1 files changed, 32 insertions, 12 deletions

diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
index 348443bdb23b..789d12128c24 100644
--- a/drivers/misc/enclosure.c
+++ b/drivers/misc/enclosure.c
@@ -33,24 +33,44 @@ static DEFINE_MUTEX(container_list_lock);
 static struct class enclosure_class;
 
 /**
- * enclosure_find - find an enclosure given a device
- * @dev:        the device to find for
+ * enclosure_find - find an enclosure given a parent device
+ * @dev:        the parent to match against
+ * @start:      Optional enclosure device to start from (NULL if none)
  *
- * Looks through the list of registered enclosures to see
- * if it can find a match for a device.  Returns NULL if no
- * enclosure is found. Obtains a reference to the enclosure class
- * device which must be released with device_put().
+ * Looks through the list of registered enclosures to find all those
+ * with @dev as a parent.  Returns NULL if no enclosure is
+ * found. @start can be used as a starting point to obtain multiple
+ * enclosures per parent (should begin with NULL and then be set to
+ * each returned enclosure device). Obtains a reference to the
+ * enclosure class device which must be released with device_put().
+ * If @start is not NULL, a reference must be taken on it which is
+ * released before returning (this allows a loop through all
+ * enclosures to exit with only the reference on the enclosure of
+ * interest held).  Note that the @dev may correspond to the actual
+ * device housing the enclosure, in which case no iteration via @start
+ * is required.
  */
-struct enclosure_device *enclosure_find(struct device *dev)
+struct enclosure_device *enclosure_find(struct device *dev,
+                                        struct enclosure_device *start)
 {
         struct enclosure_device *edev;
 
         mutex_lock(&container_list_lock);
-        list_for_each_entry(edev, &container_list, node) {
-                if (edev->edev.parent == dev) {
-                        get_device(&edev->edev);
-                        mutex_unlock(&container_list_lock);
-                        return edev;
+        edev = list_prepare_entry(start, &container_list, node);
+        if (start)
+                put_device(&start->edev);
+
+        list_for_each_entry_continue(edev, &container_list, node) {
+                struct device *parent = edev->edev.parent;
+                /* parent might not be immediate, so iterate up to
+                 * the root of the tree if necessary */
+                while (parent) {
+                        if (parent == dev) {
+                                get_device(&edev->edev);
+                                mutex_unlock(&container_list_lock);
+                                return edev;
+                        }
+                        parent = parent->parent;
                 }
         }
         mutex_unlock(&container_list_lock);