From: Li Zhijian <lizhijian@fujitsu.com>
To: Zhu Yanjun <zyjzyj2000@gmail.com>, Bob Pearson <rpearsonhpe@gmail.com>
Cc: jgg@ziepe.ca, leon@kernel.org, linux-rdma@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [for-next PATCH v2 1/2] RDMA/rxe: Remove unnecessary mr testing
Date: Mon, 24 Oct 2022 11:15:22 +0800 [thread overview]
Message-ID: <1dd7e09f-e22d-0c32-e084-21cac2489d10@fujitsu.com> (raw)
In-Reply-To: <CAD=hENeTnLGN5KKi_Cwni6FDb77prijHVjCjfdvhrjXdp7bdjQ@mail.gmail.com>
On 24/10/2022 10:25, Zhu Yanjun wrote:
>>>>> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
>>>>> @@ -778,6 +778,7 @@ static enum resp_states read_reply(struct rxe_qp *qp,
>>>>> if (res->state == rdatm_res_state_new) {
>>>>> if (!res->replay) {
>>>>> mr = qp->resp.mr;
>>>>> + WARN_ON(!mr);
>>>>> qp->resp.mr = NULL;
>>>>> } else {
>>>>> mr = rxe_recheck_mr(qp, res->read.rkey);
>>>>> @@ -811,8 +812,7 @@ static enum resp_states read_reply(struct rxe_qp *qp,
>>>>>
>>>>> rxe_mr_copy(mr, res->read.va, payload_addr(&ack_pkt),
>>>>> payload, RXE_FROM_MR_OBJ);
>>>>> - if (mr)
>>>>> - rxe_put(mr);
>>>>> + rxe_put(mr);
>>>>>
>>>>> if (bth_pad(&ack_pkt)) {
>>>>> u8 *pad = payload_addr(&ack_pkt) + payload
>>>>> --
>>>>> 2.31.1
>>>>>
>> Li is correct that the only way mr could be NULL is if qp->resp.mr == NULL. So the
> What I am concerned about is if "WARN_ON(!mr);" should be added or not.
> IMO, if the root cause remains unclear, this should be a problem.
> Currently this problem is not fixed. It is useless to send a debug
> statement to the maillist.
As per Bob's explanation, no 'WARN_ON(!mr)' is needed.
I will update the patch soon.
> Zhu Yanjun
>
>> 'if (mr)' is not needed if that is the case. The read_reply subroutine is reached
>> from a new rdma read operation after going through check_rkey or from a previous
>> rdma read operations from get_req if qp->resp.res != NULL or from a duplicate request
>> where the previous responder resource is found. In all these cases the mr is set.
>> Initially in check_rkey where if it can't find the mr it causes an RKEY_VIOLATION.
>> Thereafter the rkey is stored in the responder resources and looked up for each
>> packet to get an mr or cause an RKEY_VIOLATION. So the mr can't be NULL. I think
>> you can leave out the WARN and just drop the if (mr).
Very thanks for your explanation
Thanks
Zhijian
>>
>> Bob
>>
next prev parent reply other threads:[~2022-10-24 3:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-21 7:52 [for-next PATCH v2 1/2] RDMA/rxe: Remove unnecessary mr testing Li Zhijian
2022-10-21 7:52 ` Li Zhijian
2022-10-21 14:39 ` Zhu Yanjun
2022-10-22 1:09 ` Li Zhijian
2022-10-23 18:05 ` Bob Pearson
2022-10-24 2:25 ` Zhu Yanjun
2022-10-24 3:15 ` Li Zhijian [this message]
2022-10-24 14:09 ` Bob Pearson
2022-10-24 3:26 ` Li Zhijian
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