Re: [for-next PATCH v6 09/10] RDMA/cm: Make QP FLUSHABLE

Jason Gunthorpe
2022-11-24T17:40:27Z

On Wed, Nov 23, 2022 at 06:07:37AM +0000, lizhijian@fujitsu.com wrote:
>
>
> On 22/11/2022 22:52, Jason Gunthorpe wrote:
> > On Wed, Nov 16, 2022 at 04:19:50PM +0800, Li Zhijian wrote:
> >> It enables flushable access flag for qp
> >>
> >> Reviewed-by: Zhu Yanjun <zyjzyj2000@gmail.com>
> >> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
> >> ---
> >> V5: new patch, inspired by Bob
> >> ---
> >> drivers/infiniband/core/cm.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> >> index 1f9938a2c475..58837aac980b 100644
> >> --- a/drivers/infiniband/core/cm.c
> >> +++ b/drivers/infiniband/core/cm.c
> >> @@ -4096,7 +4096,8 @@ static int cm_init_qp_init_attr(struct cm_id_private *cm_id_priv,
> >> qp_attr->qp_access_flags = IB_ACCESS_REMOTE_WRITE;
> >> if (cm_id_priv->responder_resources)
> >> qp_attr->qp_access_flags |= IB_ACCESS_REMOTE_READ |
> >> - IB_ACCESS_REMOTE_ATOMIC;
> >> + IB_ACCESS_REMOTE_ATOMIC |
> >> + IB_ACCESS_FLUSHABLE;
> >
> > What is the point of this? Nothing checks IB_ACCESS_FLUSHABLE ?
>
> Previous, responder of RXE will check qp_access_flags in check_op_valid():
> 256 static enum resp_states check_op_valid(struct rxe_qp *qp,
>
> 257 struct rxe_pkt_info *pkt)
>
> 258 {
>
> 259 switch (qp_type(qp)) {
>
> 260 case IB_QPT_RC:
>
> 261 if (((pkt->mask & RXE_READ_MASK) &&
>
> 262 !(qp->attr.qp_access_flags &
> IB_ACCESS_REMOTE_READ)) ||
>
>
> 263 ((pkt->mask & RXE_WRITE_MASK) &&
>
> 264 !(qp->attr.qp_access_flags &
> IB_ACCESS_REMOTE_WRITE)) ||
> 265 ((pkt->mask & RXE_ATOMIC_MASK) &&
>
> 266 !(qp->attr.qp_access_flags &
> IB_ACCESS_REMOTE_ATOMIC))) {
> 267 return RESPST_ERR_UNSUPPORTED_OPCODE;
>
> 268 }
>
> based on this, additional IB_FLUSH_PERSISTENT and IB_ACCESS_FLUSH_GLOBAL
> were added in patch7 since V5 suggested by Bob.
> Because of this change, QP should become FLUSHABLE correspondingly.

But nothing ever reads IB_ACCESS_FLUSHABLE, so why is it added?

Jason