Commit | Line | Data |
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d0da23b0 AM |
1 | |
2 | #define pr_fmt(fmt) "list_sort_test: " fmt | |
3 | ||
2c761270 DC |
4 | #include <linux/kernel.h> |
5 | #include <linux/module.h> | |
6 | #include <linux/list_sort.h> | |
7 | #include <linux/slab.h> | |
8 | #include <linux/list.h> | |
9 | ||
835cc0c8 DM |
10 | #define MAX_LIST_LENGTH_BITS 20 |
11 | ||
12 | /* | |
13 | * Returns a list organized in an intermediate format suited | |
14 | * to chaining of merge() calls: null-terminated, no reserved or | |
15 | * sentinel head node, "prev" links not maintained. | |
16 | */ | |
17 | static struct list_head *merge(void *priv, | |
18 | int (*cmp)(void *priv, struct list_head *a, | |
19 | struct list_head *b), | |
20 | struct list_head *a, struct list_head *b) | |
21 | { | |
22 | struct list_head head, *tail = &head; | |
23 | ||
24 | while (a && b) { | |
25 | /* if equal, take 'a' -- important for sort stability */ | |
26 | if ((*cmp)(priv, a, b) <= 0) { | |
27 | tail->next = a; | |
28 | a = a->next; | |
29 | } else { | |
30 | tail->next = b; | |
31 | b = b->next; | |
32 | } | |
33 | tail = tail->next; | |
34 | } | |
35 | tail->next = a?:b; | |
36 | return head.next; | |
37 | } | |
38 | ||
39 | /* | |
40 | * Combine final list merge with restoration of standard doubly-linked | |
41 | * list structure. This approach duplicates code from merge(), but | |
42 | * runs faster than the tidier alternatives of either a separate final | |
43 | * prev-link restoration pass, or maintaining the prev links | |
44 | * throughout. | |
45 | */ | |
46 | static void merge_and_restore_back_links(void *priv, | |
47 | int (*cmp)(void *priv, struct list_head *a, | |
48 | struct list_head *b), | |
49 | struct list_head *head, | |
50 | struct list_head *a, struct list_head *b) | |
51 | { | |
52 | struct list_head *tail = head; | |
61b3d6c4 | 53 | u8 count = 0; |
835cc0c8 DM |
54 | |
55 | while (a && b) { | |
56 | /* if equal, take 'a' -- important for sort stability */ | |
57 | if ((*cmp)(priv, a, b) <= 0) { | |
58 | tail->next = a; | |
59 | a->prev = tail; | |
60 | a = a->next; | |
61 | } else { | |
62 | tail->next = b; | |
63 | b->prev = tail; | |
64 | b = b->next; | |
65 | } | |
66 | tail = tail->next; | |
67 | } | |
68 | tail->next = a ? : b; | |
69 | ||
70 | do { | |
71 | /* | |
72 | * In worst cases this loop may run many iterations. | |
73 | * Continue callbacks to the client even though no | |
74 | * element comparison is needed, so the client's cmp() | |
75 | * routine can invoke cond_resched() periodically. | |
76 | */ | |
61b3d6c4 RV |
77 | if (unlikely(!(++count))) |
78 | (*cmp)(priv, tail->next, tail->next); | |
835cc0c8 DM |
79 | |
80 | tail->next->prev = tail; | |
81 | tail = tail->next; | |
82 | } while (tail->next); | |
83 | ||
84 | tail->next = head; | |
85 | head->prev = tail; | |
86 | } | |
87 | ||
2c761270 | 88 | /** |
02b12b7a DM |
89 | * list_sort - sort a list |
90 | * @priv: private data, opaque to list_sort(), passed to @cmp | |
2c761270 DC |
91 | * @head: the list to sort |
92 | * @cmp: the elements comparison function | |
93 | * | |
02b12b7a DM |
94 | * This function implements "merge sort", which has O(nlog(n)) |
95 | * complexity. | |
2c761270 | 96 | * |
02b12b7a DM |
97 | * The comparison function @cmp must return a negative value if @a |
98 | * should sort before @b, and a positive value if @a should sort after | |
99 | * @b. If @a and @b are equivalent, and their original relative | |
