linux-kernel - Re: [PATCH] rtc/hctosys: only claim the RTC provided the system time if it did

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Message-ID: <20100208212101.GA10953@pengutronix.de>
Date:	Mon, 8 Feb 2010 22:21:01 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	rtc-linux@...glegroups.com
Cc:	Paul Gortmaker <p_gortmaker@...oo.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc/hctosys: only claim the RTC provided the system
	time if it did

Hello,

On Mon, Feb 08, 2010 at 10:10:18PM +0100, Uwe Kleine-König wrote:
> Moreover change error handling in rtc_hctosys() to use goto and so
> reduce the indention level.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
>  drivers/rtc/hctosys.c |   59 ++++++++++++++++++++++++++++--------------------
>  include/linux/rtc.h   |    6 +++++
>  2 files changed, 40 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c
> index 33c0e98..bc90b09 100644
> --- a/drivers/rtc/hctosys.c
> +++ b/drivers/rtc/hctosys.c
> @@ -22,48 +22,57 @@
>   * the best guess is to add 0.5s.
>   */
>  
> +int rtc_hctosys_ret = -ENODEV;
> +
>  static int __init rtc_hctosys(void)
>  {
> -	int err;
> +	int err = -ENODEV;
>  	struct rtc_time tm;
> +	struct timespec tv = {
> +		.tv_nsec = NSEC_PER_SEC >> 1,
> +	};
>  	struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
>  
>  	if (rtc == NULL) {
> -		printk("%s: unable to open rtc device (%s)\n",
> +		pr_err("%s: unable to open rtc device (%s)\n",
>  			__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
> -		return -ENODEV;
> +		goto err_open;
>  	}
>  
>  	err = rtc_read_time(rtc, &tm);
> -	if (err == 0) {
> -		err = rtc_valid_tm(&tm);
> -		if (err == 0) {
> -			struct timespec tv;
> +	if (err) {
> +		dev_err(rtc->dev.parent,
> +			"hctosys: unable to read the hardware clock\n");
> +		goto err_read;
>  
> -			tv.tv_nsec = NSEC_PER_SEC >> 1;
> +	}
>  
> -			rtc_tm_to_time(&tm, &tv.tv_sec);
> +	err = rtc_valid_tm(&tm);
> +	if (err) {
> +		dev_err(rtc->dev.parent,
> +			"hctosys: invalid date/time\n");
> +		goto err_invalid;
> +	}
>  
> -			do_settimeofday(&tv);
> +	rtc_tm_to_time(&tm, &tv.tv_sec);
>  
> -			dev_info(rtc->dev.parent,
> -				"setting system clock to "
> -				"%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",
> -				tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
> -				tm.tm_hour, tm.tm_min, tm.tm_sec,
> -				(unsigned int) tv.tv_sec);
> -		}
> -		else
> -			dev_err(rtc->dev.parent,
> -				"hctosys: invalid date/time\n");
> -	}
> -	else
> -		dev_err(rtc->dev.parent,
> -			"hctosys: unable to read the hardware clock\n");
> +	do_settimeofday(&tv);
>  
> +	dev_info(rtc->dev.parent,
> +		"setting system clock to "
> +		"%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",
> +		tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
> +		tm.tm_hour, tm.tm_min, tm.tm_sec,
> +		(unsigned int) tv.tv_sec);
> +
> +err_invalid:
> +err_read:
>  	rtc_class_close(rtc);
>  
> -	return 0;
> +err_open:
> +	rtc_hctosys_ret = err;
> +
> +	return err;
>  }
>  
>  late_initcall(rtc_hctosys);
> diff --git a/include/linux/rtc.h b/include/linux/rtc.h
> index 60f88a7..14dbc83 100644
> --- a/include/linux/rtc.h
> +++ b/include/linux/rtc.h
> @@ -238,6 +238,12 @@ static inline bool is_leap_year(unsigned int year)
>  	return (!(year % 4) && (year % 100)) || !(year % 400);
>  }
>  
> +#ifdef CONFIG_RTC_HCTOSYS
> +extern int rtc_hctosys_ret;
> +#else
> +#define rtc_hctosys_ret -ENODEV
> +#endif
> +
>  #endif /* __KERNEL__ */
>  
>  #endif /* _LINUX_RTC_H_ */
oops, I missed a hunk here, namely:

diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 7dd23a6..380083c 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -107,8 +107,9 @@ rtc_sysfs_show_hctosys(struct device *dev, struct device_attribute *attr,
 		char *buf)
 {
 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
-	if (strcmp(dev_name(&to_rtc_device(dev)->dev),
-		   CONFIG_RTC_HCTOSYS_DEVICE) == 0)
+	if (rtc_hctosys_ret == 0 &&
+			strcmp(dev_name(&to_rtc_device(dev)->dev),
+				CONFIG_RTC_HCTOSYS_DEVICE) == 0)
 		return sprintf(buf, "1\n");
 	else
 #endif

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
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