linux-kernel - Re: [PATCH v3 3/3] drivers/base/node.c: use bin

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Message-ID: <YLimj+KPaQ2P/cnl@smile.fi.intel.com>
Date:   Thu, 3 Jun 2021 12:53:19 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Tian Tao <tiantao6@...ilicon.com>
Cc:     gregkh@...uxfoundation.org, rafael@...nel.org,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        jonathan.cameron@...wei.com, song.bao.hua@...ilicon.com
Subject: Re: [PATCH v3 3/3] drivers/base/node.c: use bin_attribute to avoid
 buff overflow

On Thu, Jun 03, 2021 at 05:22:42PM +0800, Tian Tao wrote:
> Reading sys/devices/system/cpu/cpuX/nodeX/ returns cpumap and cpulist.
> However, the size of this file is limited to PAGE_SIZE because of the
> limitation for sysfs attribute. so we use bin_attribute instead of
> attribute to avoid NR_CPUS too big to cause buff overflow.

...

>  }
>  
> -static DEVICE_ATTR_RO(cpumap);
>  
> -static inline ssize_t cpulist_show(struct device *dev,
> -				   struct device_attribute *attr,
> -				   char *buf)
> +static BIN_ATTR_RO(cpumap, 0);

So, you will have 2 blank lines in a row after this. Why one is not enough?
Same question for other similar cases, if any.

-- 
With Best Regards,
Andy Shevchenko