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c1d7c514 | 1 | // SPDX-License-Identifier: GPL-2.0 |
da5c8135 AJ |
2 | /* |
3 | * Copyright (C) 2011 STRATO AG | |
4 | * written by Arne Jansen <sensille@gmx.net> | |
da5c8135 AJ |
5 | */ |
6 | ||
7 | #include <linux/slab.h> | |
9b569ea0 | 8 | #include "messages.h" |
da5c8135 AJ |
9 | #include "ulist.h" |
10 | ||
11 | /* | |
12 | * ulist is a generic data structure to hold a collection of unique u64 | |
13 | * values. The only operations it supports is adding to the list and | |
14 | * enumerating it. | |
15 | * It is possible to store an auxiliary value along with the key. | |
16 | * | |
da5c8135 AJ |
17 | * A sample usage for ulists is the enumeration of directed graphs without |
18 | * visiting a node twice. The pseudo-code could look like this: | |
19 | * | |
20 | * ulist = ulist_alloc(); | |
21 | * ulist_add(ulist, root); | |
cd1b413c | 22 | * ULIST_ITER_INIT(&uiter); |
da5c8135 | 23 | * |
cd1b413c | 24 | * while ((elem = ulist_next(ulist, &uiter)) { |
da5c8135 AJ |
25 | * for (all child nodes n in elem) |
26 | * ulist_add(ulist, n); | |
27 | * do something useful with the node; | |
28 | * } | |
29 | * ulist_free(ulist); | |
30 | * | |
01327610 | 31 | * This assumes the graph nodes are addressable by u64. This stems from the |
da5c8135 AJ |
32 | * usage for tree enumeration in btrfs, where the logical addresses are |
33 | * 64 bit. | |
34 | * | |
35 | * It is also useful for tree enumeration which could be done elegantly | |
36 | * recursively, but is not possible due to kernel stack limitations. The | |
37 | * loop would be similar to the above. | |
38 | */ | |
39 | ||
43dd529a DS |
40 | /* |
41 | * Freshly initialize a ulist. | |
42 | * | |
da5c8135 AJ |
43 | * @ulist: the ulist to initialize |
44 | * | |
45 | * Note: don't use this function to init an already used ulist, use | |
46 | * ulist_reinit instead. | |
47 | */ | |
48 | void ulist_init(struct ulist *ulist) | |
49 | { | |
4c7a6f74 | 50 | INIT_LIST_HEAD(&ulist->nodes); |
f7f82b81 | 51 | ulist->root = RB_ROOT; |
4c7a6f74 | 52 | ulist->nnodes = 0; |
da5c8135 | 53 | } |
da5c8135 | 54 | |
43dd529a DS |
55 | /* |
56 | * Free up additionally allocated memory for the ulist. | |
57 | * | |
da5c8135 AJ |
58 | * @ulist: the ulist from which to free the additional memory |
59 | * | |
60 | * This is useful in cases where the base 'struct ulist' has been statically | |
61 | * allocated. | |
62 | */ | |
6655bc3d | 63 | void ulist_release(struct ulist *ulist) |
da5c8135 | 64 | { |
4c7a6f74 WS |
65 | struct ulist_node *node; |
66 | struct ulist_node *next; | |
67 | ||
68 | list_for_each_entry_safe(node, next, &ulist->nodes, list) { | |
69 | kfree(node); | |
70 | } | |
f7f82b81 | 71 | ulist->root = RB_ROOT; |
4c7a6f74 | 72 | INIT_LIST_HEAD(&ulist->nodes); |
da5c8135 | 73 | } |
da5c8135 | 74 | |
43dd529a DS |
75 | /* |
76 | * Prepare a ulist for reuse. | |
77 | * | |
da5c8135 AJ |
78 | * @ulist: ulist to be reused |
79 | * | |
80 | * Free up all additional memory allocated for the list elements and reinit | |
81 | * the ulist. | |
82 | */ | |
83 | void ulist_reinit(struct ulist *ulist) | |
84 | { | |
6655bc3d | 85 | ulist_release(ulist); |
da5c8135 AJ |
86 | ulist_init(ulist); |
87 | } | |
da5c8135 | 88 | |
43dd529a DS |
89 | /* |
90 | * Dynamically allocate a ulist. | |
91 | * | |
da5c8135 AJ |
