On 2023-03-09, Petr Mladek <pmladek@xxxxxxxx> wrote: >> --- a/kernel/printk/printk.c >> +++ b/kernel/printk/printk.c >> @@ -3472,6 +3492,14 @@ void register_console(struct console *newcon) >> newcon->dropped = 0; >> console_init_seq(newcon, bootcon_registered); >> >> + if (!(newcon->flags & CON_NO_BKL)) >> + have_bkl_console = true; > > We never clear this value even when the console gets unregistered. OK. I'll allow it to be cleared on unregister by checking the registered list. >> @@ -3515,6 +3543,9 @@ void register_console(struct console *newcon) >> if (con->flags & CON_BOOT) >> unregister_console_locked(con); >> } >> + >> + /* All boot consoles have been unregistered. */ >> + have_boot_console = false; > > The boot consoles can be removed also by printk_late_init(). > > I would prefer to make this more error-proof and update both > have_bkl_console and have_boot_console in unregister_console(). OK. > A solution would be to use a reference counter instead of the boolean. > I am not sure if it is worth it. But it seems that refcount_read() > is just simple atomic read, aka READ_ONCE(). Well, we are holding the console_list_lock, so we can just iterate over the list. Iteration happens later in the series anyway, in order to create/run the NOBKL threads. John
