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Subject: Re: [PATCH RFC 01/12] RDMA/rtrs-srv: Remove ib_dev_count from
 rtrs_srv_ib_ctx
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To:     Jinpu Wang <jinpu.wang@ionos.com>
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From:   Guoqing Jiang <guoqing.jiang@linux.dev>
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Date:   Mon, 14 Nov 2022 16:00:55 +0800
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Hi Jinpu,

On 11/14/22 3:39 PM, Jinpu Wang wrote:
> Hi Guoqing,
>
> Thx for the patch, see comments below.
> On Sun, Nov 13, 2022 at 2:08 AM Guoqing Jiang <guoqing.jiang@linux.dev> wrote:
>> The ib_dev_count is supposed to track the number of added ib devices
>> which is only used in rtrs_srv_{add,remove}_one.
>>
>> However we only trigger rtrs_srv_add_one from rnbd_srv_init_module
>> -> rtrs_srv_open -> ib_register_client -> client->add which should
>> happen only once.
> client->add is call per ib_device, eg:
> jwang@ps404a-1.stg:~$ ls -l /sys/class/infiniband/mlx5_*
> lrwxrwxrwx 1 root root 0 Nov  8 13:49 /sys/class/infiniband/mlx5_0 ->
> ../../devices/pci0000:ae/0000:ae:00.0/0000:af:00.0/infiniband/mlx5_0
> lrwxrwxrwx 1 root root 0 Nov  8 13:49 /sys/class/infiniband/mlx5_1 ->
> ../../devices/pci0000:ae/0000:ae:00.0/0000:af:00.1/infiniband/mlx5_1
> rtrs will be call twice for  mlx5_0 and mlx5_1 devices

Ah, yes.

But still we can only load/unload module once, I guess it was used to avoid
racy condition (concurrent loading/unloading module?), could you elaborate
why it is needed?

Thanks,
Guoqing