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

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Date:   Thu, 30 Jan 2020 17:25:57 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v4 5/6] console: Introduce ->exit() callback

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@...ux.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