Commit 4c3ba0d5 authored by Petr Mladek's avatar Petr Mladek
Browse files

printk/nbcon/panic: Allow printk kthread to sleep when the system is in panic 



The printk kthread might be running when there is a panic in progress.
But it is not able to acquire the console ownership any longer.

Prevent the desperate attempts to acquire the ownership and allow sleeping
in panic. It would make it behave the same as when there is any CPU
in an emergency context.

Reviewed-by: default avatarAndrew Murray <amurray@thegoodpenguin.co.uk>
Reviewed-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20250926124912.243464-3-pmladek@suse.com


[pmladek@suse.com: Rebased on top of 6.18-rc1 (panic_in_progress() moved to panic.c)]
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent c41c0ebf

kernel/printk/nbcon.c

+4 −2
Original line number Diff line number Diff line
@@ -1173,7 +1173,8 @@ static bool nbcon_kthread_should_wakeup(struct console *con, struct nbcon_contex 
	 * where the context with a higher priority takes over the nbcon console

	 * ownership in the middle of a message.

	 */

	if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)))

	if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)) ||

	    unlikely(panic_in_progress()))

		return false;



	cookie = console_srcu_read_lock();
@@ -1231,7 +1232,8 @@ static int nbcon_kthread_func(void *__console) 
		 * Block the kthread when the system is in an emergency or panic

		 * mode. See nbcon_kthread_should_wakeup() for more details.

		 */

		if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)))

		if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)) ||

		    unlikely(panic_in_progress()))

			goto wait_for_event;



		backlog = false;