On 18/05/2022 11:41, Bob Pearson wrote:
>
>
> -------- Forwarded Message --------
> Subject: Re: Bug in pyverbs for test_qp_ex_rc_bind_mw
> Date: Tue, 17 May 2022 22:41:08 -0500
> From: Bob Pearson <rpearsonhpe@xxxxxxxxx>
> To: Jason Gunthorpe <jgg@xxxxxxxxxx>, Zhu Yanjun <zyjzyj2000@xxxxxxxxx>, Edward Srouji <edwards@xxxxxxxxxx>, Leon Romanovsky <leon@xxxxxxxxxx>
>
> On 5/17/22 21:57, Bob Pearson wrote:
>> test_qp_ex_rc_bind_mw has an error in that the new_rkey is computed from the old mr rkey and not the old mw rkey.
>> The following lines
>>
>> mw = MW(server.pd, mw_type=e.IBV_MW_TYPE_2)
>> ...
>> new_rkey = inc_rkey(server.mr.rkey)
>> server.qp.wr_bind_mw(mw, new_rkey, bind_info)
>>
>> will compute a new rkey with the same index as mr and a key portion that is one larger than mr modulo 256.
>> This is passed to wr_bind_mw which expects a parameter with a new key portion of the mw (not the mr).
>> The memory windows implementation in rxe generates a random initial rkey for mw and for bind_mw it
>> checks that the new 8 bit key is different than the old key. Since the mr and mw are random wrt each other
>> we expect that the new key will match the old key approx 1 out of 256 test runs which will cause an error
>> which is just what I see.
>>
>> The correct code should be
>>
>> new_key = inc_rkey(<old mw.rkey>)
>>
>> which will guarantee that it is always different than the previous key. The problem is I can't figure out
>> how to compute the rkey from the mw or I would submit a patch.
>>
>> Bob
>>
> If in test_qpex.py I type
>
> print("mw = ", mw)
> print("mr = ", self.server.mr)
>
> I get
>
> mw = MW:
> Rkey : 12345678
> Handle : 4
> MW Type : IBV_MW_TYPE_2
>
> mr = MR
> lkey : 432134
> rkey : 432134
> length : 1024
> buf : 9403912345678
> handle : 2
>
> The difference is the colon ':' after MW and caps.
For the difference, just post a RP to make them identical: https://github.com/linux-rdma/rdma-core/pull/1175
Thanks
Zhijian
>
> I can refer to mr.rkey as self.server.mr.rkey no problem
>
> but mw.Rkey doesn't work. Neither does mw.rkey or anything else I have thought of.
>
> I hate python. Just hate it.
>
> Bob
