Re: [PATCH 3/8] printk: Separate code for adding/updating preferred console metadata

[John Ogness]

On 2026-02-19, Petr Mladek <pmladek@xxxxxxxx> wrote:
>> On 2026-02-06, Petr Mladek <pmladek@xxxxxxxx> wrote:
>> > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
>> > index 3f856a438e74..ee57c7ac9d02 100644
>> > --- a/kernel/printk/printk.c
>> > +++ b/kernel/printk/printk.c
>> > @@ -2491,18 +2491,82 @@ asmlinkage __visible void early_printk(const char *fmt, ...)
>> >  }
>> >  #endif
>> >  
>> > -static void set_user_specified(struct preferred_console *pc, bool user_specified)
>> > +static int update_preferred_console(int i, const char *name, const short idx,
>> 
>> Perhaps @i should be unsigned in order to guarantee no possibility of
>> negative array indexing.
>> 
>> It would need to be defined that way in __add_preferred_console() as well.
>
> Makes sense. I'll do it in v2.

Note that it might cause some warnings due to comparing signed and
unsigned. It might be preferrable to check for non-negative rather than
making it unsigned.

> I am preparing v2 and added this:
>
> /** update_preferred_console - Update a given entry in the preferred_consoles[]
>  *	table.
>  * @i: index of the entry in @preferred_consoles table which should get updated.
>  * @name: The name of the preferred console driver.
>  * @idx: Preferred console index, e.g. port number.
>  * @devname: The name of the preferred physical device.
>  * @options: Options used when setting up the console driver.
>  * @brl_options: Options used when setting up the console driver
>  *	as a braille console.
>  * @user_specified: True if preferred via the kernel command line.
>  *
>  * The function ensures that the given values are consistent. Also
>  * it updates some global variables which are used to make the right
>  * decisions in register_console().
>  *
>  * Rules:
>  *
>  *   1. Either @name and valid @idx OR @devname and @idx=-1 are allowed.
>  *	Note that a valid @name and @idx will get assigned later when
>  *	@devname matches during the device initialization.
>  *   2. Specify @brl_options if the console should be enabled as
>  *	a Braille console [*]
>  *   3. Only matching entries can be updated.
>  *   4. @options passed via the command line are used when the same
>  *	console is is preferred also by some platform-specific code.
>  *
>  * [*] Braille console is using the mechanism for registering consoles
>  *     but it is very special. It is primary used for an user interaction
>  *     with the system.

Grammar fixup:

It is primarily used for user interaction with the system.
>  *     with the system. It neither gets printk() messages nor is
>  *     associated with /dev/cosnole.

/dev/console spelled wrong.

>  */

Otherwise, LGTM.

I can provide reviewed-by tags once I look over v2.

John