dump_stack: Do not get cpu_sync for panic CPU

dump_stack() is called in panic(). If for some reason another CPU
is holding the printk_cpu_sync and is unable to release it, the
panic CPU will be unable to continue and print the stacktrace.

Since non-panic CPUs are not allowed to store new printk messages
anyway, there is no need to synchronize the stacktrace output in
a panic situation.

For the panic CPU, do not get the printk_cpu_sync because it is
not needed and avoids a potential deadlock scenario in panic().

Link: https://lore.kernel.org/lkml/ZcIGKU8sxti38Kok@alley
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240207134103.1357162-15-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>

This commit is contained in:

John Ogness

2024-02-07 14:47:03 +01:06

committed by

Petr Mladek

parent d988d9a9b9

commit 7412dc6d55

3 changed files with 15 additions and 4 deletions

									
										include/linux/printk.h
									
		+2
		
												View File
												
				@@ -273,6 +273,8 @@ static inline void printk_trigger_flush(void)

				}

				#endif

				bool this_cpu_in_panic(void);

				#ifdef CONFIG_SMP

				extern int __printk_cpu_sync_try_get(void);

				extern void __printk_cpu_sync_wait(void);