[people/ms/u-boot.git] / lib / list_sort.c

#ifndef __UBOOT__
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#else
#include <linux/compat.h>
#include <common.h>
#include <malloc.h>
#endif
#include <linux/list.h>
#include <linux/list_sort.h>

#define MAX_LIST_LENGTH_BITS 20

/*
 * Returns a list organized in an intermediate format suited
 * to chaining of merge() calls: null-terminated, no reserved or
 * sentinel head node, "prev" links not maintained.
 */
static struct list_head *merge(void *priv,
				int (*cmp)(void *priv, struct list_head *a,
					struct list_head *b),
				struct list_head *a, struct list_head *b)
{
	struct list_head head, *tail = &head;

	while (a && b) {
		/* if equal, take 'a' -- important for sort stability */
		if ((*cmp)(priv, a, b) <= 0) {
			tail->next = a;
			a = a->next;
		} else {
			tail->next = b;
			b = b->next;
		}
		tail = tail->next;
	}
	tail->next = a?:b;
	return head.next;
}

/*
 * Combine final list merge with restoration of standard doubly-linked
 * list structure.  This approach duplicates code from merge(), but
 * runs faster than the tidier alternatives of either a separate final
 * prev-link restoration pass, or maintaining the prev links
 * throughout.
 */
static void merge_and_restore_back_links(void *priv,
				int (*cmp)(void *priv, struct list_head *a,
					struct list_head *b),
				struct list_head *head,
				struct list_head *a, struct list_head *b)
{
	struct list_head *tail = head;

	while (a && b) {
		/* if equal, take 'a' -- important for sort stability */
		if ((*cmp)(priv, a, b) <= 0) {
			tail->next = a;
			a->prev = tail;
			a = a->next;
		} else {
			tail->next = b;
			b->prev = tail;
			b = b->next;
		}
		tail = tail->next;
	}
	tail->next = a ? : b;

	do {
		/*
		 * In worst cases this loop may run many iterations.
		 * Continue callbacks to the client even though no
		 * element comparison is needed, so the client's cmp()
		 * routine can invoke cond_resched() periodically.
		 */
		(*cmp)(priv, tail->next, tail->next);

		tail->next->prev = tail;
		tail = tail->next;
	} while (tail->next);

	tail->next = head;
	head->prev = tail;
}

/**
 * list_sort - sort a list
 * @priv: private data, opaque to list_sort(), passed to @cmp
 * @head: the list to sort
 * @cmp: the elements comparison function
 *
 * This function implements "merge sort", which has O(nlog(n))
 * complexity.
 *
 * The comparison function @cmp must return a negative value if @a
 * should sort before @b, and a positive value if @a should sort after
 * @b. If @a and @b are equivalent, and their original relative
 * ordering is to be preserved, @cmp must return 0.
 */
void list_sort(void *priv, struct list_head *head,
		int (*cmp)(void *priv, struct list_head *a,
			struct list_head *b))
{
	struct list_head *part[MAX_LIST_LENGTH_BITS+1]; /* sorted partial lists
						-- last slot is a sentinel */
	int lev;  /* index into part[] */
	int max_lev = 0;
	struct list_head *list;

	if (list_empty(head))
		return;

	memset(part, 0, sizeof(part));

	head->prev->next = NULL;
	list = head->next;

	while (list) {
		struct list_head *cur = list;
		list = list->next;
		cur->next = NULL;

		for (lev = 0; part[lev]; lev++) {
			cur = merge(priv, cmp, part[lev], cur);
			part[lev] = NULL;
		}
		if (lev > max_lev) {
			if (unlikely(lev >= ARRAY_SIZE(part)-1)) {
				printk_once(KERN_DEBUG "list passed to"
					" list_sort() too long for"
					" efficiency\n");
				lev--;
			}
			max_lev = lev;
		}
		part[lev] = cur;
	}

	for (lev = 0; lev < max_lev; lev++)
		if (part[lev])
			list = merge(priv, cmp, part[lev], list);

	merge_and_restore_back_links(priv, cmp, head, part[max_lev], list);
}
EXPORT_SYMBOL(list_sort);

#ifdef CONFIG_TEST_LIST_SORT

#include <linux/random.h>

/*
 * The pattern of set bits in the list length determines which cases
 * are hit in list_sort().
 */
#define TEST_LIST_LEN (512+128+2) /* not including head */

#define TEST_POISON1 0xDEADBEEF
#define TEST_POISON2 0xA324354C

struct debug_el {
	unsigned int poison1;
	struct list_head list;
	unsigned int poison2;
	int value;
	unsigned serial;
};

