[PATCH v2] platform/x86: dell-wmi-sysman: Use sysfs_emit{_at} in show functions

From: Thorsten Blum

Date: Thu Mar 05 2026 - 09:10:00 EST


Replace sprintf() with sysfs_emit() and sysfs_emit_at() in sysfs show
functions. sysfs_emit() and sysfs_emit_at() are preferred for formatting
sysfs output because they provide safer bounds checking.

In reset_bios_show(), use sysfs_emit_at() to avoid manual buffer size
accounting.

Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx>
---
Changes in v2:
- Use if-else instead of inline ternary operator (Ilpo)
- Link to v1: https://lore.kernel.org/lkml/20260305124126.255026-2-thorsten.blum@xxxxxxxxx/
---
drivers/platform/x86/dell/dell-wmi-sysman/sysman.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index 9dddab6c9397..80820451710b 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -11,6 +11,7 @@
#include <linux/dmi.h>
#include <linux/module.h>
#include <linux/kernel.h>
+#include <linux/sysfs.h>
#include <linux/wmi.h>
#include "dell-wmi-sysman.h"
#include "../../firmware_attributes_class.h"
@@ -143,17 +144,17 @@ int map_wmi_error(int error_code)
*/
static ssize_t reset_bios_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
- char *start = buf;
+ ssize_t len = 0;
int i;

for (i = 0; i < MAX_TYPES; i++) {
if (i == reset_option)
- buf += sprintf(buf, "[%s] ", reset_types[i]);
+ len += sysfs_emit_at(buf, len, "[%s] ", reset_types[i]);
else
- buf += sprintf(buf, "%s ", reset_types[i]);
+ len += sysfs_emit_at(buf, len, "%s ", reset_types[i]);
}
- buf += sprintf(buf, "\n");
- return buf-start;
+ len += sysfs_emit_at(buf, len, "\n");
+ return len;
}

/**
@@ -194,7 +195,7 @@ static ssize_t reset_bios_store(struct kobject *kobj,
static ssize_t pending_reboot_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
- return sprintf(buf, "%d\n", wmi_priv.pending_changes);
+ return sysfs_emit(buf, "%d\n", wmi_priv.pending_changes);
}

static struct kobj_attribute reset_bios = __ATTR_RW(reset_bios);
--
Thorsten Blum <thorsten.blum@xxxxxxxxx>
GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4