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

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

[Thorsten Blum]

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@linux.dev>
---
 .../platform/x86/dell/dell-wmi-sysman/sysman.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 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..0f24cecc93fc 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 +144,14 @@ 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]);
-		else
-			buf += sprintf(buf, "%s ", reset_types[i]);
-	}
-	buf += sprintf(buf, "\n");
-	return buf-start;
+	for (i = 0; i < MAX_TYPES; i++)
+		len += sysfs_emit_at(buf, len, i == reset_option ? "[%s] " : "%s ",
+				     reset_types[i]);
+	len += sysfs_emit_at(buf, len, "\n");
+	return len;
 }
 
 /**
@@ -194,7 +192,7 @@ 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@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

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

[Ilpo Järvinen]

On Thu, 5 Mar 2026, Thorsten Blum wrote:

> 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@linux.dev>
> ---
>  .../platform/x86/dell/dell-wmi-sysman/sysman.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 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..0f24cecc93fc 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 +144,14 @@ 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]);
> -		else
> -			buf += sprintf(buf, "%s ", reset_types[i]);
> -	}
> -	buf += sprintf(buf, "\n");
> -	return buf-start;
> +	for (i = 0; i < MAX_TYPES; i++)
> +		len += sysfs_emit_at(buf, len, i == reset_option ? "[%s] " : "%s ",

Are all checkers okay with this construct? IIRC something doesn't 
like having such logic in where only a formatting string is expected.

--
 i.

> +				     reset_types[i]);
> +	len += sysfs_emit_at(buf, len, "\n");
> +	return len;
>  }
>  
>  /**
> @@ -194,7 +192,7 @@ 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);
> 

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

[Thorsten Blum]

On 5. Mar 2026, at 13:48, Ilpo Järvinen wrote:
> On Thu, 5 Mar 2026, Thorsten Blum wrote:
>> 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@linux.dev>
>> ---
>> .../platform/x86/dell/dell-wmi-sysman/sysman.c | 18 ++++++++----------
>> 1 file changed, 8 insertions(+), 10 deletions(-)
>> [...]
>> +	for (i = 0; i < MAX_TYPES; i++)
>> +		len += sysfs_emit_at(buf, len, i == reset_option ? "[%s] " : "%s ",
> 
> Are all checkers okay with this construct? IIRC something doesn't 
> like having such logic in where only a formatting string is expected.

You mean checkpatch? No warnings, but I can split it again if needed.

Thanks,
Thorsten

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

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 1237 bytes --]

On Thu, 5 Mar 2026, Thorsten Blum wrote:
> On 5. Mar 2026, at 13:48, Ilpo Järvinen wrote:
> > On Thu, 5 Mar 2026, Thorsten Blum wrote:
> >> 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@linux.dev>
> >> ---
> >> .../platform/x86/dell/dell-wmi-sysman/sysman.c | 18 ++++++++----------
> >> 1 file changed, 8 insertions(+), 10 deletions(-)
> >> [...]
> >> +	for (i = 0; i < MAX_TYPES; i++)
> >> +		len += sysfs_emit_at(buf, len, i == reset_option ? "[%s] " : "%s ",
> > 
> > Are all checkers okay with this construct? IIRC something doesn't 
> > like having such logic in where only a formatting string is expected.
> 
> You mean checkpatch? No warnings, but I can split it again if needed.

Unfortunately, I don't recall what it was anymore (I didn't expect it 
to be checkpatch) and couldn't locate the change either but I'm pretty 
sure somebody did split a similar elvis operator.

-- 
 i.