linux-kernel - Re: [PATCH] RDMA/ib_srpt: unify checking rdma_cm_id condition in srpt_cm_req

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Message-ID: <c37397fc-f406-db4a-64db-294457384c40@fujitsu.com>
Date:   Tue, 2 Aug 2022 03:35:17 +0000
From:   "lizhijian@...itsu.com" <lizhijian@...itsu.com>
To:     Bart Van Assche <bvanassche@....org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "target-devel@...r.kernel.org" <target-devel@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] RDMA/ib_srpt: unify checking rdma_cm_id condition in
 srpt_cm_req_recv()



On 02/08/2022 00:46, Bart Van Assche wrote:
> On 7/31/22 23:43, Li Zhijian wrote:
>> Although rdma_cm_id and ib_cm_id passing to srpt_cm_req_recv() are
>> exclusive currently, all other checking condition are using rdma_cm_id.
>> So unify the 'if' condition to make the code more clear.
>>
>> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
>> ---
>>   drivers/infiniband/ulp/srpt/ib_srpt.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
>> index c3036aeac89e..21cbe30d526f 100644
>> --- a/drivers/infiniband/ulp/srpt/ib_srpt.c
>> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
>> @@ -2218,13 +2218,13 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>>       ch->zw_cqe.done = srpt_zerolength_write_done;
>>       INIT_WORK(&ch->release_work, srpt_release_channel_work);
>>       ch->sport = sport;
>> -    if (ib_cm_id) {
>> -        ch->ib_cm.cm_id = ib_cm_id;
>> -        ib_cm_id->context = ch;
>> -    } else {
>> +    if (rdma_cm_id) {
>>           ch->using_rdma_cm = true;
>>           ch->rdma_cm.cm_id = rdma_cm_id;
>>           rdma_cm_id->context = ch;
>> +    } else {
>> +        ch->ib_cm.cm_id = ib_cm_id;
>> +        ib_cm_id->context = ch;
>>       }
>>       /*
>>        * ch->rq_size should be at least as large as the initiator queue
>
> Although the above patch looks fine to me, I'm not sure this kind of changes should be considered as useful or as churn?

Just want to make it more clear :). you can see below cleanup path, it's checking rdma_cm_id instead.
When i first saw these conditions, i was confused until i realized rdma_cm_id and ib_cm_id are always exclusive currently after looking into its callers

2483 free_ch:
2484         if (rdma_cm_id)
2485                 rdma_cm_id->context = NULL;
2486 else
2487                 ib_cm_id->context = NULL;
2488 kfree(ch);
2489         ch = NULL;
2490
2491         WARN_ON_ONCE(ret == 0);
2492
2493 reject:
2494         pr_info("Rejecting login with reason %#x\n", be32_to_cpu(rej->reason));
...
2499
2500         if (rdma_cm_id)
2501                 rdma_reject(rdma_cm_id, rej, sizeof(*rej),
2502 IB_CM_REJ_CONSUMER_DEFINED);
2503 else
2504                 ib_send_cm_rej(ib_cm_id, IB_CM_REJ_CONSUMER_DEFINED, NULL, 0,
2505                                rej, sizeof(*rej));

Thanks
Zhijian

>
> Bart.