Re: [PATCH v2 for-next 7/7] RDMA/hns: Add support for UD inline

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Nov 27, 2020 at 09:55:11AM +0000, liweihang wrote:
> On 2020/11/27 3:24, Jason Gunthorpe wrote:
> > On Thu, Nov 19, 2020 at 06:15:42AM +0000, liweihang wrote:
> >> On 2020/11/19 3:11, Jason Gunthorpe wrote:
> >>> On Mon, Nov 16, 2020 at 07:33:28PM +0800, Weihang Li wrote:
> >>>> @@ -503,7 +581,23 @@ static inline int set_ud_wqe(struct hns_roce_qp *qp,
> >>>>  	if (ret)
> >>>>  		return ret;
> >>>>  
> >>>> -	set_extend_sge(qp, wr, &curr_idx, valid_num_sge);
> >>>> +	if (wr->send_flags & IB_SEND_INLINE) {
> >>>> +		ret = set_ud_inl(qp, wr, ud_sq_wqe, &curr_idx);
> >>>> +		if (ret)
> >>>> +			return ret;
> >>>
> >>> Why are you implementing this in the kernel? No kernel ULP sets this
> >>> flag?
> >>
> >> Sorry, I don't understand. Some kernel users may set IB_SEND_INLINE
> >> when using UD, some may not, we just check this flag to decide how
> >> to fill the data into UD SQ WQE here.
> > 
> > I mean if you 'git grep IB_SEND_INLINE' nothing uses it. 
> > 
> > This is all dead code.
> > 
> > How did you test it?
> > 
> > Jason
> > 
> 
> Hi Jason,
> 
> We have tested it with our own tools. After running 'git grep IB_SEND_INLINE',
> I found following drivers refer to this flag:
> 
> bnxt_re/cxgb4/i40iw/mlx5/ocrdma/qedr/rxe/siw
> 
> So I'm still a bit confused. Do you mean that no kernel ULP uses UD inline or
> the IB_SEND_INLINE flag? 

Yes

> Should current related codes be removed?

Quite possibly, though rxe and siw might be using it as part of the
uAPI

> I also found a very old discussion about removing this flag, but there was no
> futher information:
> 
> https://lists.openfabrics.org/pipermail/general/2007-August/039826.html

Right, it has been unused for a very long time, I doubt it will ever
get used

Jason