Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 1 | #include <linux/kernel.h> |
| 2 | #include <linux/module.h> |
| 3 | #include <linux/list_sort.h> |
| 4 | #include <linux/slab.h> |
| 5 | #include <linux/list.h> |
| 6 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 7 | #define MAX_LIST_LENGTH_BITS 20 |
| 8 | |
| 9 | /* |
| 10 | * Returns a list organized in an intermediate format suited |
| 11 | * to chaining of merge() calls: null-terminated, no reserved or |
| 12 | * sentinel head node, "prev" links not maintained. |
| 13 | */ |
| 14 | static struct list_head *merge(void *priv, |
| 15 | int (*cmp)(void *priv, struct list_head *a, |
| 16 | struct list_head *b), |
| 17 | struct list_head *a, struct list_head *b) |
| 18 | { |
| 19 | struct list_head head, *tail = &head; |
| 20 | |
| 21 | while (a && b) { |
| 22 | /* if equal, take 'a' -- important for sort stability */ |
| 23 | if ((*cmp)(priv, a, b) <= 0) { |
| 24 | tail->next = a; |
| 25 | a = a->next; |
| 26 | } else { |
| 27 | tail->next = b; |
| 28 | b = b->next; |
| 29 | } |
| 30 | tail = tail->next; |
| 31 | } |
| 32 | tail->next = a?:b; |
| 33 | return head.next; |
| 34 | } |
| 35 | |
| 36 | /* |
| 37 | * Combine final list merge with restoration of standard doubly-linked |
| 38 | * list structure. This approach duplicates code from merge(), but |
| 39 | * runs faster than the tidier alternatives of either a separate final |
| 40 | * prev-link restoration pass, or maintaining the prev links |
| 41 | * throughout. |
| 42 | */ |
| 43 | static void merge_and_restore_back_links(void *priv, |
| 44 | int (*cmp)(void *priv, struct list_head *a, |
| 45 | struct list_head *b), |
| 46 | struct list_head *head, |
| 47 | struct list_head *a, struct list_head *b) |
| 48 | { |
| 49 | struct list_head *tail = head; |
| 50 | |
| 51 | while (a && b) { |
| 52 | /* if equal, take 'a' -- important for sort stability */ |
| 53 | if ((*cmp)(priv, a, b) <= 0) { |
| 54 | tail->next = a; |
| 55 | a->prev = tail; |
| 56 | a = a->next; |
| 57 | } else { |
| 58 | tail->next = b; |
| 59 | b->prev = tail; |
| 60 | b = b->next; |
| 61 | } |
| 62 | tail = tail->next; |
| 63 | } |
| 64 | tail->next = a ? : b; |
| 65 | |
| 66 | do { |
| 67 | /* |
| 68 | * In worst cases this loop may run many iterations. |
| 69 | * Continue callbacks to the client even though no |
| 70 | * element comparison is needed, so the client's cmp() |
| 71 | * routine can invoke cond_resched() periodically. |
| 72 | */ |
Don Mullis | f015ac3 | 2010-09-30 15:15:32 -0700 | [diff] [blame] | 73 | (*cmp)(priv, tail->next, tail->next); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 74 | |
| 75 | tail->next->prev = tail; |
| 76 | tail = tail->next; |
| 77 | } while (tail->next); |
| 78 | |
| 79 | tail->next = head; |
| 80 | head->prev = tail; |
| 81 | } |
| 82 | |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 83 | /** |
Don Mullis | 02b12b7 | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 84 | * list_sort - sort a list |
| 85 | * @priv: private data, opaque to list_sort(), passed to @cmp |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 86 | * @head: the list to sort |
| 87 | * @cmp: the elements comparison function |
| 88 | * |
Don Mullis | 02b12b7 | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 89 | * This function implements "merge sort", which has O(nlog(n)) |
| 90 | * complexity. |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 91 | * |
Don Mullis | 02b12b7 | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 92 | * The comparison function @cmp must return a negative value if @a |
| 93 | * should sort before @b, and a positive value if @a should sort after |
| 94 | * @b. If @a and @b are equivalent, and their original relative |
| 95 | * ordering is to be preserved, @cmp must return 0. |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 96 | */ |
| 97 | void list_sort(void *priv, struct list_head *head, |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 98 | int (*cmp)(void *priv, struct list_head *a, |
| 99 | struct list_head *b)) |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 100 | { |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 101 | struct list_head *part[MAX_LIST_LENGTH_BITS+1]; /* sorted partial lists |
| 102 | -- last slot is a sentinel */ |
| 103 | int lev; /* index into part[] */ |
| 104 | int max_lev = 0; |
| 105 | struct list_head *list; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 106 | |
| 107 | if (list_empty(head)) |
| 108 | return; |