100 | * ordering is to be preserved, @cmp must return 0. | |
2c761270 DC |
101 | */ |
102 | void list_sort(void *priv, struct list_head *head, | |
835cc0c8 DM |
103 | int (*cmp)(void *priv, struct list_head *a, |
104 | struct list_head *b)) | |
2c761270 | 105 | { |
835cc0c8 DM |
106 | struct list_head *part[MAX_LIST_LENGTH_BITS+1]; /* sorted partial lists |
107 | -- last slot is a sentinel */ | |
108 | int lev; /* index into part[] */ | |
109 | int max_lev = 0; | |
110 | struct list_head *list; | |
2c761270 DC |
111 | |
112 | if (list_empty(head)) | |
113 | return; | |
114 | ||
835cc0c8 DM |
115 | memset(part, 0, sizeof(part)); |
116 | ||
117 | head->prev->next = NULL; | |
2c761270 | 118 | list = head->next; |
2c761270 | 119 | |
835cc0c8 DM |
120 | while (list) { |
121 | struct list_head *cur = list; | |
122 | list = list->next; | |
123 | cur->next = NULL; | |
124 | ||
125 | for (lev = 0; part[lev]; lev++) { | |
126 | cur = merge(priv, cmp, part[lev], cur); | |
127 | part[lev] = NULL; | |
128 | } | |
129 | if (lev > max_lev) { | |
130 | if (unlikely(lev >= ARRAY_SIZE(part)-1)) { | |
d0da23b0 | 131 | printk_once(KERN_DEBUG "list too long for efficiency\n"); |
835cc0c8 | 132 | lev--; |
2c761270 | 133 | } |
835cc0c8 | 134 | max_lev = lev; |
2c761270 | 135 | } |
835cc0c8 DM |
136 | part[lev] = cur; |
137 | } | |
2c761270 | 138 | |
835cc0c8 DM |
139 | for (lev = 0; lev < max_lev; lev++) |
140 | if (part[lev]) | |
141 | list = merge(priv, cmp, part[lev], list); | |
2c761270 | 142 | |
835cc0c8 DM |
143 | merge_and_restore_back_links(priv, cmp, head, part[max_lev], list); |
144 | } | |
145 | EXPORT_SYMBOL(list_sort); | |
2c761270 | 146 | |
6d411e6c | 147 | #ifdef CONFIG_TEST_LIST_SORT |
eeee9ebb AB |
148 | |
149 | #include <linux/random.h> | |
150 | ||
041b78f2 AB |
151 | /* |
152 | * The pattern of set bits in the list length determines which cases | |
153 | * are hit in list_sort(). | |
154 | */ | |
155 | #define TEST_LIST_LEN (512+128+2) /* not including head */ | |
156 | ||
157 | #define TEST_POISON1 0xDEADBEEF | |
158 | #define TEST_POISON2 0xA324354C | |
159 | ||
835cc0c8 | 160 | struct debug_el { |
041b78f2 | 161 | unsigned int poison1; |
eeee9ebb | 162 | struct list_head list; |
041b78f2 | 163 | unsigned int poison2; |
835cc0c8 DM |
164 | int value; |
165 | unsigned serial; | |
166 | }; | |
2c761270 | 167 | |
041b78f2 AB |
168 | /* Array, containing pointers to all elements in the test list */ |
169 | static struct debug_el **elts __initdata; | |
170 | ||
171 | static int __init check(struct debug_el *ela, struct debug_el *elb) | |
835cc0c8 | 172 | { |
041b78f2 | 173 | if (ela->serial >= TEST_LIST_LEN) { |
d0da23b0 | 174 | pr_err("error: incorrect serial %d\n", ela->serial); |
041b78f2 AB |
175 | return -EINVAL; |
176 | } | |
177 | if (elb->serial >= TEST_LIST_LEN) { | |
d0da23b0 | 178 | pr_err("error: incorrect serial %d\n", elb->serial); |
041b78f2 AB |
179 | return -EINVAL; |
180 | } | |
181 | if (elts[ela->serial] != ela || elts[elb->serial] != elb) { | |
d0da23b0 | 182 | pr_err("error: phantom element\n"); |
041b78f2 AB |
183 | return -EINVAL; |
184 | } | |
185 | if (ela->poison1 != TEST_POISON1 || ela->poison2 != TEST_POISON2) { | |
d0da23b0 AM |
186 | pr_err("error: bad poison: %#x/%#x\n", |
187 | ela->poison1, ela->poison2); | |
041b78f2 AB |
188 | return -EINVAL; |
189 | } | |
190 | if (elb->poison1 != TEST_POISON1 || elb->poison2 != TEST_POISON2) { | |
d0da23b0 AM |
191 | pr_err("error: bad poison: %#x/%#x\n", |