/* Array, containing pointers to all elements in the test list */
static struct debug_el **elts __initdata;

static int __init check(struct debug_el *ela, struct debug_el *elb)
{
	if (ela->serial >= TEST_LIST_LEN) {
		printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
				ela->serial);
		return -EINVAL;
	}
	if (elb->serial >= TEST_LIST_LEN) {
		printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
				elb->serial);
		return -EINVAL;
	}
	if (elts[ela->serial] != ela || elts[elb->serial] != elb) {
		printk(KERN_ERR "list_sort_test: error: phantom element\n");
		return -EINVAL;
	}
	if (ela->poison1 != TEST_POISON1 || ela->poison2 != TEST_POISON2) {
		printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
				ela->poison1, ela->poison2);
		return -EINVAL;
	}
	if (elb->poison1 != TEST_POISON1 || elb->poison2 != TEST_POISON2) {
		printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
				elb->poison1, elb->poison2);
		return -EINVAL;
	}
	return 0;
}

static int __init cmp(void *priv, struct list_head *a, struct list_head *b)
{
	struct debug_el *ela, *elb;

	ela = container_of(a, struct debug_el, list);
	elb = container_of(b, struct debug_el, list);

	check(ela, elb);
	return ela->value - elb->value;
}

static int __init list_sort_test(void)
{
	int i, count = 1, err = -EINVAL;
	struct debug_el *el;
	struct list_head *cur, *tmp;
	LIST_HEAD(head);

	printk(KERN_DEBUG "list_sort_test: start testing list_sort()\n");

	elts = kmalloc(sizeof(void *) * TEST_LIST_LEN, GFP_KERNEL);
	if (!elts) {
		printk(KERN_ERR "list_sort_test: error: cannot allocate "
				"memory\n");
		goto exit;
	}

	for (i = 0; i < TEST_LIST_LEN; i++) {
		el = kmalloc(sizeof(*el), GFP_KERNEL);
		if (!el) {
			printk(KERN_ERR "list_sort_test: error: cannot "
					"allocate memory\n");
			goto exit;
		}
		 /* force some equivalencies */
		el->value = prandom_u32() % (TEST_LIST_LEN / 3);
		el->serial = i;
		el->poison1 = TEST_POISON1;
		el->poison2 = TEST_POISON2;
		elts[i] = el;
		list_add_tail(&el->list, &head);
	}

	list_sort(NULL, &head, cmp);

	for (cur = head.next; cur->next != &head; cur = cur->next) {
		struct debug_el *el1;
		int cmp_result;

		if (cur->next->prev != cur) {
			printk(KERN_ERR "list_sort_test: error: list is "
					"corrupted\n");
			goto exit;
		}

		cmp_result = cmp(NULL, cur, cur->next);
		if (cmp_result > 0) {
			printk(KERN_ERR "list_sort_test: error: list is not "
					"sorted\n");
			goto exit;
		}

		el = container_of(cur, struct debug_el, list);
		el1 = container_of(cur->next, struct debug_el, list);
		if (cmp_result == 0 && el->serial >= el1->serial) {
			printk(KERN_ERR "list_sort_test: error: order of "
					"equivalent elements not preserved\n");
			goto exit;
		}

		if (check(el, el1)) {
			printk(KERN_ERR "list_sort_test: error: element check "
					"failed\n");
			goto exit;
		}
		count++;
	}

	if (count != TEST_LIST_LEN) {
		printk(KERN_ERR "list_sort_test: error: bad list length %d",
				count);
		goto exit;
	}

