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

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
/*
* 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);
......
......@@ -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
......
#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
......@@ -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
......
#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);
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