printk: cpu sync always disable interrupts

The CPU sync functions are a NOP for !CONFIG_SMP. But for
!CONFIG_SMP they still need to disable interrupts in order to
preserve context within the CPU sync sections.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-3-john.ogness@linutronix.de

include/linux/printk.h

@@ -281,9 +281,16 @@ extern int __printk_cpu_sync_try_get(void);
 extern void __printk_cpu_sync_wait(void);
 extern void __printk_cpu_sync_put(void);
 
+#else
+
+#define __printk_cpu_sync_try_get() true
+#define __printk_cpu_sync_wait()
+#define __printk_cpu_sync_put()
+#endif /* CONFIG_SMP */
+
 /**
- * printk_cpu_sync_get_irqsave() - Acquire the printk cpu-reentrant spinning
+ * printk_cpu_sync_get_irqsave() - Disable interrupts and acquire the printk
- *                                 lock and disable interrupts.
+ *                                 cpu-reentrant spinning lock.
  * @flags: Stack-allocated storage for saving local interrupt state,
  *         to be passed to printk_cpu_sync_put_irqrestore().
  *
@@ -322,13 +329,6 @@ extern void __printk_cpu_sync_put(void);
 		local_irq_restore(flags);	\
 	} while (0)
 
-#else
-
-#define printk_cpu_sync_get_irqsave(flags) ((void)flags)
-#define printk_cpu_sync_put_irqrestore(flags) ((void)flags)
-
-#endif /* CONFIG_SMP */
-
 extern int kptr_restrict;
 
 /**