Re: Question about IB_QP_CUR_STATE

[Gal Pressman <galpress@amazon.com>]

On 08/07/2020 18:44, Leon Romanovsky wrote:
> On Wed, Jul 08, 2020 at 03:42:34PM +0300, Gal Pressman wrote:
>> On 08/07/2020 12:41, liweihang wrote:
>>> Hi all,
>>>
>>> I'm a little confused about the role of IB_QP_CUR_STATE in the enumeration
>>> ib_qp_attr_mask.
>>>
>>> In manual page of ibv_modify_qp(), comments of cur_qp_state is "Assume this
>>> is the current QP state". Why we need to get current qp state from users
>>> instead of drivers?
>>>
>>> For example, why the users are allowed to modify qp from RTR to RTS again
>>> even if the qp's state in driver and hardware has already been RTS.
>>>
>>> I would be appretiate it if someone can help with this.
>>>
>>> Weihang
>>>
>>
>> Talking about IB_QP_CUR_STATE, I see many drivers filling it in their query QP
>> callback although it should only be used in modify operations.. Is there a
>> reason not to remove it?
> 
> IBTA section "11.2.5.3 QUERY QUEUE PAIR" has line about IB_QP_CUR_STATE.
> It is one of output modifiers.
> 
> Thanks
> 

It says the current QP state should be returned, that's what qp_state field is used for.
According to the man pages:

libibverbs/man/ibv_query_qp.3:
               enum ibv_qp_state       qp_state;            /* Current QP state */
               enum ibv_qp_state       cur_qp_state;        /* Current QP state - irrelevant for ibv_query_qp */