| 109 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 110 | memset(part, 0, sizeof(part)); |
| 111 | |
| 112 | head->prev->next = NULL; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 113 | list = head->next; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 114 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 115 | while (list) { |
| 116 | struct list_head *cur = list; |
| 117 | list = list->next; |
| 118 | cur->next = NULL; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 119 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 120 | for (lev = 0; part[lev]; lev++) { |
| 121 | cur = merge(priv, cmp, part[lev], cur); |
| 122 | part[lev] = NULL; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 123 | } |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 124 | if (lev > max_lev) { |
| 125 | if (unlikely(lev >= ARRAY_SIZE(part)-1)) { |
| 126 | printk_once(KERN_DEBUG "list passed to" |
| 127 | " list_sort() too long for" |
| 128 | " efficiency\n"); |
| 129 | lev--; |
| 130 | } |
| 131 | max_lev = lev; |
| 132 | } |
| 133 | part[lev] = cur; |
Dave Chinner | 2c76127 | 2010-01-12 17:39:16 +1100 | [diff] [blame] | 134 | } |
| 135 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 136 | for (lev = 0; lev < max_lev; lev++) |
| 137 | if (part[lev]) |
| 138 | list = merge(priv, cmp, part[lev], list); |
| 139 | |
| 140 | merge_and_restore_back_links(priv, cmp, head, part[max_lev], list); |
| 141 | } |
| 142 | EXPORT_SYMBOL(list_sort); |
| 143 | |
Artem Bityutskiy | 6d411e6 | 2010-10-26 14:23:05 -0700 | [diff] [blame] | 144 | #ifdef CONFIG_TEST_LIST_SORT |
Artem Bityutskiy | eeee9eb | 2010-10-26 14:23:06 -0700 | [diff] [blame] | 145 | |
| 146 | #include <linux/random.h> |
| 147 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 148 | /* |
| 149 | * The pattern of set bits in the list length determines which cases |
| 150 | * are hit in list_sort(). |
| 151 | */ |
Artem Bityutskiy | eeee9eb | 2010-10-26 14:23:06 -0700 | [diff] [blame] | 152 | #define TEST_LIST_LEN (512+128+2) /* not including head */ |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 153 | |
Artem Bityutskiy | 041b78f | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 154 | #define TEST_POISON1 0xDEADBEEF |
| 155 | #define TEST_POISON2 0xA324354C |
| 156 | |
| 157 | struct debug_el { |
| 158 | unsigned int poison1; |
| 159 | struct list_head list; |
| 160 | unsigned int poison2; |
| 161 | int value; |
| 162 | unsigned serial; |
| 163 | }; |
| 164 | |
| 165 | /* Array, containing pointers to all elements in the test list */ |
| 166 | static struct debug_el **elts __initdata; |
| 167 | |
| 168 | static int __init check(struct debug_el *ela, struct debug_el *elb) |
| 169 | { |
| 170 | if (ela->serial >= TEST_LIST_LEN) { |
| 171 | printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n", |
| 172 | ela->serial); |
| 173 | return -EINVAL; |
| 174 | } |
| 175 | if (elb->serial >= TEST_LIST_LEN) { |
| 176 | printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n", |
| 177 | elb->serial); |
| 178 | return -EINVAL; |
| 179 | } |
| 180 | if (elts[ela->serial] != ela || elts[elb->serial] != elb) { |
| 181 | printk(KERN_ERR "list_sort_test: error: phantom element\n"); |
| 182 | return -EINVAL; |
| 183 | } |
| 184 | if (ela->poison1 != TEST_POISON1 || ela->poison2 != TEST_POISON2) { |
| 185 | printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n", |
| 186 | ela->poison1, ela->poison2); |
| 187 | return -EINVAL; |
| 188 | } |
| 189 | if (elb->poison1 != TEST_POISON1 || elb->poison2 != TEST_POISON2) { |
| 190 | printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n", |
| 191 | elb->poison1, elb->poison2); |
| 192 | return -EINVAL; |
| 193 | } |
| 194 | return 0; |
| 195 | } |
| 196 | |
| 197 | static int __init cmp(void *priv, struct list_head *a, struct list_head *b) |
| 198 | { |
| 199 | struct debug_el *ela, *elb; |
| 200 | |
| 201 | ela = container_of(a, struct debug_el, list); |
| 202 | elb = container_of(b, struct debug_el, list); |
| 203 | |
| 204 | check(ela, elb); |
| 205 | return ela->value - elb->value; |
| 206 | } |
| 207 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 208 | static int __init list_sort_test(void) |
| 209 | { |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 210 | int i, count = 1, err = -EINVAL; |
| 211 | struct debug_el *el; |
| 212 | struct list_head *cur, *tmp; |
| 213 | LIST_HEAD(head); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 214 | |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 215 | printk(KERN_DEBUG "list_sort_test: start testing list_sort()\n"); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 216 | |
