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

lizhijian
2022-11-23T06:08:51Z

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.

>
> Do flush ops require a responder resource?

Yes, i think so. See IBA spec, oA19-9: FLUSH shall consume a single
responder...

>
> Why should CM set it unconditionally?
>

I had ever checked git history log of qp->qp_access_flags, they did as
it's. So i also think qp_access_flags should accept all new IBA
abilities unconditionally.

What do you think of this @Jason

Thanks
Zhijian
> Explain in the commit message
>
> Jason