Re: [PATCH] IB/core: export struct ib_port

[Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>]

 > |  > While this is true for SLtoVL, we create other files which are
 > |  > device specific under the port directory too.
 > |  > It seems like we might need to introduce a callback into the driver to
 > |  > create the port specific sysfs files.
 > | 
 > | Umm, you could have said there were other things initially!
 > 
 > Those have been there "forever" in qib without requiring the change
 > in the core sysfs code.  It's only sysfs group entries that require
 > the patch to expose ib_port.

OK, I'm confused.  Ralph originally said:

 > It [struct ib_port] is used by the new ib_qib driver to expose the SL
 > to VL table since the user level MPI library (libpsm) constructs
 > packets including the IB header.

So if that's the only use, then I'd be in favor of just exposing the
standard, generic SL-to-VL table info for all IB devices.  If there are
other per-port device-specific things, then let's give a clean way for
devices to add per-port attributes without having to know the internals
of how the RDMA core implements sysfs stuff.

 > | Anyway, rather than a callback, I guess we could just add a place to
 > | attach a set of port attributes to the structure that gets passed into
 > | ib_register_device() maybe?
 > 
 > Seems like major overkill to have callbacks, when all we need is to
 > get the structure that "owns" (is the parent kobject of) the directory.

Yes, I agree that callbacks aren't really the best way.  I was
suggesting passing in the per-port attributes as part of the ib_device
structure in ib_register_device().

 > | And maybe we could clean up the existing code that does
 > | device_create_file() to use a list of device attributes also...
 > 
 > Seems to be a rather different issue, to me.

Yes, it's independent.  But if we're passing in per-port attributes, we
might as well take the opportunity to make the API rational and pass in
per-device attributes too.

 - R.
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