Artem Bityutskiy | 041b78f | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 217 | elts = kmalloc(sizeof(void *) * TEST_LIST_LEN, GFP_KERNEL); |
| 218 | if (!elts) { |
| 219 | printk(KERN_ERR "list_sort_test: error: cannot allocate " |
| 220 | "memory\n"); |
| 221 | goto exit; |
| 222 | } |
| 223 | |
Artem Bityutskiy | eeee9eb | 2010-10-26 14:23:06 -0700 | [diff] [blame] | 224 | for (i = 0; i < TEST_LIST_LEN; i++) { |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 225 | el = kmalloc(sizeof(*el), GFP_KERNEL); |
| 226 | if (!el) { |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 227 | printk(KERN_ERR "list_sort_test: error: cannot " |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 228 | "allocate memory\n"); |
| 229 | goto exit; |
| 230 | } |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 231 | /* force some equivalencies */ |
Artem Bityutskiy | eeee9eb | 2010-10-26 14:23:06 -0700 | [diff] [blame] | 232 | el->value = random32() % (TEST_LIST_LEN/3); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 233 | el->serial = i; |
Artem Bityutskiy | 041b78f | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 234 | el->poison1 = TEST_POISON1; |
| 235 | el->poison2 = TEST_POISON2; |
| 236 | elts[i] = el; |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 237 | list_add_tail(&el->list, &head); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 238 | } |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 239 | |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 240 | list_sort(NULL, &head, cmp); |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 241 | |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 242 | for (cur = head.next; cur->next != &head; cur = cur->next) { |
| 243 | struct debug_el *el1; |
| 244 | int cmp_result; |
| 245 | |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 246 | if (cur->next->prev != cur) { |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 247 | printk(KERN_ERR "list_sort_test: error: list is " |
| 248 | "corrupted\n"); |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 249 | goto exit; |
| 250 | } |
| 251 | |
| 252 | cmp_result = cmp(NULL, cur, cur->next); |
| 253 | if (cmp_result > 0) { |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 254 | printk(KERN_ERR "list_sort_test: error: list is not " |
| 255 | "sorted\n"); |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 256 | goto exit; |
| 257 | } |
| 258 | |
| 259 | el = container_of(cur, struct debug_el, list); |
| 260 | el1 = container_of(cur->next, struct debug_el, list); |
| 261 | if (cmp_result == 0 && el->serial >= el1->serial) { |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 262 | printk(KERN_ERR "list_sort_test: error: order of " |
| 263 | "equivalent elements not preserved\n"); |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 264 | goto exit; |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 265 | } |
Artem Bityutskiy | 041b78f | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 266 | |
| 267 | if (check(el, el1)) { |
| 268 | printk(KERN_ERR "list_sort_test: error: element check " |
| 269 | "failed\n"); |
| 270 | goto exit; |
| 271 | } |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 272 | count++; |
| 273 | } |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 274 | |
Artem Bityutskiy | eeee9eb | 2010-10-26 14:23:06 -0700 | [diff] [blame] | 275 | if (count != TEST_LIST_LEN) { |
Artem Bityutskiy | 014afa9 | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 276 | printk(KERN_ERR "list_sort_test: error: bad list length %d", |
| 277 | count); |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 278 | goto exit; |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 279 | } |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 280 | |
| 281 | err = 0; |
| 282 | exit: |
Artem Bityutskiy | 041b78f | 2010-10-26 14:23:08 -0700 | [diff] [blame] | 283 | kfree(elts); |
Artem Bityutskiy | f3dc0e3 | 2010-10-26 14:23:07 -0700 | [diff] [blame] | 284 | list_for_each_safe(cur, tmp, &head) { |
| 285 | list_del(cur); |
| 286 | kfree(container_of(cur, struct debug_el, list)); |
| 287 | } |
| 288 | return err; |
Don Mullis | 835cc0c | 2010-03-05 13:43:15 -0800 | [diff] [blame] | 289 | } |
| 290 | module_init(list_sort_test); |
Artem Bityutskiy | 6d411e6 | 2010-10-26 14:23:05 -0700 | [diff] [blame] | 291 | #endif /* CONFIG_TEST_LIST_SORT */ |