Re: [PATCH v3 2/2] SGE buffer and max_inline data must have same size

[Jason Gunthorpe]

On Wed, Jan 15, 2020 at 11:57:08AM -0800, Rao Shoaib wrote:
> 
> On 1/15/20 10:27 AM, Jason Gunthorpe wrote:
> > On Mon, Jan 13, 2020 at 04:41:20PM -0800, rao Shoaib wrote:
> > > From: Rao Shoaib <rao.shoaib@xxxxxxxxxx>
> > > 
> > > SGE buffer size and max_inline data should be same. Maximum of the
> > > two values requested is used.
> > > 
> > > Signed-off-by: Rao Shoaib <rao.shoaib@xxxxxxxxxx>
> > >   drivers/infiniband/sw/rxe/rxe_qp.c | 23 +++++++++++------------
> > >   1 file changed, 11 insertions(+), 12 deletions(-)
> > > 
> > > diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
> > > index aeea994..41c669c 100644
> > > +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> > > @@ -235,18 +235,17 @@ static int rxe_qp_init_req(struct rxe_dev *rxe, struct rxe_qp *qp,
> > >   		return err;
> > >   	qp->sk->sk->sk_user_data = qp;
> > > -	qp->sq.max_wr		= init->cap.max_send_wr;
> > > -	qp->sq.max_sge		= init->cap.max_send_sge;
> > > -	qp->sq.max_inline	= init->cap.max_inline_data;
> > > -
> > > -	wqe_size = max_t(int, sizeof(struct rxe_send_wqe) +
> > > -			 qp->sq.max_sge * sizeof(struct ib_sge),
> > > -			 sizeof(struct rxe_send_wqe) +
> > > -			 qp->sq.max_inline);
> > > -
> > > -	qp->sq.queue = rxe_queue_init(rxe,
> > > -				      &qp->sq.max_wr,
> > > -				      wqe_size);
> > > +	wqe_size = max_t(int, init->cap.max_send_sge * sizeof(struct ib_sge),
> > > +			 init->cap.max_inline_data);
> > > +	qp->sq.max_sge = wqe_size/sizeof(struct ib_sge);
> > > +	qp->sq.max_inline = wqe_size;
> > > +
> > > +	wqe_size += sizeof(struct rxe_send_wqe);
> > Where does this limit the user's request to RXE_MAX_WQE_SIZE ?
> 
> My understanding is that the user request can only specify sge's and/or
> inline data. The check for those is made in rxe_qp_chk_cap. Since max sge's
> and max inline data are constrained by RXE_MAX_WQE_SIZE the limit is
> enforced.

Okay, that is fine, it is a bit obtuse because of how distant
rxe_qp_chk_cap() is from this function, lets just add a comment

> > I seem to recall the if the requested max can't be satisified then
> > that is an EINVAL?
> > 
> > And the init->cap should be updated with the actual allocation.
> 
> Since the user request for both (sge's and inline data) has been satisfied I
> decided not to update the values in case the return values are being
> checked. If you prefer that I update the values I can do that.

If the sizes are increased then the driver is supposed to return the
actual maximums.

It is easy, I will fix it.

Also, your patches don't apply cleanly. You need to send patches
against the rdma for-next tree

And subjects should start with some 'RDMA/rxe: ' tag

I fixed it all and applied to for-next

Thanks,
Jason