driver-core: use klist for class device list and implement iterator

Iterating over entries using callback usually isn't too fun especially
when the entry being iterated over can't be manipulated freely.  This
patch converts class->p->class_devices to klist and implements class
device iterator so that the users can freely build their own control
structure.  The users are also free to call back into class code
without worrying about locking.

class_for_each_device() and class_find_device() are converted to use
the new iterators, so their users don't have to worry about locking
anymore either.

Note: This depends on klist-dont-iterate-over-deleted-entries patch
because class_intf->add/remove_dev() depends on proper synchronization
with device removal.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 4d8372d135df..246937c9cbc7 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -199,6 +199,11 @@ struct class {
         struct class_private *p;
 };
 
+struct class_dev_iter {
+        struct klist_iter               ki;
+        const struct device_type        *type;
+};
+
 extern struct kobject *sysfs_dev_block_kobj;
 extern struct kobject *sysfs_dev_char_kobj;
 extern int __must_check __class_register(struct class *class,
@@ -213,6 +218,13 @@ extern void class_unregister(struct class *class);
         __class_register(class, &__key);        \
 })
 
+extern void class_dev_iter_init(struct class_dev_iter *iter,
+                                struct class *class,
+                                struct device *start,
+                                const struct device_type *type);
+extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
+extern void class_dev_iter_exit(struct class_dev_iter *iter);
+
 extern int class_for_each_device(struct class *class, struct device *start,
                                  void *data,
                                  int (*fn)(struct device *dev, void *data));
@@ -396,7 +408,7 @@ struct device {
         spinlock_t              devres_lock;
         struct list_head        devres_head;
 
-        struct list_head        node;
+        struct klist_node       knode_class;
         struct class            *class;
         dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
         struct attribute_group  **groups;       /* optional groups */