[PATCH v1 1/1] rtc: sysfs: Use sysfs_emit() to instead of s*printf()

[PATCH v1 1/1] rtc: sysfs: Use sysfs_emit() to instead of s*printf()

[Andy Shevchenko]

Follow the advice of the Documentation/filesystems/sysfs.rst that show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the value
to be returned to user space.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/rtc/sysfs.c | 46 +++++++++++++++++++++------------------------
 1 file changed, 21 insertions(+), 25 deletions(-)

diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c
index e3062c4d3f2c..86d1140b4f39 100644
--- a/drivers/rtc/sysfs.c
+++ b/drivers/rtc/sysfs.c
@@ -24,8 +24,8 @@
 static ssize_t
 name_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
-		       dev_name(dev->parent));
+	return sysfs_emit(buf, "%s %s\n", dev_driver_string(dev->parent),
+			  dev_name(dev->parent));
 }
 static DEVICE_ATTR_RO(name);
 
@@ -39,7 +39,7 @@ date_show(struct device *dev, struct device_attribute *attr, char *buf)
 	if (retval)
 		return retval;
 
-	return sprintf(buf, "%ptRd\n", &tm);
+	return sysfs_emit(buf, "%ptRd\n", &tm);
 }
 static DEVICE_ATTR_RO(date);
 
@@ -53,7 +53,7 @@ time_show(struct device *dev, struct device_attribute *attr, char *buf)
 	if (retval)
 		return retval;
 
-	return sprintf(buf, "%ptRt\n", &tm);
+	return sysfs_emit(buf, "%ptRt\n", &tm);
 }
 static DEVICE_ATTR_RO(time);
 
@@ -64,21 +64,17 @@ since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
 	struct rtc_time tm;
 
 	retval = rtc_read_time(to_rtc_device(dev), &tm);
-	if (retval == 0) {
-		time64_t time;
+	if (retval)
+		return retval;
 
-		time = rtc_tm_to_time64(&tm);
-		retval = sprintf(buf, "%lld\n", time);
-	}
-
-	return retval;
+	return sysfs_emit(buf, "%lld\n", rtc_tm_to_time64(&tm));
 }
 static DEVICE_ATTR_RO(since_epoch);
 
 static ssize_t
 max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
+	return sysfs_emit(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
 }
 
 static ssize_t
@@ -118,9 +114,9 @@ hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
 	if (rtc_hctosys_ret == 0 &&
 	    strcmp(dev_name(&to_rtc_device(dev)->dev),
 		   CONFIG_RTC_HCTOSYS_DEVICE) == 0)
-		return sprintf(buf, "1\n");
+		return sysfs_emit(buf, "1\n");
 #endif
-	return sprintf(buf, "0\n");
+	return sysfs_emit(buf, "0\n");
 }
 static DEVICE_ATTR_RO(hctosys);
 
@@ -128,7 +124,6 @@ static ssize_t
 wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	ssize_t retval;
-	time64_t alarm;
 	struct rtc_wkalrm alm;
 
 	/* Don't show disabled alarms.  For uniformity, RTC alarms are
@@ -140,12 +135,13 @@ wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
 	 * alarms after they trigger, to ensure one-shot semantics.
 	 */
 	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
-	if (retval == 0 && alm.enabled) {
-		alarm = rtc_tm_to_time64(&alm.time);
-		retval = sprintf(buf, "%lld\n", alarm);
-	}
+	if (retval)
+		return retval;
 
-	return retval;
+	if (alm.enabled)
+		return sysfs_emit(buf, "%lld\n", rtc_tm_to_time64(&alm.time));
+
+	return 0;
 }
 
 static ssize_t
@@ -222,10 +218,10 @@ offset_show(struct device *dev, struct device_attribute *attr, char *buf)
 	long offset;
 
 	retval = rtc_read_offset(to_rtc_device(dev), &offset);
-	if (retval == 0)
-		retval = sprintf(buf, "%ld\n", offset);
+	if (retval)
+		return retval;
 
-	return retval;
+	return sysfs_emit(buf, "%ld\n", offset);
 }
 
 static ssize_t
@@ -246,8 +242,8 @@ static DEVICE_ATTR_RW(offset);
 static ssize_t
 range_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
-		       to_rtc_device(dev)->range_max);
+	return sysfs_emit(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
+			  to_rtc_device(dev)->range_max);
 }
 static DEVICE_ATTR_RO(range);
 
-- 
2.47.2

Re: [PATCH v1 1/1] rtc: sysfs: Use sysfs_emit() to instead of s*printf()

[Alexandre Belloni]

On Wed, 02 Jul 2025 09:15:34 +0300, Andy Shevchenko wrote:
> Follow the advice of the Documentation/filesystems/sysfs.rst that show()
> should only use sysfs_emit() or sysfs_emit_at() when formatting the value
> to be returned to user space.
> 
> 

Applied, thanks!

[1/1] rtc: sysfs: Use sysfs_emit() to instead of s*printf()
      https://git.kernel.org/abelloni/c/4dda8df717b7

Best regards,

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com