[PATCH] ALSA: control: Fix parsing of numeric fields

[PATCH] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

parse_uint() passes the remaining input string to kstrtoull().

When the input contains comma-separated fields, the string
contains both the numeric value and the following fields.

For example, with:

device=1,subdevice=0,name=Master

kstrtoull() receives "1,subdevice=0,name=Master" and fails
to parse the numeric value.

Stop parsing at the next comma and pass only the numeric
field to kstrtouint().

This allows numeric fields to be parsed correctly in
comma-separated input.

Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
---
 sound/core/control_led.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 501387287ae6..3f54af2cb505 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -458,11 +458,19 @@ static char *find_eos(char *s)
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = s;
+	char delimiter;
+
+	while (*end && *end != ',')
+		end++;
+
+	delimiter = *end;
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+
+	return delimiter ? end + 1 : end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
-- 
2.55.0

[PATCH v2] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

parse_uint() passes the remaining input string to kstrtoull().

When the input contains comma-separated fields, the string
contains both the numeric value and the following fields.

For example, with:

device=1,subdevice=0,name=Master

kstrtoull() receives "1,subdevice=0,name=Master" and fails
to parse the numeric value.

Stop parsing at the next comma and pass only the numeric
field to kstrtouint().

This allows numeric fields to be parsed correctly in
comma-separated input.

Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")

Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
---
v2:
 - Add the Fixes trailer.

 sound/core/control_led.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 501387287ae6..3f54af2cb505 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -458,11 +458,19 @@ static char *find_eos(char *s)
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = s;
+	char delimiter;
+
+	while (*end && *end != ',')
+		end++;
+
+	delimiter = *end;
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+
+	return delimiter ? end + 1 : end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
-- 
2.55.0

Re: [PATCH v2] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

Hi Takashi,

I looked into using simple_strtoul(), but noticed that it is deprecated. 
kstrtoul() does not provide an end pointer either.

Would it be reasonable to retain the delimiter-first approach with 
kstrtouint(), as in v2?

Thanks,
Sreeraj

Re: [PATCH v2] ALSA: control: Fix parsing of numeric fields

[Takashi Iwai]

On Sun, 08 Nov 2026 10:54:30 +0100,
Sreeraj S Kurup wrote:
> 
> Hi Takashi,
> 
> I looked into using simple_strtoul(), but noticed that it is deprecated. 
> kstrtoul() does not provide an end pointer either.

Yes, that's also my concern about that approach.

> Would it be reasonable to retain the delimiter-first approach with 
> kstrtouint(), as in v2?

I depends on the result :)  We can compare.


thanks,

Takashi

Re: [PATCH v2] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

Hi Takashi,

I compared the approaches.

Using simple_strtoul() would provide an end pointer, but it is deprecated.

Another option is to retain kstrtoull() from the original implementation 
and apply the delimiter-first approach. This would minimize changes to the 
existing conversion logic.

However, since the destination is an unsigned int, kstrtouint() better matches 
the destination type and also detects values outside the unsigned int range.

I currently prefer the v2 approach, but wanted to point out this difference in 
overflow handling.

Thanks,
Sreeraj

Re: [PATCH v2] ALSA: control: Fix parsing of numeric fields

[Takashi Iwai]

On Sun, 08 Nov 2026 12:18:48 +0100,
Sreeraj S Kurup wrote:
> 
> Hi Takashi,
> 
> I compared the approaches.
> 
> Using simple_strtoul() would provide an end pointer, but it is deprecated.
> 
> Another option is to retain kstrtoull() from the original implementation 
> and apply the delimiter-first approach. This would minimize changes to the 
> existing conversion logic.
> 
> However, since the destination is an unsigned int, kstrtouint() better matches 
> the destination type and also detects values outside the unsigned int range.
> 
> I currently prefer the v2 approach, but wanted to point out this difference in 
> overflow handling.

OK, thanks.  Feel free to resubmit whatever you find better :)


Takashi

Re: [PATCH v2] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

Hi Takashi,

Thanks. I'll resubmit v2.

Thanks, Sreeraj

[PATCH v3] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

parse_uint() passes the remaining input string to kstrtoull().

When the input contains comma-separated fields, the string
contains both the numeric value and the following fields.

For example, with:

device=1,subdevice=0,name=Master

kstrtoull() receives "1,subdevice=0,name=Master" and fails
to parse the numeric value.

Stop parsing at the next comma and pass only the numeric
field to kstrtouint().

This allows numeric fields to be parsed correctly in
comma-separated input.

Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
---
v3:
 - No code changes. Retain the v2 implementation after
   comparing the alternative approaches.
v2:
 - Add the Fixes trailer.

 sound/core/control_led.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 501387287ae6..3f54af2cb505 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -458,11 +458,19 @@ static char *find_eos(char *s)
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = s;
+	char delimiter;
+
+	while (*end && *end != ',')
+		end++;
+
+	delimiter = *end;
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+
+	return delimiter ? end + 1 : end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
-- 
2.55.0

Re: [PATCH v3] ALSA: control: Fix parsing of numeric fields

[Manuel Ebner]

On Sun, 2026-11-08 at 12:48 +0000, Sreeraj S Kurup wrote:
> parse_uint() passes the remaining input string to kstrtoull().
> 
> When the input contains comma-separated fields, the string
> contains both the numeric value and the following fields.
> 
> For example, with:
> 
> device=1,subdevice=0,name=Master
> 
> kstrtoull() receives "1,subdevice=0,name=Master" and fails
> to parse the numeric value.
> 
> Stop parsing at the next comma and pass only the numeric
> field to kstrtouint().
> 
> This allows numeric fields to be parsed correctly in
> comma-separated input.
> 
> Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
> Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>

Reviewed-by: Manuel Ebner

> ---
> v3:
>  - No code changes. Retain the v2 implementation after
>    comparing the alternative approaches.
> v2:
>  - Add the Fixes trailer.
> 
>  sound/core/control_led.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/core/control_led.c b/sound/core/control_led.c
> index 501387287ae6..3f54af2cb505 100644
> --- a/sound/core/control_led.c
> +++ b/sound/core/control_led.c
> @@ -458,11 +458,19 @@ static char *find_eos(char *s)
>  
>  static char *parse_uint(char *s, unsigned int *val)
>  {
> -	unsigned long long res;
> -	if (kstrtoull(s, 10, &res))
> -		res = 0;
> -	*val = res;
> -	return find_eos(s);
> +	char *end = s;
> +	char delimiter;
> +
> +	while (*end && *end != ',')
> +		end++;
> +
> +	delimiter = *end;
> +	*end = '\0';
> +	if (kstrtouint(s, 10, val))
> +		*val = 0;
> +	*end = delimiter;
> +
> +	return delimiter ? end + 1 : end;
>  }
>  
>  static char *parse_string(char *s, char *val, size_t val_size)

Re: [PATCH v3] ALSA: control: Fix parsing of numeric fields

[Takashi Iwai]

On Sun, 08 Nov 2026 13:48:32 +0100,
Sreeraj S Kurup wrote:
> 
> parse_uint() passes the remaining input string to kstrtoull().
> 
> When the input contains comma-separated fields, the string
> contains both the numeric value and the following fields.
> 
> For example, with:
> 
> device=1,subdevice=0,name=Master
> 
> kstrtoull() receives "1,subdevice=0,name=Master" and fails
> to parse the numeric value.
> 
> Stop parsing at the next comma and pass only the numeric
> field to kstrtouint().
> 
> This allows numeric fields to be parsed correctly in
> comma-separated input.
> 
> Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
> Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
> ---
> v3:
>  - No code changes. Retain the v2 implementation after
>    comparing the alternative approaches.
> v2:
>  - Add the Fixes trailer.

I think a bit more easier to understand the code flow would to make
each parse_*() function returning the substring end position, instead
of the next substring.  (BTW, this fits more with the function name
find_eos(). too).

The main loop in set_led_id() already treats it, 

	while (*s) {
		os = s;	
		....
		if (*s == ',')
			s++;
		if (s == os)
			break;
	}

Both parse_uint() and parse_iface() return find_eos() value as is.
parse_string() has an extra increment for the next substring, so we
just need to drop it.

That is, what we need to change is something like:

--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -451,22 +451,24 @@ static const struct attribute_group *snd_ctl_led_dev_attr_groups[] = {
 	NULL,
 };
 
+/* return the end of substring pointing to either comma or NUL */
 static char *find_eos(char *s)
 {
 	while (*s && *s != ',')
 		s++;
-	if (*s)
-		s++;
 	return s;
 }
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = find_eos(s);
+	char delimiter = *end;
+
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+	return end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
@@ -491,8 +493,6 @@ static char *parse_string(char *s, char *val, size_t val_size)
 		}
 	}
 	*val = '\0';
-	if (*s)
-		s++;
 	return s;
 }
 

thanks,

Takashi

Re: [PATCH v3] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

Hi Takashi,

Thanks for the suggestion.

I've updated the patch accordingly. All parse_*() functions 
now return the end of the current substring, leaving comma 
handling to set_led_id().

