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Commit 2c761270 authored by Dave Chinner's avatar Dave Chinner Committed by Linus Torvalds
Browse files

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: default avatarDave Chinner <david@fromorbit.com>
Acked-by: default avatarDave Airlie <airlied@redhat.com>
Acked-by: default avatarArtem Bityutskiy <dedekind@infradead.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dbf004d7

drivers/gpu/drm/drm_modes.c

+4 −86
Original line number Diff line number Diff line 
/*

 * 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);

fs/ubifs/gc.c

+1 −95
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
 */



#include <linux/pagemap.h>

#include <linux/list_sort.h>

#include "ubifs.h"



/*
@@ -107,101 +108,6 @@ static int switch_gc_head(struct ubifs_info *c) 
	return err;

}



/**

 * list_sort - sort a list.

 * @priv: private data, passed to @cmp

 * @head: the list to sort

 * @cmp: the elements comparison function

 *

 * This function has been implemented by Mark J Roberts <mjr@znex.org>. It

 * implements "merge sort" which has O(nlog(n)) complexity. The list is sorted

 * in ascending order.

 *

 * The comparison function @cmp is supposed to return a negative value if @a is

 * than @b, and a positive value if @a is greater than @b. If @a and @b are

 * equivalent, then it does not matter what this function returns.

 */

static void list_sort(void *priv, struct list_head *head,

		      int (*cmp)(void *priv, struct list_head *a,

				 struct list_head *b))

{

	struct list_head *p, *q, *e, *list, *tail, *oldhead;

	int insize, nmerges, psize, qsize, i;



	if (list_empty(head))

		return;



	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(priv, 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;

}



/**

 * data_nodes_cmp - compare 2 data nodes.

 * @priv: UBIFS file-system description object

include/linux/list_sort.h

0 → 100644
+11 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_LIST_SORT_H

#define _LINUX_LIST_SORT_H



#include <linux/types.h>



struct list_head;



void list_sort(void *priv, struct list_head *head,

	       int (*cmp)(void *priv, struct list_head *a,

			  struct list_head *b));

#endif

lib/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ lib-y += kobject.o kref.o klist.o 


obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \

	 bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \

	 string_helpers.o gcd.o

	 string_helpers.o gcd.o list_sort.o



ifeq ($(CONFIG_DEBUG_KOBJECT),y)

CFLAGS_kobject.o += -DDEBUG

lib/list_sort.c

0 → 100644
+102 −0
Original line number Diff line number Diff line 
#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/list_sort.h>

#include <linux/slab.h>

#include <linux/list.h>



/**

 * list_sort - sort a list.

 * @priv: private data, passed to @cmp

 * @head: the list to sort

 * @cmp: the elements comparison function

 *

 * This function has been implemented by Mark J Roberts <mjr@znex.org>. It

 * implements "merge sort" which has O(nlog(n)) complexity. The list is sorted

 * in ascending order.

 *

 * The comparison function @cmp is supposed to return a negative value if @a is

 * less than @b, and a positive value if @a is greater than @b. If @a and @b

 * are equivalent, then it does not matter what this function returns.

 */

void list_sort(void *priv, struct list_head *head,

	       int (*cmp)(void *priv, struct list_head *a,

			  struct list_head *b))

{

	struct list_head *p, *q, *e, *list, *tail, *oldhead;

	int insize, nmerges, psize, qsize, i;



	if (list_empty(head))

		return;



	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(priv, 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;

}



EXPORT_SYMBOL(list_sort);