From: John Ogness Date: Mon, 11 Dec 2023 09:36:52 +0000 Subject: [PATCH 30/50] printk: Track nbcon consoles Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.7/older/patches-6.7-rt6.tar.xz Add a global flag @have_nbcon_console to identify if any nbcon consoles are registered. This will be used in follow-up commits to preserve legacy behavior when no nbcon consoles are registered. Signed-off-by: John Ogness Signed-off-by: Sebastian Andrzej Siewior --- kernel/printk/printk.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -471,6 +471,13 @@ static DEFINE_MUTEX(syslog_lock); bool have_legacy_console; /* + * Specifies if an nbcon console is registered. If nbcon consoles are present, + * synchronous printing of legacy consoles will not occur during panic until + * the backtrace has been stored to the ringbuffer. + */ +bool have_nbcon_console; + +/* * Specifies if a boot console is registered. If boot consoles are present, * nbcon consoles cannot print simultaneously and must be synchronized by * the console lock. This is because boot consoles and nbcon consoles may @@ -3530,6 +3537,7 @@ void register_console(struct console *ne console_init_seq(newcon, bootcon_registered); if (newcon->flags & CON_NBCON) { + have_nbcon_console = true; nbcon_init(newcon); } else { have_legacy_console = true; @@ -3591,6 +3599,7 @@ EXPORT_SYMBOL(register_console); static int unregister_console_locked(struct console *console) { bool found_legacy_con = false; + bool found_nbcon_con = false; bool found_boot_con = false; struct console *c; int res; @@ -3647,13 +3656,18 @@ static int unregister_console_locked(str for_each_console(c) { if (c->flags & CON_BOOT) found_boot_con = true; - if (!(c->flags & CON_NBCON)) + + if (c->flags & CON_NBCON) + found_nbcon_con = true; + else found_legacy_con = true; } if (!found_boot_con) have_boot_console = false; if (!found_legacy_con) have_legacy_console = false; + if (!found_nbcon_con) + have_nbcon_console = false; return res; }