Line data Source code
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 : #include "ctree.h"
11 :
12 : /*
13 : * ulist is a generic data structure to hold a collection of unique u64
14 : * values. The only operations it supports is adding to the list and
15 : * enumerating it.
16 : * It is possible to store an auxiliary value along with the key.
17 : *
18 : * A sample usage for ulists is the enumeration of directed graphs without
19 : * visiting a node twice. The pseudo-code could look like this:
20 : *
21 : * ulist = ulist_alloc();
22 : * ulist_add(ulist, root);
23 : * ULIST_ITER_INIT(&uiter);
24 : *
25 : * while ((elem = ulist_next(ulist, &uiter)) {
26 : * for (all child nodes n in elem)
27 : * ulist_add(ulist, n);
28 : * do something useful with the node;
29 : * }
30 : * ulist_free(ulist);
31 : *
32 : * This assumes the graph nodes are addressable by u64. This stems from the
33 : * usage for tree enumeration in btrfs, where the logical addresses are
34 : * 64 bit.
35 : *
36 : * It is also useful for tree enumeration which could be done elegantly
37 : * recursively, but is not possible due to kernel stack limitations. The
38 : * loop would be similar to the above.
39 : */
40 :
41 : /*
42 : * Freshly initialize a ulist.
43 : *
44 : * @ulist: the ulist to initialize
45 : *
46 : * Note: don't use this function to init an already used ulist, use
47 : * ulist_reinit instead.
48 : */
49 0 : void ulist_init(struct ulist *ulist)
50 : {
51 0 : INIT_LIST_HEAD(&ulist->nodes);
52 0 : ulist->root = RB_ROOT;
53 0 : ulist->nnodes = 0;
54 0 : }
55 :
56 : /*
57 : * Free up additionally allocated memory for the ulist.
58 : *
59 : * @ulist: the ulist from which to free the additional memory
60 : *
61 : * This is useful in cases where the base 'struct ulist' has been statically
62 : * allocated.
63 : */
64 0 : void ulist_release(struct ulist *ulist)
65 : {
66 0 : struct ulist_node *node;
67 0 : struct ulist_node *next;
68 :
69 0 : list_for_each_entry_safe(node, next, &ulist->nodes, list) {
70 0 : kfree(node);
71 : }
72 0 : ulist->root = RB_ROOT;
73 0 : INIT_LIST_HEAD(&ulist->nodes);
74 0 : }
75 :
76 : /*
77 : * Prepare a ulist for reuse.
78 : *
79 : * @ulist: ulist to be reused
80 : *
81 : * Free up all additional memory allocated for the list elements and reinit
82 : * the ulist.
83 : */
84 0 : void ulist_reinit(struct ulist *ulist)
85 : {
86 0 : ulist_release(ulist);
87 0 : ulist_init(ulist);
88 0 : }
89 :
90 : /*
91 : * Dynamically allocate a ulist.
92 : *
93 : * @gfp_mask: allocation flags to for base allocation
94 : *
95 : * The allocated ulist will be returned in an initialized state.
96 : */
97 0 : struct ulist *ulist_alloc(gfp_t gfp_mask)
98 : {
99 0 : struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask);
100 :
101 0 : if (!ulist)
102 : return NULL;
103 :
104 0 : ulist_init(ulist);
105 :
106 0 : return ulist;
107 : }
108 :
109 : /*
110 : * Free dynamically allocated ulist.
111 : *
112 : * @ulist: ulist to free
113 : *
114 : * It is not necessary to call ulist_release before.
