[openib-general] zero-sized memory regions

[Roland Dreier]

    Michael> Hi!  Currently an attempt to create a zero sized memory
    Michael> region in mthca succeeds, but apparently the key field in
    Michael> the region returned is uninitialized.  Further,
    Michael> buffer_list passed in must have length of at least 1
    Michael> which is somewhat counterintuitive.

    Michael> Should not the operation rather return -EINVAL, and avoid
    Michael> accessing the buffer list at all?  Roland - want a patch
    Michael> like this?

>From looking at the IB spec, it seems that a length of 0 is valid.
However I agree that the current behavior is not reasonable, and I
don't particularly feel like implementing 0 length regions.  So
returning -EINVAL before we do anything is probably the best way to
go.

 - R.