Misc: Add possibility to remove misc devices during suspend/resume

Make it possible to unregister a misc device object in a safe way during a
suspend/resume cycle.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/misc.c

@@ -232,8 +232,9 @@ int misc_register(struct miscdevice * misc)
 }
 
 /**
- *	misc_deregister - unregister a miscellaneous device
+ *	__misc_deregister - unregister a miscellaneous device
  *	@misc: device to unregister
+ *	@suspended: to be set if the function is used during suspend/resume
  *
  *	Unregister a miscellaneous device that was previously
  *	successfully registered with misc_register(). Success
@@ -241,7 +242,7 @@ int misc_register(struct miscdevice * misc)
  *	indicates an error.
  */
 
-int misc_deregister(struct miscdevice * misc)
+int __misc_deregister(struct miscdevice *misc, bool suspended)
 {
 	int i = misc->minor;
 
@@ -250,6 +251,10 @@ int misc_deregister(struct miscdevice * misc)
 
 	mutex_lock(&misc_mtx);
 	list_del(&misc->list);
+	if (suspended)
+		destroy_suspended_device(misc_class,
+					MKDEV(MISC_MAJOR, misc->minor));
+	else
 		device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
 	if (i < DYNAMIC_MINORS && i>0) {
 		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
@@ -259,7 +264,7 @@ int misc_deregister(struct miscdevice * misc)
 }
 
 EXPORT_SYMBOL(misc_register);
-EXPORT_SYMBOL(misc_deregister);
+EXPORT_SYMBOL(__misc_deregister);
 
 static int __init misc_init(void)
 {

include/linux/miscdevice.h

@@ -43,7 +43,15 @@ struct miscdevice  {
 };
 
 extern int misc_register(struct miscdevice * misc);
-extern int misc_deregister(struct miscdevice * misc);
+extern int __misc_deregister(struct miscdevice *misc, bool suspended);
+static inline int misc_deregister(struct miscdevice *misc)
+{
+	return __misc_deregister(misc, false);
+}
+static inline int misc_deregister_suspended(struct miscdevice *misc)
+{
+	return __misc_deregister(misc, true);
+}
 
 #define MODULE_ALIAS_MISCDEV(minor)				\
 	MODULE_ALIAS("char-major-" __stringify(MISC_MAJOR)	\