192 | elb->poison1, elb->poison2); | |
041b78f2 AB |
193 | return -EINVAL; |
194 | } | |
195 | return 0; | |
2c761270 DC |
196 | } |
197 | ||
041b78f2 AB |
198 | static int __init cmp(void *priv, struct list_head *a, struct list_head *b) |
199 | { | |
200 | struct debug_el *ela, *elb; | |
201 | ||
202 | ela = container_of(a, struct debug_el, list); | |
203 | elb = container_of(b, struct debug_el, list); | |
204 | ||
205 | check(ela, elb); | |
206 | return ela->value - elb->value; | |
207 | } | |
835cc0c8 DM |
208 | |
209 | static int __init list_sort_test(void) | |
210 | { | |
27d555d1 | 211 | int i, count = 1, err = -ENOMEM; |
f3dc0e38 | 212 | struct debug_el *el; |
69412303 | 213 | struct list_head *cur; |
f3dc0e38 | 214 | LIST_HEAD(head); |
835cc0c8 | 215 | |
d0da23b0 | 216 | pr_debug("start testing list_sort()\n"); |
835cc0c8 | 217 | |
69412303 | 218 | elts = kcalloc(TEST_LIST_LEN, sizeof(*elts), GFP_KERNEL); |
041b78f2 | 219 | if (!elts) { |
d0da23b0 | 220 | pr_err("error: cannot allocate memory\n"); |
69412303 | 221 | return err; |
041b78f2 AB |
222 | } |
223 | ||
eeee9ebb | 224 | for (i = 0; i < TEST_LIST_LEN; i++) { |
f3dc0e38 AB |
225 | el = kmalloc(sizeof(*el), GFP_KERNEL); |
226 | if (!el) { | |
d0da23b0 | 227 | pr_err("error: cannot allocate memory\n"); |
f3dc0e38 AB |
228 | goto exit; |
229 | } | |
835cc0c8 | 230 | /* force some equivalencies */ |
f39fee5f | 231 | el->value = prandom_u32() % (TEST_LIST_LEN / 3); |
835cc0c8 | 232 | el->serial = i; |
041b78f2 AB |
233 | el->poison1 = TEST_POISON1; |
234 | el->poison2 = TEST_POISON2; | |
235 | elts[i] = el; | |
f3dc0e38 | 236 | list_add_tail(&el->list, &head); |
835cc0c8 | 237 | } |
835cc0c8 | 238 | |
f3dc0e38 AB |
239 | list_sort(NULL, &head, cmp); |
240 | ||
27d555d1 | 241 | err = -EINVAL; |
f3dc0e38 AB |
242 | for (cur = head.next; cur->next != &head; cur = cur->next) { |
243 | struct debug_el *el1; | |
244 | int cmp_result; | |
835cc0c8 | 245 | |
835cc0c8 | 246 | if (cur->next->prev != cur) { |
d0da23b0 | 247 | pr_err("error: list is corrupted\n"); |
f3dc0e38 AB |
248 | goto exit; |
249 | } | |
250 | ||
251 | cmp_result = cmp(NULL, cur, cur->next); | |
252 | if (cmp_result > 0) { | |
d0da23b0 | 253 | pr_err("error: list is not sorted\n"); |
f3dc0e38 AB |
254 | goto exit; |
255 | } | |
256 | ||
257 | el = container_of(cur, struct debug_el, list); | |
258 | el1 = container_of(cur->next, struct debug_el, list); | |
259 | if (cmp_result == 0 && el->serial >= el1->serial) { | |
d0da23b0 AM |
260 | pr_err("error: order of equivalent elements not " |
261 | "preserved\n"); | |
f3dc0e38 | 262 | goto exit; |
835cc0c8 | 263 | } |
041b78f2 AB |
264 | |
265 | if (check(el, el1)) { | |
d0da23b0 | 266 | pr_err("error: element check failed\n"); |
041b78f2 AB |
267 | goto exit; |
268 | } | |
835cc0c8 DM |
269 | count++; |
270 | } | |
9d418dcc | 271 | if (head.prev != cur) { |
d0da23b0 | 272 | pr_err("error: list is corrupted\n"); |
9d418dcc RV |
273 | goto exit; |
274 | } | |
275 | ||
f3dc0e38 | 276 | |
eeee9ebb | 277 | if (count != TEST_LIST_LEN) { |
d0da23b0 | 278 | pr_err("error: bad list length %d", count); |
f3dc0e38 AB |
279 | goto exit; |
280 | } | |
281 | ||
282 | err = 0; | |
283 | exit: | |
69412303 RV |
284 | for (i = 0; i < TEST_LIST_LEN; i++) |
285 | kfree(elts[i]); | |
041b78f2 | 286 | kfree(elts); |
f3dc0e38 | 287 | return err; |
835cc0c8 DM |
288 | } |
289 | module_init(list_sort_test); | |
6d411e6c | 290 | #endif /* CONFIG_TEST_LIST_SORT */ |