This patch introduce some help routines used by next patch. It aims to
ease reviewing, while the next patch will concentrate on algorithm.

Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Grygorii Strashko <grygorii.stras...@ti.com>
Cc: Christoph Hellwig <h...@infradead.org>
Cc: Bjorn Helgaas <helg...@kernel.org>
Cc: Dave Young <dyo...@redhat.com>
Cc: linux-...@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Pingfan Liu <kernelf...@gmail.com>
---
 drivers/base/core.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 36622b5..8113d2c 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -123,6 +123,44 @@ static int device_is_dependent(struct device *dev, void 
*target)
        return ret;
 }
 
+struct pos_info {
+       struct device *pos;
+       struct device *tail;
+};
+
+/* caller takes the devices_kset->list_lock */
+static int descendants_reorder_after_pos(struct device *dev,
+       void *data)
+{
+       struct device *pos;
+       struct pos_info *p = data;
+
+       pos = p->pos;
+       pr_debug("devices_kset: Moving %s after %s\n",
+                dev_name(dev), dev_name(pos));
+       device_for_each_child(dev, p, descendants_reorder_after_pos);
+       /* children at the tail */
+       list_move(&dev->kobj.entry, &pos->kobj.entry);
+       /* record the right boundary of the section */
+       if (p->tail == NULL)
+               p->tail = dev;
+       return 0;
+}
+
+/* iterate over an open section */
+#define list_opensect_for_each_reverse(cur, left, right)       \
+       for (cur = right->prev; cur == left; cur = cur->prev)
+
+static bool is_consumer(struct device *query, struct device *supplier)
+{
+       struct device_link *link;
+       /* todo, lock protection */
+       list_for_each_entry(link, &supplier->links.consumers, s_node)
+               if (link->consumer == query)
+                       return true;
+       return false;
+}
+
 static int device_reorder_to_tail(struct device *dev, void *not_used)
 {
        struct device_link *link;
-- 
2.7.4

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