115 : */
116 0 : void ulist_free(struct ulist *ulist)
117 : {
118 0 : if (!ulist)
119 : return;
120 0 : ulist_release(ulist);
121 0 : kfree(ulist);
122 : }
123 :
124 0 : static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val)
125 : {
126 0 : struct rb_node *n = ulist->root.rb_node;
127 0 : struct ulist_node *u = NULL;
128 :
129 0 : while (n) {
130 0 : u = rb_entry(n, struct ulist_node, rb_node);
131 0 : if (u->val < val)
132 0 : n = n->rb_right;
133 0 : else if (u->val > val)
134 0 : n = n->rb_left;
135 : else
136 0 : return u;
137 : }
138 : return NULL;
139 : }
140 :
141 0 : static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node)
142 : {
143 0 : rb_erase(&node->rb_node, &ulist->root);
144 0 : list_del(&node->list);
145 0 : kfree(node);
146 0 : BUG_ON(ulist->nnodes == 0);
147 0 : ulist->nnodes--;
148 0 : }
149 :
150 0 : static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins)
151 : {
152 0 : struct rb_node **p = &ulist->root.rb_node;
153 0 : struct rb_node *parent = NULL;
154 0 : struct ulist_node *cur = NULL;
155 :
156 0 : while (*p) {
157 0 : parent = *p;
158 0 : cur = rb_entry(parent, struct ulist_node, rb_node);
159 :
160 0 : if (cur->val < ins->val)
161 0 : p = &(*p)->rb_right;
162 0 : else if (cur->val > ins->val)
163 0 : p = &(*p)->rb_left;
164 : else
165 : return -EEXIST;
166 : }
167 0 : rb_link_node(&ins->rb_node, parent, p);
168 0 : rb_insert_color(&ins->rb_node, &ulist->root);
169 0 : return 0;
170 : }
171 :
172 : /*
173 : * Add an element to the ulist.
174 : *
175 : * @ulist: ulist to add the element to
176 : * @val: value to add to ulist
177 : * @aux: auxiliary value to store along with val
178 : * @gfp_mask: flags to use for allocation
179 : *
180 : * Note: locking must be provided by the caller. In case of rwlocks write
181 : * locking is needed
182 : *
183 : * Add an element to a ulist. The @val will only be added if it doesn't
184 : * already exist. If it is added, the auxiliary value @aux is stored along with
185 : * it. In case @val already exists in the ulist, @aux is ignored, even if
186 : * it differs from the already stored value.
187 : *
188 : * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been
189 : * inserted.
190 : * In case of allocation failure -ENOMEM is returned and the ulist stays
191 : * unaltered.
192 : */
193 0 : int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask)
194 : {
195 0 : return ulist_add_merge(ulist, val, aux, NULL, gfp_mask);
196 : }
197 :
198 0 : int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
199 : u64 *old_aux, gfp_t gfp_mask)
200 : {
201 0 : int ret;
202 0 : struct ulist_node *node;
203 :
204 0 : node = ulist_rbtree_search(ulist, val);
205 0 : if (node) {
206 0 : if (old_aux)
207 0 : *old_aux = node->aux;
208 0 : return 0;
209 : }
210 0 : node = kmalloc(sizeof(*node), gfp_mask);
211 0 : if (!node)
212 : return -ENOMEM;
213 :
214 0 : node->val = val;
215 0 : node->aux = aux;
216 :
217 0 : ret = ulist_rbtree_insert(ulist, node);
218 0 : ASSERT(!ret);
219 0 : list_add_tail(&node->list, &ulist->nodes);
220 0 : ulist->nnodes++;
221 :
222 0 : return 1;
223 : }
224 :
225 : /*
226 : * ulist_del - delete one node from ulist
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 0 : int ulist_del(struct ulist *ulist, u64 val, u64 aux)
236 : {
237 0 : struct ulist_node *node;
238 :
239 0 : node = ulist_rbtree_search(ulist, val);
240 : /* Not found */
241 0 : if (!node)
242 : return 1;
243 :
244 0 : if (node->aux != aux)
245 : return 1;
246 :
247 : /* Found and delete */
248 0 : ulist_rbtree_erase(ulist, node);
249 0 : 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 0 : struct ulist_node *ulist_next(const struct ulist *ulist, struct ulist_iterator *uiter)
270 : {
271 0 : struct ulist_node *node;
272 :
273 0 : if (list_empty(&ulist->nodes))
274 : return NULL;
275 0 : if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes)
276 : return NULL;
277 0 : if (uiter->cur_list) {
278 0 : uiter->cur_list = uiter->cur_list->next;
279 : } else {
280 0 : uiter->cur_list = ulist->nodes.next;
281 : }
282 0 : node = list_entry(uiter->cur_list, struct ulist_node, list);
283 0 : return node;
284 : }
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