class: add lockdep infrastructure

This adds the infrastructure to properly handle lockdep issues when the
internal class semaphore is changed to a mutex.

Matthew wrote the original patch, and Greg fixed it up to work properly
with the class_create() function.


From: Matthew Wilcox <matthew@wil.cx>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 23 insertions, 2 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index b0556082179..0e1d24c2ed4 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -16,6 +16,7 @@
 #include <linux/kobject.h>
 #include <linux/klist.h>
 #include <linux/list.h>
+#include <linux/lockdep.h>
 #include <linux/compiler.h>
 #include <linux/types.h>
 #include <linux/module.h>
@@ -205,8 +206,18 @@ struct class {
 
 extern struct kobject *sysfs_dev_block_kobj;
 extern struct kobject *sysfs_dev_char_kobj;
-extern int __must_check class_register(struct class *class);
+extern int __must_check __class_register(struct class *class,
+                                         struct lock_class_key *key);
 extern void class_unregister(struct class *class);
+
+/* This is a #define to keep the compiler from merging different
+ * instances of the __key variable */
+#define class_register(class)                   \
+({                                              \
+        static struct lock_class_key __key;     \
+        __class_register(class, &__key);        \
+})
+
 extern int class_for_each_device(struct class *class, struct device *start,
                                  void *data,
                                  int (*fn)(struct device *dev, void *data));
@@ -239,9 +250,19 @@ struct class_interface {
 extern int __must_check class_interface_register(struct class_interface *);
 extern void class_interface_unregister(struct class_interface *);
 
-extern struct class *class_create(struct module *owner, const char *name);
+extern struct class * __must_check __class_create(struct module *owner,
+                                                  const char *name,
+                                                  struct lock_class_key *key);
 extern void class_destroy(struct class *cls);
 
+/* This is a #define to keep the compiler from merging different
+ * instances of the __key variable */
+#define class_create(owner, name)               \
+({                                              \
+        static struct lock_class_key __key;     \
+        __class_create(owner, name, &__key);    \
+})
+
 /*
  * The type of device, "struct device" is embedded in. A class
  * or bus can contain devices of different types