[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