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Date:   Tue, 12 Feb 2019 10:02:12 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Chengguang Xu <cgxu519@gmx.com>
Cc:     viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH 2/2] chardev: showing minor range for chardev in the
 output of /proc/devices
Message-ID: <20190212090212.GE31657@kroah.com>
References: <20190212084739.27602-1-cgxu519@gmx.com>
 <20190212084739.27602-2-cgxu519@gmx.com>
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On Tue, Feb 12, 2019 at 04:47:39PM +0800, Chengguang Xu wrote:
> Currently chardev allows to share major, showing
> major with minor range for chardev will be more
> helpful.
> 
> Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
> ---
>  fs/char_dev.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/char_dev.c b/fs/char_dev.c
> index b25b1da097d5..6f00acdeb308 100644
> --- a/fs/char_dev.c
> +++ b/fs/char_dev.c
> @@ -55,7 +55,9 @@ void chrdev_show(struct seq_file *f, off_t offset)
>  	mutex_lock(&chrdevs_lock);
>  	for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) {
>  		if (cd->major == offset)
> -			seq_printf(f, "%3d %s\n", cd->major, cd->name);
> +			seq_printf(f, "%3d %s (%u-%u)\n", cd->major, cd->name,
> +				   cd->baseminor,
> +				   cd->baseminor + cd->minorct - 1);

You are changing the format of a userspace file, what tools are going to
break when you do this?

thanks,

greg k-h