Re: [PATCH] printk: Set console_set_on_cmdline=1 when using console="" or console=null

Petr Mladek
2022-02-08T15:55:30Z

On Fri 2022-01-28 00:00:52, Andre Kalb wrote:
> In case of using console="" or console=null set console_set_on_cmdline=1
> to disable chosen{ "stdout-path" } node from devicetree.
>
> To jump out from drivers/of/base.c, line 2087 of_console_check function
> with false.

It makes sense. I would just fix it slightly different way, see below.

> Signed-off-by: Andre Kalb <andre.kalb@sma.de>
> ---
> kernel/printk/printk.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 82abfaf3c2aa..df5ab35b8af2 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2385,6 +2385,7 @@ static int __init console_setup(char *str)
> */
> if (str[0] == 0 || strcmp(str, "null") == 0) {
> __add_preferred_console("ttynull", 0, NULL, NULL,
> true);
> + console_set_on_cmdline = 1;

We basically always need to set it when __add_preferred_console() is
called with user_specified == true.

Therefore, we should move the assigment into
__add_preferred_console(). We should do something like:

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 82abfaf3c2aa..3654695ca5d2 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2324,6 +2324,15 @@ asmlinkage __visible void early_printk(const char *fmt, ...)
}
#endif

+static void set_user_specified(struct console_cmdline *c, bool user_specified)
+{
+ if (!user_specified)
+ return;
+
+ c->user_specified = true;
+ console_set_on_cmdline = 1;
+}
+
static int __add_preferred_console(char *name, int idx, char *options,
char *brl_options, bool user_specified)
{
@@ -2340,8 +2349,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
if (strcmp(c->name, name) == 0 && c->index == idx) {
if (!brl_options)
preferred_console = i;
- if (user_specified)
- c->user_specified = true;
+ set_user_specified(c, user_specified);
return 0;
}
}
@@ -2351,7 +2359,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
preferred_console = i;
strlcpy(c->name, name, sizeof(c->name));
c->options = options;
- c->user_specified = user_specified;
+ set_user_specified(c, user_specified);
braille_set_options(c, brl_options);

c->index = idx;
@@ -2417,7 +2425,6 @@ static int __init console_setup(char *str)
*s = 0;

__add_preferred_console(buf, idx, options, brl_options, true);
- console_set_on_cmdline = 1;
return 1;
}
__setup("console=", console_setup);

Best Regards,
Petr