1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 2011 STRATO AG |
4 | * written by Arne Jansen <sensille@gmx.net> |
5 | */ |
6 | |
7 | #include <linux/slab.h> |
8 | #include "messages.h" |
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 | * |
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); |
22 | * ULIST_ITER_INIT(&uiter); |
23 | * |
24 | * while ((elem = ulist_next(ulist, &uiter)) { |
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 | * |
31 | * This assumes the graph nodes are addressable by u64. This stems from the |
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 | |
40 | /* |
41 | * Freshly initialize a ulist. |
42 | * |
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 | { |
50 | INIT_LIST_HEAD(list: &ulist->nodes); |
51 | ulist->root = RB_ROOT; |
52 | ulist->nnodes = 0; |
53 | } |
54 | |
55 | /* |
56 | * Free up additionally allocated memory for the ulist. |
57 | * |
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 | */ |
63 | void ulist_release(struct ulist *ulist) |
64 | { |
65 | struct ulist_node *node; |
66 | struct ulist_node *next; |
67 | |
68 | list_for_each_entry_safe(node, next, &ulist->nodes, list) { |
69 | kfree(objp: node); |
70 | } |
71 | ulist->root = RB_ROOT; |
72 | INIT_LIST_HEAD(list: &ulist->nodes); |
73 | } |
74 | |
75 | /* |
76 | * Prepare a ulist for reuse. |
77 | * |
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 | { |
85 | ulist_release(ulist); |
86 | ulist_init(ulist); |
87 | } |
88 | |
89 | /* |
90 | * Dynamically allocate a ulist. |
91 | * |
92 | * @gfp_mask: allocation flags to for base allocation |
93 | * |
94 | * The allocated ulist will be returned in an initialized state. |
95 | */ |
96 | struct ulist *ulist_alloc(gfp_t gfp_mask) |
97 | { |
98 | struct ulist *ulist = kmalloc(size: sizeof(*ulist), flags: gfp_mask); |
99 | |
100 | if (!ulist) |
101 | return NULL; |
102 | |
103 | ulist_init(ulist); |
104 | |
105 | return ulist; |
106 | } |
107 | |
108 | /* |
109 | * Free dynamically allocated ulist. |
110 | * |
111 | * @ulist: ulist to free |
112 | * |
113 | * It is not necessary to call ulist_release before. |
114 | */ |
115 | void ulist_free(struct ulist *ulist) |
116 | { |
117 | if (!ulist) |
118 | return; |
119 | ulist_release(ulist); |
120 | kfree(objp: ulist); |
121 | } |
122 | |
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 | |
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(entry: &node->list); |
144 | kfree(objp: node); |
145 | BUG_ON(ulist->nnodes == 0); |
146 | ulist->nnodes--; |
147 | } |
148 | |
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(node: &ins->rb_node, parent, rb_link: p); |
167 | rb_insert_color(&ins->rb_node, &ulist->root); |
168 | return 0; |
169 | } |
170 | |
171 | /* |
172 | * Add an element to the ulist. |
173 | * |
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 | */ |
192 | int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask) |
193 | { |
194 | return ulist_add_merge(ulist, val, aux, NULL, gfp_mask); |
195 | } |
196 | |
197 | int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, |
198 | u64 *old_aux, gfp_t gfp_mask) |
199 | { |
200 | int ret; |
201 | struct ulist_node *node; |
202 | |
203 | node = ulist_rbtree_search(ulist, val); |
204 | if (node) { |
205 | if (old_aux) |
206 | *old_aux = node->aux; |
207 | return 0; |
208 | } |
209 | node = kmalloc(size: sizeof(*node), flags: gfp_mask); |
210 | if (!node) |
211 | return -ENOMEM; |
212 | |
213 | node->val = val; |
214 | node->aux = aux; |
215 | |
216 | ret = ulist_rbtree_insert(ulist, ins: node); |
217 | ASSERT(!ret); |
218 | list_add_tail(new: &node->list, head: &ulist->nodes); |
219 | ulist->nnodes++; |
220 | |
221 | return 1; |
222 | } |
223 | |
224 | /* |
225 | * Delete one node from ulist. |
226 | * |
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 | |
252 | /* |
253 | * Iterate ulist. |
254 | * |
255 | * @ulist: ulist to iterate |
256 | * @uiter: iterator variable, initialized with ULIST_ITER_INIT(&iterator) |
257 | * |
258 | * Note: locking must be provided by the caller. In case of rwlocks only read |
259 | * locking is needed |
260 | * |
261 | * This function is used to iterate an ulist. |
262 | * It returns the next element from the ulist or %NULL when the |
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 | */ |
269 | struct ulist_node *ulist_next(const struct ulist *ulist, struct ulist_iterator *uiter) |
270 | { |
271 | struct ulist_node *node; |
272 | |
273 | if (list_empty(head: &ulist->nodes)) |
274 | return NULL; |
275 | if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes) |
276 | return NULL; |
277 | if (uiter->cur_list) { |
278 | uiter->cur_list = uiter->cur_list->next; |
279 | } else { |
280 | uiter->cur_list = ulist->nodes.next; |
281 | } |
282 | node = list_entry(uiter->cur_list, struct ulist_node, list); |
283 | return node; |
284 | } |
285 | |