[PATCH] printk: Remove console options before decoding the name

[PATCH] printk: Remove console options before decoding the name

[David Engraf]

This fixes a regression when a console option includes ':'. Commit
7640f1a44eba ("printk: Add match_devname_and_update_preferred_console()")
introduced console=DEVNAME:0.0 hardware style addressing by looking for a
colon. If the colon is part of an option the name is handled as devname
instead of ttyname.

Fix by handling the options first which will add a NULL terminator to the
string.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
---
 kernel/printk/printk.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6d3d18a50da74..c297a0ae04f7b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2646,24 +2646,22 @@ static int __init console_setup(char *str)
 	if (_braille_console_setup(&str, &brl_options))
 		return 1;
 
+	/* Decode str into name, index, options */
+	options = strchr(str, ',');
+	if (options)
+		*(options++) = 0;
+
 	/* For a DEVNAME:0.0 style console the character device is unknown early */
 	if (strchr(str, ':'))
 		devname = buf;
 	else
 		ttyname = buf;
 
-	/*
-	 * Decode str into name, index, options.
-	 */
 	if (ttyname && isdigit(str[0]))
 		scnprintf(buf, sizeof(buf), "ttyS%s", str);
 	else
 		strscpy(buf, str);
 
-	options = strchr(str, ',');
-	if (options)
-		*(options++) = 0;
-
 #ifdef __sparc__
 	if (!strcmp(str, "ttya"))
 		strscpy(buf, "ttyS0");
-- 
2.53.0

Re: [PATCH] printk: Remove console options before decoding the name

[Tony Lindgren]

On Wed, Sep 16, 2026 at 08:32:18AM +0300, David Engraf wrote:
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2646,24 +2646,22 @@ static int __init console_setup(char *str)
>  	if (_braille_console_setup(&str, &brl_options))
>  		return 1;
>  
> +	/* Decode str into name, index, options */
> +	options = strchr(str, ',');
> +	if (options)
> +		*(options++) = 0;
> +

How about update the comment for why it needs to be first?

Maybe something like:

Decode str into options first. The options may contain a ':' used also
for DEVNAME.

Re: [PATCH] printk: Remove console options before decoding the name

[David Engraf]

On 16.09.26 08:48 wrote Tony Lindgren:
> On Wed, Sep 16, 2026 at 08:32:18AM +0300, David Engraf wrote:
>> --- a/kernel/printk/printk.c
>> +++ b/kernel/printk/printk.c
>> @@ -2646,24 +2646,22 @@ static int __init console_setup(char *str)
>>   	if (_braille_console_setup(&str, &brl_options))
>>   		return 1;
>>   
>> +	/* Decode str into name, index, options */
>> +	options = strchr(str, ',');
>> +	if (options)
>> +		*(options++) = 0;
>> +
> 
> How about update the comment for why it needs to be first?
> 
> Maybe something like:
> 
> Decode str into options first. The options may contain a ':' used also
> for DEVNAME.

Okay I can update the comment if there are no other objections.

Best regards
- David

[PATCH v2] printk: Remove console options before decoding the name

[David Engraf]

This fixes a regression when a console option includes ':'. Commit
7640f1a44eba ("printk: Add match_devname_and_update_preferred_console()")
introduced console=DEVNAME:0.0 hardware style addressing by looking for a
colon. If the colon is part of an option the name is handled as devname
instead of ttyname.

Fix by handling the options first which will add a NULL terminator to the
string.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
---
 kernel/printk/printk.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6d3d18a50da74..f4803fe05a0aa 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2646,24 +2646,25 @@ static int __init console_setup(char *str)
 	if (_braille_console_setup(&str, &brl_options))
 		return 1;
 
+	/*
+	 * Decode str into name, index and options. Start with options, since
+	 * it might also contain a ':' used for DEVNAME.
+	 */
+	options = strchr(str, ',');
+	if (options)
+		*(options++) = 0;
+
 	/* For a DEVNAME:0.0 style console the character device is unknown early */
 	if (strchr(str, ':'))
 		devname = buf;
 	else
 		ttyname = buf;
 
-	/*
-	 * Decode str into name, index, options.
-	 */
 	if (ttyname && isdigit(str[0]))
 		scnprintf(buf, sizeof(buf), "ttyS%s", str);
 	else
 		strscpy(buf, str);
 
-	options = strchr(str, ',');
-	if (options)
-		*(options++) = 0;
-
 #ifdef __sparc__
 	if (!strcmp(str, "ttya"))
 		strscpy(buf, "ttyS0");
-- 
2.53.0

Re: [PATCH v2] printk: Remove console options before decoding the name

[Tony Lindgren]

On Thu, Sep 17, 2026 at 09:05:51AM +0300, David Engraf wrote:
> This fixes a regression when a console option includes ':'. Commit
> 7640f1a44eba ("printk: Add match_devname_and_update_preferred_console()")
> introduced console=DEVNAME:0.0 hardware style addressing by looking for a
> colon. If the colon is part of an option the name is handled as devname
> instead of ttyname.

Just curious, which console did you hit this issue with?

In any case, thanks for updating the comments:

Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>