[PATCH v4 5/6] console: Introduce ->exit() callback

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

Some consoles might require special operations on unregistering.
For instance, serial console, when registered in the kernel,
keeps power on for entire time, until it gets unregistered.
Example of use:

	->setup(console):
		pm_runtime_get(...);

	->exit(console):
		pm_runtime_put(...);

For such cases to have a balance we would provide ->exit() callback.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v4: Don't rely on CON_ENABLED at all (Sergey, Petr), update commit message (Petr)
 include/linux/console.h | 1 +
 kernel/printk/printk.c  | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/include/linux/console.h b/include/linux/console.h
index f33016b3a401..54759ad0c36b 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -148,6 +148,7 @@ struct console {
 	struct tty_driver *(*device)(struct console *, int *);
 	void	(*unblank)(void);
 	int	(*setup)(struct console *, char *);
+	void	(*exit)(struct console *);
 	int	(*match)(struct console *, char *name, int idx, char *options);
 	short	flags;
 	short	index;
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 932345e6cd71..0117d4d92a8e 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2850,6 +2850,10 @@ int unregister_console(struct console *console)
 	console->flags &= ~CON_ENABLED;
 	console_unlock();
 	console_sysfs_notify();
+
+	if (!res && console->exit)
+		console->exit(console);
+
 	return res;
 }
 EXPORT_SYMBOL(unregister_console);
-- 
2.24.1