Per filesystems/sysfs.rst, show() should only use sysfs_emit()
or sysfs_emit_at() when formatting the value to be returned to user space.

coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().

> ./drivers/ptp/ptp_sysfs.c:27:8-16: WARNING: please use sysfs_emit

No functional change intended

CC: Richard Cochran <richardcochran@gmail.com>
CC: netdev@vger.kernel.org
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
---
V2:
- Address Rahul's comments:
  Convert all leftover snprintf that is not detected by coccinelle to sysfs_emit
-
  V2: extract patch from the patch set[1] so that maintainer can review/accept it separately.
  [1] https://lore.kernel.org/lkml/20240116041129.3937800-1-lizhijian@fujitsu.com/
---
 drivers/ptp/ptp_sysfs.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
index f7a499a1bd39..a15460aaa03b 100644
--- a/drivers/ptp/ptp_sysfs.c
+++ b/drivers/ptp/ptp_sysfs.c
@@ -24,8 +24,7 @@ static ssize_t max_phase_adjustment_show(struct device *dev,
 {
 	struct ptp_clock *ptp = dev_get_drvdata(dev);
 
-	return snprintf(page, PAGE_SIZE - 1, "%d\n",
-			ptp->info->getmaxphase(ptp->info));
+	return sysfs_emit(page, "%d\n", ptp->info->getmaxphase(ptp->info));
 }
 static DEVICE_ATTR_RO(max_phase_adjustment);
 
@@ -34,7 +33,7 @@ static ssize_t var##_show(struct device *dev,				\
 			   struct device_attribute *attr, char *page)	\
 {									\
 	struct ptp_clock *ptp = dev_get_drvdata(dev);			\
-	return snprintf(page, PAGE_SIZE-1, "%d\n", ptp->info->var);	\
+	return sysfs_emit(page, "%d\n", ptp->info->var);	\
 }									\
 static DEVICE_ATTR(name, 0444, var##_show, NULL);
 
@@ -102,8 +101,8 @@ static ssize_t extts_fifo_show(struct device *dev,
 	if (!qcnt)
 		goto out;
 
-	cnt = snprintf(page, PAGE_SIZE, "%u %lld %u\n",
-		       event.index, event.t.sec, event.t.nsec);
+	cnt = sysfs_emit(page, "%u %lld %u\n",
+			 event.index, event.t.sec, event.t.nsec);
 out:
 	return cnt;
 }
@@ -194,7 +193,7 @@ static ssize_t n_vclocks_show(struct device *dev,
 	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
 		return -ERESTARTSYS;
 
-	size = snprintf(page, PAGE_SIZE - 1, "%u\n", ptp->n_vclocks);
+	size = sysfs_emit(page, "%u\n", ptp->n_vclocks);
 
 	mutex_unlock(&ptp->n_vclocks_mux);
 
@@ -270,7 +269,7 @@ static ssize_t max_vclocks_show(struct device *dev,
 	struct ptp_clock *ptp = dev_get_drvdata(dev);
 	ssize_t size;
 
-	size = snprintf(page, PAGE_SIZE - 1, "%u\n", ptp->max_vclocks);
+	size = sysfs_emit(page, "%u\n", ptp->max_vclocks);
 
 	return size;
 }
-- 
2.29.2

On Thu, Jan 25, 2024 at 09:53:29AM +0800, Li Zhijian wrote:
> Per filesystems/sysfs.rst, show() should only use sysfs_emit()
> or sysfs_emit_at() when formatting the value to be returned to user space.
> 
> coccinelle complains that there are still a couple of functions that use
> snprintf(). Convert them to sysfs_emit().
> 
> > ./drivers/ptp/ptp_sysfs.c:27:8-16: WARNING: please use sysfs_emit
> 
> No functional change intended

Acked-by: Richard Cochran <richardcochran@gmail.com>