	err = 0;
exit:
	kfree(elts);
	list_for_each_safe(cur, tmp, &head) {
		list_del(cur);
		kfree(container_of(cur, struct debug_el, list));
	}
	return err;
}
module_init(list_sort_test);
#endif /* CONFIG_TEST_LIST_SORT */
Commit	Line	Data
c068d44a HS	1	#ifndef __UBOOT__
	2	#include <linux/kernel.h>
	3	#include <linux/module.h>
	4	#include <linux/slab.h>
	5	#else
	6	#include <linux/compat.h>
	7	#include <common.h>
	8	#include <malloc.h>
	9	#endif
	10	#include <linux/list.h>
	11	#include <linux/list_sort.h>
	12
	13	#define MAX_LIST_LENGTH_BITS 20
	14
	15	/*
	16	* Returns a list organized in an intermediate format suited
	17	* to chaining of merge() calls: null-terminated, no reserved or
	18	* sentinel head node, "prev" links not maintained.
	19	*/
	20	static struct list_head merge(void priv,
	21	int (cmp)(void priv, struct list_head *a,
	22	struct list_head *b),
	23	struct list_head a, struct list_head b)
	24	{
	25	struct list_head head, *tail = &head;
	26
	27	while (a && b) {
	28	/* if equal, take 'a' -- important for sort stability */
	29	if ((*cmp)(priv, a, b) <= 0) {
	30	tail->next = a;
	31	a = a->next;
	32	} else {
	33	tail->next = b;
	34	b = b->next;
	35	}
	36	tail = tail->next;
	37	}
	38	tail->next = a?:b;
	39	return head.next;
	40	}
	41
	42	/*
	43	* Combine final list merge with restoration of standard doubly-linked
	44	* list structure. This approach duplicates code from merge(), but
	45	* runs faster than the tidier alternatives of either a separate final
	46	* prev-link restoration pass, or maintaining the prev links
	47	* throughout.
	48	*/
	49	static void merge_and_restore_back_links(void *priv,
	50	int (cmp)(void priv, struct list_head *a,
	51	struct list_head *b),
	52	struct list_head *head,
	53	struct list_head a, struct list_head b)
	54	{
	55	struct list_head *tail = head;
	56
	57	while (a && b) {
	58	/* if equal, take 'a' -- important for sort stability */
	59	if ((*cmp)(priv, a, b) <= 0) {
	60	tail->next = a;
	61	a->prev = tail;
	62	a = a->next;
	63	} else {
	64	tail->next = b;
65	b->prev = tail;
66	b = b->next;
67	}
68	tail = tail->next;
69	}
70	tail->next = a ? : b;
71
72	do {
73	/*
74	* In worst cases this loop may run many iterations.
75	* Continue callbacks to the client even though no
76	* element comparison is needed, so the client's cmp()
77	* routine can invoke cond_resched() periodically.
78	*/
79	(*cmp)(priv, tail->next, tail->next);
80
81	tail->next->prev = tail;
82	tail = tail->next;
83	} while (tail->next);
84
85	tail->next = head;
86	head->prev = tail;
87	}
88
89	/**
90	* list_sort - sort a list
91	* @priv: private data, opaque to list_sort(), passed to @cmp
92	* @head: the list to sort
93	* @cmp: the elements comparison function
94	*
95	* This function implements "merge sort", which has O(nlog(n))
96	* complexity.
97	*
98	* The comparison function @cmp must return a negative value if @a
99	* should sort before @b, and a positive value if @a should sort after
100	* @b. If @a and @b are equivalent, and their original relative
101	* ordering is to be preserved, @cmp must return 0.
102	*/
103	void list_sort(void priv, struct list_head head,
104	int (cmp)(void priv, struct list_head *a,
105	struct list_head *b))
106	{
107	struct list_head part[MAX_LIST_LENGTH_BITS+1]; / sorted partial lists
108	-- last slot is a sentinel */
109	int lev; /* index into part[] */
110	int max_lev = 0;
111	struct list_head *list;
112
113	if (list_empty(head))
114	return;
115
116	memset(part, 0, sizeof(part));
117
118	head->prev->next = NULL;
119	list = head->next;
120
121	while (list) {
122	struct list_head *cur = list;
123	list = list->next;
124	cur->next = NULL;
125
126	for (lev = 0; part[lev]; lev++) {
127	cur = merge(priv, cmp, part[lev], cur);
128	part[lev] = NULL;
129	}
130	if (lev > max_lev) {
131	if (unlikely(lev >= ARRAY_SIZE(part)-1)) {
132	printk_once(KERN_DEBUG "list passed to"
133	" list_sort() too long for"
134	" efficiency\n");
135	lev--;
136	}
137	max_lev = lev;
138	}
139	part[lev] = cur;
140	}
141
142	for (lev = 0; lev < max_lev; lev++)
143	if (part[lev])
144	list = merge(priv, cmp, part[lev], list);
