >>
> >> Well, this function will not help in the case of VFs, because the flag
> >> that is checked in rdma_cap_ib_mad() is RDMA_CORE_CAP_IB_MAD which is
> >> set almost for each create IB device as part of RDMA_CORE_PORT_IBA_IB or
> >> RDMA_CORE_PORT_IBA_ROCE or RDMA_CORE_PORT_IBA_ROCE_UDP_ENCAP.
> > 
> > AFAIK this case only happens for mlx4 devices that use the GUID table
> > to emulate virtual IB ports. In this case there is no bit to control.
> > 
> > I didn't quite understand why srpt has this stuff, does it mean it is
> > broken on mlx4 vports? Why allow the failure?
> 
> The commit message of the code that introduced the most recent
> IB_PORT_DEVICE_MGMT_SUP changes is as follows:
> 
> commit 09f8a1486dcaf69753961a6df6cffdaafc5ccbcb
> Author: Bart Van Assche <bvanassche@acm.org>
> Date:   Mon Sep 30 16:17:01 2019 -0700
> 
> RDMA/srpt: Fix handling of SR-IOV and iWARP ports
> 
> Management datagrams (MADs) are not supported by SR-IOV VFs nor by iWARP
> ports. Support SR-IOV VFs and iWARP ports by only logging an error
> message if MAD handler registration fails.
> 
> In other words, on my setup the ib_srpt driver was working find with SR-IOV.

But it won't be properly discoverable without the
IB_PORT_DEVICE_MGMT_SUP flag being set on the physical port?

Jason