linux-kernel - [PATCH][next] mips: sgi-ip22: Replace "s[n]?printf" with sysfs

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Message-ID: <Zw2GRQkbx8Z8DlcS@mail.google.com>
Date: Tue, 15 Oct 2024 09:59:49 +1300
From: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@...il.com>
To: tsbogend@...ha.franken.de, gregkh@...uxfoundation.org,
	zhanggenjian@...inos.cn, ricardo@...liere.net, bvanassche@....org,
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: paulo.miguel.almeida.rodenas@...il.com, linux-hardening@...r.kernel.org
Subject: [PATCH][next] mips: sgi-ip22: Replace "s[n]?printf" with sysfs_emit
 in sysfs callbacks

snprintf() has the documented, but still rather strange trait of
returning the length of the data that *would have been* written to the
array if space were available, rather than the arguably more useful
length of data *actually* written, it is usually considered wise to use
scnprintf()/vscnprintf() instead. In the case of sysfs call-backs,
new wrappers exist that do just that while also being PAGE_SIZE aware

This patch updates the sysfs .show() callbacks to use the sysfs_emit()
helper instead of snprintf() and sprintf().

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@...il.com>
---
 arch/mips/sgi-ip22/ip22-gio.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/mips/sgi-ip22/ip22-gio.c b/arch/mips/sgi-ip22/ip22-gio.c
index d20eec742bfa..5893ea4e382c 100644
--- a/arch/mips/sgi-ip22/ip22-gio.c
+++ b/arch/mips/sgi-ip22/ip22-gio.c
@@ -165,9 +165,8 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
 			     char *buf)
 {
 	struct gio_device *gio_dev = to_gio_device(dev);
-	int len = snprintf(buf, PAGE_SIZE, "gio:%x\n", gio_dev->id.id);
 
-	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
+	return sysfs_emit(buf, "gio:%x\n", gio_dev->id.id);
 }
 static DEVICE_ATTR_RO(modalias);
 
@@ -177,7 +176,7 @@ static ssize_t name_show(struct device *dev,
 	struct gio_device *giodev;
 
 	giodev = to_gio_device(dev);
-	return sprintf(buf, "%s", giodev->name);
+	return sysfs_emit(buf, "%s\n", giodev->name);
 }
 static DEVICE_ATTR_RO(name);
 
@@ -187,7 +186,7 @@ static ssize_t id_show(struct device *dev,
 	struct gio_device *giodev;
 
 	giodev = to_gio_device(dev);
-	return sprintf(buf, "%x", giodev->id.id);
+	return sysfs_emit(buf, "%x\n", giodev->id.id);
 }
 static DEVICE_ATTR_RO(id);
 
-- 
2.47.0