145
146	merge_and_restore_back_links(priv, cmp, head, part[max_lev], list);
147	}
148	EXPORT_SYMBOL(list_sort);
149
150	#ifdef CONFIG_TEST_LIST_SORT
151
152	#include <linux/random.h>
153
154	/*
155	* The pattern of set bits in the list length determines which cases
156	* are hit in list_sort().
157	*/
158	#define TEST_LIST_LEN (512+128+2) /* not including head */
159
160	#define TEST_POISON1 0xDEADBEEF
161	#define TEST_POISON2 0xA324354C
162
163	struct debug_el {
164	unsigned int poison1;
165	struct list_head list;
166	unsigned int poison2;
167	int value;
168	unsigned serial;
169	};
170
171	/* Array, containing pointers to all elements in the test list */
172	static struct debug_el **elts __initdata;
173
174	static int __init check(struct debug_el ela, struct debug_el elb)
175	{
176	if (ela->serial >= TEST_LIST_LEN) {
177	printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
178	ela->serial);
179	return -EINVAL;
180	}
181	if (elb->serial >= TEST_LIST_LEN) {
182	printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
183	elb->serial);
184	return -EINVAL;
185	}
186	if (elts[ela->serial] != ela \|\| elts[elb->serial] != elb) {
187	printk(KERN_ERR "list_sort_test: error: phantom element\n");
188	return -EINVAL;
189	}
190	if (ela->poison1 != TEST_POISON1 \|\| ela->poison2 != TEST_POISON2) {
191	printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
192	ela->poison1, ela->poison2);
193	return -EINVAL;
194	}
195	if (elb->poison1 != TEST_POISON1 \|\| elb->poison2 != TEST_POISON2) {
196	printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
197	elb->poison1, elb->poison2);
198	return -EINVAL;
199	}
200	return 0;
201	}
202
203	static int __init cmp(void priv, struct list_head a, struct list_head *b)
204	{
205	struct debug_el ela, elb;
206
207	ela = container_of(a, struct debug_el, list);
208	elb = container_of(b, struct debug_el, list);
209
210	check(ela, elb);
211	return ela->value - elb->value;
212	}
213
214	static int __init list_sort_test(void)
215	{
216	int i, count = 1, err = -EINVAL;
217	struct debug_el *el;
218	struct list_head cur, tmp;
219	LIST_HEAD(head);
220
221	printk(KERN_DEBUG "list_sort_test: start testing list_sort()\n");
222
223	elts = kmalloc(sizeof(void ) TEST_LIST_LEN, GFP_KERNEL);
224	if (!elts) {
225	printk(KERN_ERR "list_sort_test: error: cannot allocate "
226	"memory\n");
227	goto exit;
228	}
229
230	for (i = 0; i < TEST_LIST_LEN; i++) {
231	el = kmalloc(sizeof(*el), GFP_KERNEL);
232	if (!el) {
233	printk(KERN_ERR "list_sort_test: error: cannot "
234	"allocate memory\n");
235	goto exit;
236	}
237	/* force some equivalencies */
238	el->value = prandom_u32() % (TEST_LIST_LEN / 3);
239	el->serial = i;
240	el->poison1 = TEST_POISON1;
241	el->poison2 = TEST_POISON2;
242	elts[i] = el;
243	list_add_tail(&el->list, &head);
244	}
245
246	list_sort(NULL, &head, cmp);
247
248	for (cur = head.next; cur->next != &head; cur = cur->next) {
249	struct debug_el *el1;
250	int cmp_result;
251
252	if (cur->next->prev != cur) {
253	printk(KERN_ERR "list_sort_test: error: list is "
254	"corrupted\n");
255	goto exit;
256	}
257
258	cmp_result = cmp(NULL, cur, cur->next);
259	if (cmp_result > 0) {
260	printk(KERN_ERR "list_sort_test: error: list is not "
261	"sorted\n");
262	goto exit;
263	}
264
265	el = container_of(cur, struct debug_el, list);
266	el1 = container_of(cur->next, struct debug_el, list);
267	if (cmp_result == 0 && el->serial >= el1->serial) {
268	printk(KERN_ERR "list_sort_test: error: order of "
269	"equivalent elements not preserved\n");
270	goto exit;
271	}
272
273	if (check(el, el1)) {
274	printk(KERN_ERR "list_sort_test: error: element check "
275	"failed\n");
276	goto exit;
277	}
278	count++;
279	}
280
281	if (count != TEST_LIST_LEN) {
282	printk(KERN_ERR "list_sort_test: error: bad list length %d",
283	count);
284	goto exit;
285	}
286
287	err = 0;
288	exit:
289	kfree(elts);
290	list_for_each_safe(cur, tmp, &head) {
291	list_del(cur);
292	kfree(container_of(cur, struct debug_el, list));
293	}
294	return err;
295	}
296	module_init(list_sort_test);
297	#endif /* CONFIG_TEST_LIST_SORT */