92 | * @gfp_mask: allocation flags to for base allocation |
93 | * | |
94 | * The allocated ulist will be returned in an initialized state. | |
95 | */ | |
2eec6c81 | 96 | struct ulist *ulist_alloc(gfp_t gfp_mask) |
da5c8135 AJ |
97 | { |
98 | struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask); | |
99 | ||
100 | if (!ulist) | |
101 | return NULL; | |
102 | ||
103 | ulist_init(ulist); | |
104 | ||
105 | return ulist; | |
106 | } | |
da5c8135 | 107 | |
43dd529a DS |
108 | /* |
109 | * Free dynamically allocated ulist. | |
110 | * | |
da5c8135 AJ |
111 | * @ulist: ulist to free |
112 | * | |
6655bc3d | 113 | * It is not necessary to call ulist_release before. |
da5c8135 AJ |
114 | */ |
115 | void ulist_free(struct ulist *ulist) | |
116 | { | |
117 | if (!ulist) | |
118 | return; | |
6655bc3d | 119 | ulist_release(ulist); |
da5c8135 AJ |
120 | kfree(ulist); |
121 | } | |
da5c8135 | 122 | |
f7f82b81 WS |
123 | static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val) |
124 | { | |
125 | struct rb_node *n = ulist->root.rb_node; | |
126 | struct ulist_node *u = NULL; | |
127 | ||
128 | while (n) { | |
129 | u = rb_entry(n, struct ulist_node, rb_node); | |
130 | if (u->val < val) | |
131 | n = n->rb_right; | |
132 | else if (u->val > val) | |
133 | n = n->rb_left; | |
134 | else | |
135 | return u; | |
136 | } | |
137 | return NULL; | |
138 | } | |
139 | ||
d4b80404 QW |
140 | static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node) |
141 | { | |
142 | rb_erase(&node->rb_node, &ulist->root); | |
143 | list_del(&node->list); | |
144 | kfree(node); | |
145 | BUG_ON(ulist->nnodes == 0); | |
146 | ulist->nnodes--; | |
147 | } | |
148 | ||
f7f82b81 WS |
149 | static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins) |
150 | { | |
151 | struct rb_node **p = &ulist->root.rb_node; | |
152 | struct rb_node *parent = NULL; | |
153 | struct ulist_node *cur = NULL; | |
154 | ||
155 | while (*p) { | |
156 | parent = *p; | |
157 | cur = rb_entry(parent, struct ulist_node, rb_node); | |
158 | ||
159 | if (cur->val < ins->val) | |
160 | p = &(*p)->rb_right; | |
161 | else if (cur->val > ins->val) | |
162 | p = &(*p)->rb_left; | |
163 | else | |
164 | return -EEXIST; | |
165 | } | |
166 | rb_link_node(&ins->rb_node, parent, p); | |
167 | rb_insert_color(&ins->rb_node, &ulist->root); | |
168 | return 0; | |
169 | } | |
170 | ||
43dd529a DS |
171 | /* |
172 | * Add an element to the ulist. | |
173 | * | |
da5c8135 AJ |
174 | * @ulist: ulist to add the element to |
175 | * @val: value to add to ulist | |
176 | * @aux: auxiliary value to store along with val | |
177 | * @gfp_mask: flags to use for allocation | |
178 | * | |
179 | * Note: locking must be provided by the caller. In case of rwlocks write | |
180 | * locking is needed | |
181 | * | |
182 | * Add an element to a ulist. The @val will only be added if it doesn't | |
183 | * already exist. If it is added, the auxiliary value @aux is stored along with | |
184 | * it. In case @val already exists in the ulist, @aux is ignored, even if | |
185 | * it differs from the already stored value. | |
186 | * | |
187 | * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been | |
188 | * inserted. | |
189 | * In case of allocation failure -ENOMEM is returned and the ulist stays | |
190 | * unaltered. | |
191 | */ | |
34d73f54 | 192 | int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask) |
