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From: John Ogness <john.ogness@linutronix.de>
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 <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
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;
}
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