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 */
merge(void * priv,int (* cmp)(void * priv,struct list_head * a,struct list_head * b),struct list_head * a,struct list_head * b)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 */
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)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 */
list_sort(void * priv,struct list_head * head,int (* cmp)(void * priv,struct list_head * a,struct list_head * b))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
check(struct debug_el * ela,struct debug_el * elb)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
cmp(void * priv,struct list_head * a,struct list_head * b)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
list_sort_test(void)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 */
298