I've also updated parse_uint() to temporarily terminate the 
numeric substring before calling kstrtouint().

Please find the updated v4 patch.

Thanks,
Sreeraj

[PATCH v4] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

parse_uint() passes the remaining input string to kstrtoull().

When the input contains comma-separated fields, the string
contains both the numeric value and the following fields.

For example, with:

device=1,subdevice=0,name=Master

kstrtoull() receives "1,subdevice=0,name=Master" and fails
to parse the numeric value.

Stop parsing at the next comma and pass only the numeric
field to kstrtouint().

Make all parse_*() functions return the end of the current
substring, leaving delimiter handling to set_led_id().
Temporarily terminate the numeric substring in parse_uint()
before calling kstrtouint().

This allows numeric fields to be parsed correctly in
comma-separated input.

Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
---
v4:
 - Make parse_*() functions consistently return the end of
   the current substring.
 - Let set_led_id() handle comma advancement.
 - Use kstrtouint() after temporarily terminating the
   numeric substring.
v3:
 - No code changes. Retain the v2 implementation after
   comparing the alternative approaches.
v2:
 - Add the Fixes trailer.

 sound/core/control_led.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 501387287ae6..1b0473b71c3c 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -447,22 +447,23 @@ static const struct attribute_group *snd_ctl_led_dev_attr_groups[] = {
 	NULL,
 };
 
+/* return the end of substring pointing to either comma or NUL */
 static char *find_eos(char *s)
 {
 	while (*s && *s != ',')
 		s++;
-	if (*s)
-		s++;
 	return s;
 }
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = find_eos(s);
+	char delimiter = *end;
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+	return end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
@@ -487,8 +488,6 @@ static char *parse_string(char *s, char *val, size_t val_size)
 		}
 	}
 	*val = '\0';
-	if (*s)
-		s++;
 	return s;
 }
 
-- 
2.55.0

[PATCH v5] ALSA: control: Fix parsing of numeric fields

[Sreeraj S Kurup]

parse_uint() passes the remaining input string to kstrtoull().

When the input contains comma-separated fields, the string
contains both the numeric value and the following fields.

For example, with:

device=1,subdevice=0,name=Master

kstrtoull() receives "1,subdevice=0,name=Master" and fails
to parse the numeric value.

Stop parsing at the next comma and pass only the numeric
field to kstrtouint().

Make all parse_*() functions return the end of the current
substring, leaving delimiter handling to set_led_id().
Temporarily terminate the numeric substring in parse_uint()
before calling kstrtouint().

This allows numeric fields to be parsed correctly in
comma-separated input.

Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
Signed-off-by: Sreeraj S Kurup <sreekuttan2156239@gmail.com>
---
v5:
 - Advance past the closing quote in the quoted-string
   branch of parse_string().
 - Ensure parse_string() returns the end of the current
   substring for both quoted and unquoted strings.
v4:
 - Make parse_*() functions consistently return the end of
   the current substring.
 - Let set_led_id() handle comma advancement.
 - Use kstrtouint() after temporarily terminating the
   numeric substring.
v3:
 - No code changes. Retain the v2 implementation after
   comparing the alternative approaches.
v2:
 - Add the Fixes trailer.

 sound/core/control_led.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 501387287ae6..1aadacfbd3c4 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -447,22 +447,23 @@ static const struct attribute_group *snd_ctl_led_dev_attr_groups[] = {
 	NULL,
 };
 
+/* return the end of substring pointing to either comma or NUL */
 static char *find_eos(char *s)
 {
 	while (*s && *s != ',')
 		s++;
-	if (*s)
-		s++;
 	return s;
 }
 
 static char *parse_uint(char *s, unsigned int *val)
 {
-	unsigned long long res;
-	if (kstrtoull(s, 10, &res))
-		res = 0;
-	*val = res;
-	return find_eos(s);
+	char *end = find_eos(s);
+	char delimiter = *end;
+	*end = '\0';
+	if (kstrtouint(s, 10, val))
+		*val = 0;
+	*end = delimiter;
+	return end;
 }
 
 static char *parse_string(char *s, char *val, size_t val_size)
@@ -477,6 +478,8 @@ static char *parse_string(char *s, char *val, size_t val_size)
 			}
 			s++;
 		}
+		if (*s)
+			s++;
 	} else {
 		while (*s && *s != ',') {
 			if (val_size > 1) {
@@ -487,8 +490,6 @@ static char *parse_string(char *s, char *val, size_t val_size)
 		}
 	}
 	*val = '\0';
-	if (*s)
-		s++;
 	return s;
 }
 
-- 
2.55.0