3301958b JS |
193 | { |
194 | return ulist_add_merge(ulist, val, aux, NULL, gfp_mask); | |
195 | } | |
196 | ||
34d73f54 AB |
197 | int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, |
198 | u64 *old_aux, gfp_t gfp_mask) | |
da5c8135 | 199 | { |
4c7a6f74 WS |
200 | int ret; |
201 | struct ulist_node *node; | |
202 | ||
f7f82b81 WS |
203 | node = ulist_rbtree_search(ulist, val); |
204 | if (node) { | |
205 | if (old_aux) | |
206 | *old_aux = node->aux; | |
207 | return 0; | |
da5c8135 | 208 | } |
4c7a6f74 WS |
209 | node = kmalloc(sizeof(*node), gfp_mask); |
210 | if (!node) | |
211 | return -ENOMEM; | |
da5c8135 | 212 | |
4c7a6f74 WS |
213 | node->val = val; |
214 | node->aux = aux; | |
da5c8135 | 215 | |
4c7a6f74 WS |
216 | ret = ulist_rbtree_insert(ulist, node); |
217 | ASSERT(!ret); | |
218 | list_add_tail(&node->list, &ulist->nodes); | |
219 | ulist->nnodes++; | |
da5c8135 AJ |
220 | |
221 | return 1; | |
222 | } | |
da5c8135 | 223 | |
d4b80404 | 224 | /* |
9580503b DS |
225 | * Delete one node from ulist. |
226 | * | |
d4b80404 QW |
227 | * @ulist: ulist to remove node from |
228 | * @val: value to delete | |
229 | * @aux: aux to delete | |
230 | * | |
231 | * The deletion will only be done when *BOTH* val and aux matches. | |
232 | * Return 0 for successful delete. | |
233 | * Return > 0 for not found. | |
234 | */ | |
235 | int ulist_del(struct ulist *ulist, u64 val, u64 aux) | |
236 | { | |
237 | struct ulist_node *node; | |
238 | ||
239 | node = ulist_rbtree_search(ulist, val); | |
240 | /* Not found */ | |
241 | if (!node) | |
242 | return 1; | |
243 | ||
244 | if (node->aux != aux) | |
245 | return 1; | |
246 | ||
247 | /* Found and delete */ | |
248 | ulist_rbtree_erase(ulist, node); | |
249 | return 0; | |
250 | } | |
251 | ||
43dd529a DS |
252 | /* |
253 | * Iterate ulist. | |
254 | * | |
da5c8135 | 255 | * @ulist: ulist to iterate |
cd1b413c | 256 | * @uiter: iterator variable, initialized with ULIST_ITER_INIT(&iterator) |
da5c8135 AJ |
257 | * |
258 | * Note: locking must be provided by the caller. In case of rwlocks only read | |
259 | * locking is needed | |
260 | * | |
cd1b413c JS |
261 | * This function is used to iterate an ulist. |
262 | * It returns the next element from the ulist or %NULL when the | |
da5c8135 AJ |
263 | * end is reached. No guarantee is made with respect to the order in which |
264 | * the elements are returned. They might neither be returned in order of | |
265 | * addition nor in ascending order. | |
266 | * It is allowed to call ulist_add during an enumeration. Newly added items | |
267 | * are guaranteed to show up in the running enumeration. | |
268 | */ | |
fa104a87 | 269 | struct ulist_node *ulist_next(const struct ulist *ulist, struct ulist_iterator *uiter) |
da5c8135 | 270 | { |
4c7a6f74 WS |
271 | struct ulist_node *node; |
272 | ||
273 | if (list_empty(&ulist->nodes)) | |
da5c8135 | 274 | return NULL; |
4c7a6f74 | 275 | if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes) |
da5c8135 | 276 | return NULL; |
4c7a6f74 WS |
277 | if (uiter->cur_list) { |
278 | uiter->cur_list = uiter->cur_list->next; | |
279 | } else { | |
280 | uiter->cur_list = ulist->nodes.next; | |
4c7a6f74 WS |
281 | } |
282 | node = list_entry(uiter->cur_list, struct ulist_node, list); | |
4c7a6f74 | 283 | return node; |
da5c8135 | 284 | } |