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Subject: Re: [PATCH v2 3/3] crypto: hisilicon/qm - defining the device
 isolation strategy
To:     Greg KH <gregkh@linuxfoundation.org>
References: <20220614122943.1406-1-yekai13@huawei.com>
 <20220614122943.1406-4-yekai13@huawei.com> <YqiCaTAaRoq7c0y0@kroah.com>
 <b597023a-5569-f4be-1e30-78d0d961dfdc@huawei.com>
 <YqiNHOfXHRtaQyZV@kroah.com>
CC:     <herbert@gondor.apana.org.au>, <linux-crypto@vger.kernel.org>,
        <linux-accelerators@lists.ozlabs.org>,
        <linux-kernel@vger.kernel.org>, <linuxarm@huawei.com>,
        <zhangfei.gao@linaro.org>, <wangzhou1@hisilicon.com>
From:   "yekai(A)" <yekai13@huawei.com>
Message-ID: <ed292f66-fcec-3803-4f29-b94e60ee913e@huawei.com>
Date:   Wed, 15 Jun 2022 17:10:48 +0800
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On 2022/6/14 21:29, Greg KH wrote:
> On Tue, Jun 14, 2022 at 09:24:08PM +0800, yekai(A) wrote:
>>>>  struct hisi_qm {
>>>>  	enum qm_hw_ver ver;
>>>>  	enum qm_fun_type fun_type;
>>>> @@ -335,6 +341,9 @@ struct hisi_qm {
>>>>  	struct qm_shaper_factor *factor;
>>>>  	u32 mb_qos;
>>>>  	u32 type_rate;
>>>> +	struct list_head uacce_hw_errs;
>>>> +	atomic_t uacce_ref; /* reference of the uacce */
>>>
>>> That is not how reference counts work, sorry.  Please use 'struct kref'
>>> for a real reference count, never roll your own.
>>>
>>> thanks,
>>>
>>> greg k-h
>>> .
>>>
>>
>> this atomic_t reference is lightweight than 'struct kref',
>
> It's the same size, why would it be "lighter"?  Why do you need it to be
> lighter, what performance issue is there with a kref?
>
>> this reference
>> means whether the task is running. So would it be better to use atomic_t
>> reference?
>
> I do not know, as "running or not running" is a state, not a count or a
> reference.  why does this have to be atomic at all?
>
> thanks,
>
> greg k-h
> .
>

I will use 'qm_state' instead of reference count by zhangfei Gao's opinion.

Thanks
Kai