linux-kernel - [PATCH v2] comedi: Convert snprintf() to sysfs

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Message-ID: <YzRK3Ye3FKTe8p4y@octinomon>
Date:   Wed, 28 Sep 2022 14:23:41 +0100
From:   Jules Irenge <jbi.octave@...il.com>
To:     gregkh@...uxfoundation.org
Cc:     hsweeten@...ionengravers.com, abbotti@....co.uk,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] comedi: Convert snprintf() to sysfs_emit()

Coccinnelle reports a warning
Warning: Use scnprintf or sprintf

Adding to that, there has been a slow migration from snprintf to scnprintf.
This LWN article explains the rationale for this change

https: //lwn.net/Articles/69419/
ie. snprintf() returns what *would* be the resulting length,
 while scnprintf() returns the actual length.

However following the advice on
https://www.kernel.org/doc/html/latest/filesystems/sysfs.html

For show(device *...) functions we should only use sysfs_emit() or sysfs_emit_at()
 especially when formatting the value to be returned to user space.

Hence here
We convert to sysfs_emit() that even does better and shorten the code
using the same rationale of scnprintf()

Signed-off-by: Jules Irenge <jules.irenge@...tgrad.manchester.ac.uk>
---

v2: Replace scnprintf() with sysfs_emit()

 drivers/comedi/comedi_fops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index 55a0cae04b8d..a6017fafcb2a 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -396,7 +396,7 @@ static ssize_t max_read_buffer_kb_show(struct device *csdev,
 	mutex_unlock(&dev->mutex);
 
 	comedi_dev_put(dev);
-	return snprintf(buf, PAGE_SIZE, "%u\n", size);
+	return sysfs_emit(buf, "%u\n", size);
 }
 
 static ssize_t max_read_buffer_kb_store(struct device *csdev,
-- 
2.37.3