Re: [PATCH v5 19/27] IB/Verbs: Use management helper cap_iw_cm()

[Tom Tucker]

On 4/20/15 11:19 AM, Jason Gunthorpe wrote:
> On Mon, Apr 20, 2015 at 10:51:58AM -0500, Tom Tucker wrote:
> > On 4/20/15 10:16 AM, Michael Wang wrote:
> > > On 04/20/2015 04:00 PM, Steve Wise wrote:
> > > > On 4/20/2015 3:40 AM, Michael Wang wrote:
> > > [snip]
> > > > > diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> > > > > index 6805e3e..e4999f6 100644
> > > > > +++ b/include/rdma/ib_verbs.h
> > > > > @@ -1818,6 +1818,21 @@ static inline int cap_ib_cm(struct ib_device *device, u8 port_num)
> > > > >        return rdma_ib_or_iboe(device, port_num);
> > > > >    }
> > > > >    +/**
> > > > > + * cap_iw_cm - Check if the port of device has the capability IWARP
> > > > > + * Communication Manager.
> > > > > + *
> > > > > + * @device: Device to be checked
> > > > > + * @port_num: Port number of the device
> > > > > + *
> > > > > + * Return 0 when port of the device don't support IWARP
> > > > > + * Communication Manager.
> > > > > + */
> > > > > +static inline int cap_iw_cm(struct ib_device *device, u8 port_num)
> > > > > +{
> > > > > +    return rdma_tech_iwarp(device, port_num);
> > > > > +}
> > > > > +
> > > > >    int ib_query_gid(struct ib_device *device,
> > > > >             u8 port_num, int index, union ib_gid *gid);
> > > > iWARP devices _must_ support the IWCM so cap_iw_cm() is not really useful.
> > > Sean suggested to add this helper paired with cap_ib_cm(), may be there are
> > > some consideration on maintainability?
> > >
> > > Me too also prefer this way to make the code more readable ;-)
> > It's more consistent, but not necessarily more readable -- if by
> > readability we mean understanding.
> >
> > If the reader knows how the transports work, then the reader would
> > be confused by the addition of a check that is always true. For the
> > reader that doesn't know, the addition of the check implies that the
> > support is optional, which it is not.
> No, it says this code is concerned with the unique parts of iWarp
> related to CM, not the other unique parts of iWarp. The check isn't
> aways true, it is just always true on iWarp devices.
>
> That became the problem with the old way of just saying 'is iWarp'
> (and others). There are too many differences, the why became lost in
> many places.
>
> There are now too many standards, and several do not have public docs,
> to keep relying on a mess of 'is standard' tests.

You're right Jason, this gets called with the device handle so it's only 
true for iwarp.

> Jason
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