linux-ext4 - Re: [PATCH 26/39] rtc/proc: switch to proc_create_single

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Date:   Thu, 19 Apr 2018 15:10:27 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Corey Minyard <minyard@....org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        linux-acpi@...r.kernel.org, drbd-dev@...ts.linbit.com,
        linux-ide@...r.kernel.org, netdev@...r.kernel.org,
        linux-rtc@...r.kernel.org, megaraidlinux.pdl@...adcom.com,
        linux-scsi@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-afs@...ts.infradead.org, linux-ext4@...r.kernel.org,
        jfs-discussion@...ts.sourceforge.net,
        netfilter-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 26/39] rtc/proc: switch to proc_create_single_data

On 19/04/2018 14:41:27+0200, Christoph Hellwig wrote:
> And stop trying to get a reference on the submodule, procfs code deals
> with release after and unloaded module and thus removed proc entry.
> 

Are you sure about that? The rtc module is not the one adding the procfs
file so I'm not sure how the procfs code can handle it.

> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  drivers/rtc/rtc-proc.c | 33 ++-------------------------------
>  1 file changed, 2 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-proc.c b/drivers/rtc/rtc-proc.c
> index 31e7e23cc5be..a9dd9218fae2 100644
> --- a/drivers/rtc/rtc-proc.c
> +++ b/drivers/rtc/rtc-proc.c
> @@ -107,40 +107,11 @@ static int rtc_proc_show(struct seq_file *seq, void *offset)
>  	return 0;
>  }
>  
> -static int rtc_proc_open(struct inode *inode, struct file *file)
> -{
> -	int ret;
> -	struct rtc_device *rtc = PDE_DATA(inode);
> -
> -	if (!try_module_get(rtc->owner))
> -		return -ENODEV;
> -
> -	ret = single_open(file, rtc_proc_show, rtc);
> -	if (ret)
> -		module_put(rtc->owner);
> -	return ret;
> -}
> -
> -static int rtc_proc_release(struct inode *inode, struct file *file)
> -{
> -	int res = single_release(inode, file);
> -	struct rtc_device *rtc = PDE_DATA(inode);
> -
> -	module_put(rtc->owner);
> -	return res;
> -}
> -
> -static const struct file_operations rtc_proc_fops = {
> -	.open		= rtc_proc_open,
> -	.read		= seq_read,
> -	.llseek		= seq_lseek,
> -	.release	= rtc_proc_release,
> -};
> -
>  void rtc_proc_add_device(struct rtc_device *rtc)
>  {
>  	if (is_rtc_hctosys(rtc))
> -		proc_create_data("driver/rtc", 0, NULL, &rtc_proc_fops, rtc);
> +		proc_create_single_data("driver/rtc", 0, NULL, rtc_proc_show,
> +				rtc);
>  }
>  
>  void rtc_proc_del_device(struct rtc_device *rtc)
> -- 
> 2.17.0
> 

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com