linux-kernel - Re: [PATCH v2 3/3] crypto: hisilicon/qm - defining the device isolation strategy

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Date:   Tue, 14 Jun 2022 15:29:00 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     "yekai(A)" <yekai13@...wei.com>
Cc:     herbert@...dor.apana.org.au, linux-crypto@...r.kernel.org,
        linux-accelerators@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linuxarm@...wei.com, zhangfei.gao@...aro.org,
        wangzhou1@...ilicon.com
Subject: Re: [PATCH v2 3/3] crypto: hisilicon/qm - defining the device
 isolation strategy

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