lib: Introduce generic list_sort function

There are two copies of list_sort() in the tree already, one in the DRM
code, another in ubifs.  Now XFS needs this as well.  Create a generic
list_sort() function from the ubifs version and convert existing users
to it so we don't end up with yet another copy in the tree.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Artem Bityutskiy <dedekind@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 86 deletions

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 6d81a02463a3..76d63394c776 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1,9 +1,4 @@
 /*
- * The list_sort function is (presumably) licensed under the GPL (see the
- * top level "COPYING" file for details).
- *
- * The remainder of this file is:
- *
  * Copyright © 1997-2003 by The XFree86 Project, Inc.
  * Copyright © 2007 Dave Airlie
  * Copyright © 2007-2008 Intel Corporation
@@ -36,6 +31,7 @@
  */
 
 #include <linux/list.h>
+#include <linux/list_sort.h>
 #include "drmP.h"
 #include "drm.h"
 #include "drm_crtc.h"
@@ -855,6 +851,7 @@ EXPORT_SYMBOL(drm_mode_prune_invalid);
 
 /**
  * drm_mode_compare - compare modes for favorability
+ * @priv: unused
  * @lh_a: list_head for first mode
  * @lh_b: list_head for second mode
  *
@@ -868,7 +865,7 @@ EXPORT_SYMBOL(drm_mode_prune_invalid);
  * Negative if @lh_a is better than @lh_b, zero if they're equivalent, or
  * positive if @lh_b is better than @lh_a.
  */
-static int drm_mode_compare(struct list_head *lh_a, struct list_head *lh_b)
+static int drm_mode_compare(void *priv, struct list_head *lh_a, struct list_head *lh_b)
 {
 	struct drm_display_mode *a = list_entry(lh_a, struct drm_display_mode, head);
 	struct drm_display_mode *b = list_entry(lh_b, struct drm_display_mode, head);
@@ -885,85 +882,6 @@ static int drm_mode_compare(struct list_head *lh_a, struct list_head *lh_b)
 	return diff;
 }
 
-/* FIXME: what we don't have a list sort function? */
-/* list sort from Mark J Roberts (mjr@znex.org) */
-void list_sort(struct list_head *head,
-	       int (*cmp)(struct list_head *a, struct list_head *b))
-{
-	struct list_head *p, *q, *e, *list, *tail, *oldhead;
-	int insize, nmerges, psize, qsize, i;
-
-	list = head->next;
-	list_del(head);
-	insize = 1;
-	for (;;) {
-		p = oldhead = list;
-		list = tail = NULL;
-		nmerges = 0;
-
-		while (p) {
-			nmerges++;
-			q = p;
-			psize = 0;
-			for (i = 0; i < insize; i++) {
-				psize++;
-				q = q->next == oldhead ? NULL : q->next;
-				if (!q)
-					break;
-			}
-
-			qsize = insize;
-			while (psize > 0 || (qsize > 0 && q)) {
-				if (!psize) {
-					e = q;
-					q = q->next;
-					qsize--;
-					if (q == oldhead)
-						q = NULL;
-				} else if (!qsize || !q) {
-					e = p;
-					p = p->next;
-					psize--;
-					if (p == oldhead)
-						p = NULL;
-				} else if (cmp(p, q) <= 0) {
-					e = p;
-					p = p->next;
-					psize--;
-					if (p == oldhead)
-						p = NULL;
-				} else {
-					e = q;
-					q = q->next;
-					qsize--;
-					if (q == oldhead)
-						q = NULL;
-				}
-				if (tail)
-					tail->next = e;
-				else
-					list = e;
-				e->prev = tail;
-				tail = e;
-			}
-			p = q;
-		}
-
-		tail->next = list;
-		list->prev = tail;
-
-		if (nmerges <= 1)
-			break;
-
-		insize *= 2;
-	}
-
-	head->next = list;
-	head->prev = list->prev;
-	list->prev->next = head;
-	list->prev = head;
-}
-
 /**
  * drm_mode_sort - sort mode list
  * @mode_list: list to sort
@@ -975,7 +893,7 @@ void list_sort(struct list_head *head,
  */
 void drm_mode_sort(struct list_head *mode_list)
 {
-	list_sort(mode_list, drm_mode_compare);
+	list_sort(NULL, mode_list, drm_mode_compare);
 }
 EXPORT_SYMBOL(drm_mode_sort);