Hello,
On (05/15/19 16:36), Petr Mladek wrote:
[..]
> >
> > console_unlock();
> > console_sysfs_notify();
> > + console_lock();
>
> I have got an idea how to get rid of this weirdness:
>
> 1. The check for bcon seems to be just an optimization. There is not need
> to remove boot consoles when there are none.
>
> 2. The condition (newcon->flags & (CON_CONSDEV|CON_BOOT)) == CON_CONSDEV)
> is valid only when the preferred console was really added.
>
> Therefore we could move the code to a separate function, e.g.
>
> void unregister_boot_consoles(void)
> {
> struct console *bcon;
>
> console_lock();
> for_each_console(bcon)
> if (bcon->flags & CON_BOOT)
> __unregister_console(bcon);
> }
> console_unlock();
> console_sysfs_notify();
> }
>
> Then we could do something like:
>
> void register_console(struct console *newcon)
> {
> bool newcon_is_preferred = false;
>
> console_lock();
> __register_console(newcon);
> if ((newcon->flags & (CON_CONSDEV|CON_BOOT)) == CON_CONSDEV)
> newcon_is_preferred = true;
> console_unlock();
> console_sysfs_notify();
>
> /*
> * By unregistering the bootconsoles after we enable the real console
> * we get the "console xxx enabled" message on all the consoles -
> * boot consoles, real consoles, etc - this is to ensure that end
> * users know there might be something in the kernel's log buffer that
> * went to the bootconsole (that they do not see on the real console)
> */
> if (newcon_is_preferred && !keep_bootcon)
> unregister_boot_consoles();
> }
>
> How does that sound?
Hmm, may be I'm missing something. I think that the 'weirdness'
is still needed. This
console_lock();
__unregister_console(bcon); // pr_info("%sconsole disabled\n")
console_unlock();
is going to change the visible behaviour - we need to show
pr_info("%sconsole [%s%d] disabled\n") on all consoles, especially
on the console which we are disabling. Who knows, maybe that's the
last remaining properly working console. Doing __unregister_console()
under console_sem will end up in a lost/missing message on bcon (or
on any other console we are unregistering).
-ss
