linux-kernel - Re: [PATCH v4 1/5] rtc: sysfs: facilitate attribute add to rtc device

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Message-ID: <1531899467.6017.9.camel@diehl.com>
Date:   Wed, 18 Jul 2018 07:37:47 +0000
From:   Denis OSTERLAND <denis.osterland@...hl.com>
To:     "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "m.grzeschik@...gutronix.de" <m.grzeschik@...gutronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH v4 1/5] rtc: sysfs: facilitate attribute add to rtc device

Hello,

thanks for your comments.

Am Mittwoch, den 18.07.2018, 09:25 +0200 schrieb Alexandre Belloni:
> Hello,
> 
> On 10/07/2018 09:44:15+0000, Denis OSTERLAND wrote:
> > 
> > +
> > +static size_t rtc_group_count(struct rtc_device *rtc)
> > +{
> I don't feel this function is necessary, you can include it in __rtc_add_group
I think that it is easier to read, but sure I can include it.
> 
> > 
> > +
> > +static inline int
> > +__rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
> > +{
> > +	size_t cnt = rtc_group_count(rtc);
> > +	const struct attribute_group **groups, **old;
> > +
> > +	groups = devm_kzalloc(&rtc->dev, (cnt+2)*sizeof(*groups), GFP_KERNEL);
> Please use devm_kcalloc
okay
> 
> > 
> > +	if (IS_ERR_OR_NULL(groups))
> > +		return PTR_ERR(groups);
> > +	memcpy(groups, rtc->dev.groups, cnt*sizeof(*groups));
> > +	groups[cnt] = grp;
> > +
> > +	old = rtc->dev.groups;
> > +	rtc->dev.groups = groups;
> > +	if (old != rtc_attr_groups)
> > +		devm_kfree(&rtc->dev, old);
> > +
> > +	return 0;
> > +}
> > +
> > +int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
> > +{
> > +	return rtc->dev.kobj.state_in_sysfs ?
> > +		devm_device_add_group(&rtc->dev, grp) :
> > +		__rtc_add_group(rtc, grp);
> Using devm_device_add_group after RTC registration is racy and should
> not be allowed. I would merge __rtc_add_group in rtc_add_group and
> return an error if rtc->registered is true.
You are right. An error in this case is better.
> 
> 

Regards Denis

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