fb: Yet another band-aid for fixing lockdep mess

I've still got lockdep warnings even after Alan's patch, and it seems that
yet more band aids are required to paper over similar paths for
unbind_con_driver() and unregister_con_driver().  After this hack, lockdep
warnings are finally gone.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: stable <stable@vger.kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/tty/vt/vt.c

@@ -3134,6 +3134,18 @@ static int con_is_graphics(const struct consw *csw, int first, int last)
  * or 0 on success.
  */
 int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
+{
+	int retval;
+
+	console_lock();
+	retval = do_unbind_con_driver(csw, first, last, deflt);
+	console_unlock();
+	return retval;
+}
+EXPORT_SYMBOL(unbind_con_driver);
+
+/* unlocked version of unbind_con_driver() */
+int do_unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
 {
 	struct module *owner = csw->owner;
 	const struct consw *defcsw = NULL;
@@ -3143,7 +3155,7 @@ int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
 	if (!try_module_get(owner))
 		return -ENODEV;
 
-	console_lock();
+	WARN_CONSOLE_UNLOCKED();
 
 	/* check if driver is registered and if it is unbindable */
 	for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
@@ -3156,10 +3168,8 @@ int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
 		}
 	}
 
-	if (retval) {
+	if (retval)
-		console_unlock();
 		goto err;
-	}
 
 	retval = -ENODEV;
 
@@ -3175,15 +3185,11 @@ int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
 		}
 	}
 
-	if (retval) {
+	if (retval)
-		console_unlock();
 		goto err;
-	}
 
-	if (!con_is_bound(csw)) {
+	if (!con_is_bound(csw))
-		console_unlock();
 		goto err;
-	}
 
 	first = max(first, con_driver->first);
 	last = min(last, con_driver->last);
@@ -3212,13 +3218,12 @@ int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
 
 	/* ignore return value, binding should not fail */
 	do_bind_con_driver(defcsw, first, last, deflt);
-	console_unlock();
 err:
 	module_put(owner);
 	return retval;
 
 }
-EXPORT_SYMBOL(unbind_con_driver);
+EXPORT_SYMBOL_GPL(do_unbind_con_driver);
 
 static int vt_bind(struct con_driver *con)
 {
@@ -3605,9 +3610,18 @@ EXPORT_SYMBOL(register_con_driver);
  */
 int unregister_con_driver(const struct consw *csw)
 {
-	int i, retval = -ENODEV;
+	int retval;
 
 	console_lock();
+	retval = do_unregister_con_driver(csw);
+	console_unlock();
+	return retval;
+}
+EXPORT_SYMBOL(unregister_con_driver);
+
+int do_unregister_con_driver(const struct consw *csw)
+{
+	int i, retval = -ENODEV;
 
 	/* cannot unregister a bound driver */
 	if (con_is_bound(csw))
@@ -3633,10 +3647,9 @@ int unregister_con_driver(const struct consw *csw)
 		}
 	}
 err:
-	console_unlock();
 	return retval;
 }
-EXPORT_SYMBOL(unregister_con_driver);
+EXPORT_SYMBOL_GPL(do_unregister_con_driver);
 
 /*
  *	If we support more console drivers, this function is used

drivers/video/console/fbcon.c

@@ -3004,7 +3004,7 @@ static int fbcon_unbind(void)
 {
 	int ret;
 
-	ret = unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
+	ret = do_unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
 				fbcon_is_default);
 
 	if (!ret)
@@ -3077,7 +3077,7 @@ static int fbcon_fb_unregistered(struct fb_info *info)
 		primary_device = -1;
 
 	if (!num_registered_fb)
-		unregister_con_driver(&fb_con);
+		do_unregister_con_driver(&fb_con);
 
 	return 0;
 }

drivers/video/fbmem.c

@@ -1668,8 +1668,10 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
 
 	if (!lock_fb_info(fb_info))
 		return -ENODEV;
+	console_lock();
 	event.info = fb_info;
 	ret = fb_notifier_call_chain(FB_EVENT_FB_UNBIND, &event);
+	console_unlock();
 	unlock_fb_info(fb_info);
 
 	if (ret)
@@ -1684,7 +1686,9 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
 	num_registered_fb--;
 	fb_cleanup_device(fb_info);
 	event.info = fb_info;
+	console_lock();
 	fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+	console_unlock();
 
 	/* this may free fb info */
 	put_fb_info(fb_info);

include/linux/console.h

@@ -77,6 +77,7 @@ extern const struct consw prom_con;	/* SPARC PROM console */
 int con_is_bound(const struct consw *csw);
 int register_con_driver(const struct consw *csw, int first, int last);
 int unregister_con_driver(const struct consw *csw);
+int do_unregister_con_driver(const struct consw *csw);
 int take_over_console(const struct consw *sw, int first, int last, int deflt);
 int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
 void give_up_console(const struct consw *sw);

include/linux/vt_kern.h

@@ -130,6 +130,8 @@ void vt_event_post(unsigned int event, unsigned int old, unsigned int new);
 int vt_waitactive(int n);
 void change_console(struct vc_data *new_vc);
 void reset_vc(struct vc_data *vc);
+extern int do_unbind_con_driver(const struct consw *csw, int first, int last,
+			     int deflt);
 extern int unbind_con_driver(const struct consw *csw, int first, int last,
 			     int deflt);
 int vty_init(const struct file_operations *console_fops);