Loading...
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 */
48void ulist_init(struct ulist *ulist)
49{
50 INIT_LIST_HEAD(&ulist->nodes);
51 ulist->root = RB_ROOT;
52 ulist->nnodes = 0;
53 ulist->prealloc = NULL;
54}
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 */
64void ulist_release(struct ulist *ulist)
65{
66 struct ulist_node *node;
67 struct ulist_node *next;
68
69 list_for_each_entry_safe(node, next, &ulist->nodes, list) {
70 kfree(node);
71 }
72 kfree(ulist->prealloc);
73 ulist->prealloc = NULL;
74 ulist->root = RB_ROOT;
75 INIT_LIST_HEAD(&ulist->nodes);
76}
77
78/*
79 * Prepare a ulist for reuse.
80 *
81 * @ulist: ulist to be reused
82 *
83 * Free up all additional memory allocated for the list elements and reinit
84 * the ulist.
85 */
86void ulist_reinit(struct ulist *ulist)
87{
88 ulist_release(ulist);
89 ulist_init(ulist);
90}
91
92/*
93 * Dynamically allocate a ulist.
94 *
95 * @gfp_mask: allocation flags to for base allocation
96 *
97 * The allocated ulist will be returned in an initialized state.
98 */
99struct ulist *ulist_alloc(gfp_t gfp_mask)
100{
101 struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask);
102
103 if (!ulist)
104 return NULL;
105
106 ulist_init(ulist);
107
108 return ulist;
109}
110
111void ulist_prealloc(struct ulist *ulist, gfp_t gfp_mask)
112{
113 if (!ulist->prealloc)
114 ulist->prealloc = kzalloc(sizeof(*ulist->prealloc), gfp_mask);
115}
116
117/*
118 * Free dynamically allocated ulist.
119 *
120 * @ulist: ulist to free
121 *
122 * It is not necessary to call ulist_release before.
123 */
124void ulist_free(struct ulist *ulist)
125{
126 if (!ulist)
127 return;
128 ulist_release(ulist);
129 kfree(ulist);
130}
131
132static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val)
133{
134 struct rb_node *n = ulist->root.rb_node;
135 struct ulist_node *u = NULL;
136
137 while (n) {
138 u = rb_entry(n, struct ulist_node, rb_node);
139 if (u->val < val)
140 n = n->rb_right;
141 else if (u->val > val)
142 n = n->rb_left;
143 else
144 return u;
145 }
146 return NULL;
147}
148
149static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node)
150{
151 rb_erase(&node->rb_node, &ulist->root);
152 list_del(&node->list);
153 kfree(node);
154 BUG_ON(ulist->nnodes == 0);
155 ulist->nnodes--;
156}
157
158static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins)
159{
160 struct rb_node **p = &ulist->root.rb_node;
161 struct rb_node *parent = NULL;
162 struct ulist_node *cur = NULL;
163
164 while (*p) {
165 parent = *p;
166 cur = rb_entry(parent, struct ulist_node, rb_node);
167
168 if (cur->val < ins->val)
169 p = &(*p)->rb_right;
170 else if (cur->val > ins->val)
171 p = &(*p)->rb_left;
172 else
173 return -EEXIST;
174 }
175 rb_link_node(&ins->rb_node, parent, p);
176 rb_insert_color(&ins->rb_node, &ulist->root);
177 return 0;
178}
179
180/*
181 * Add an element to the ulist.
182 *
183 * @ulist: ulist to add the element to
184 * @val: value to add to ulist
185 * @aux: auxiliary value to store along with val
186 * @gfp_mask: flags to use for allocation
187 *
188 * Note: locking must be provided by the caller. In case of rwlocks write
189 * locking is needed
190 *
191 * Add an element to a ulist. The @val will only be added if it doesn't
192 * already exist. If it is added, the auxiliary value @aux is stored along with
193 * it. In case @val already exists in the ulist, @aux is ignored, even if
194 * it differs from the already stored value.
195 *
196 * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been
197 * inserted.
198 * In case of allocation failure -ENOMEM is returned and the ulist stays
199 * unaltered.
200 */
201int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask)
202{
203 return ulist_add_merge(ulist, val, aux, NULL, gfp_mask);
204}
205
206int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
207 u64 *old_aux, gfp_t gfp_mask)
208{
209 int ret;
210 struct ulist_node *node;
211
212 node = ulist_rbtree_search(ulist, val);
213 if (node) {
214 if (old_aux)
215 *old_aux = node->aux;
216 return 0;
217 }
218
219 if (ulist->prealloc) {
220 node = ulist->prealloc;
221 ulist->prealloc = NULL;
222 } else {
223 node = kmalloc(sizeof(*node), gfp_mask);
224 if (!node)
225 return -ENOMEM;
226 }
227
228 node->val = val;
229 node->aux = aux;
230
231 ret = ulist_rbtree_insert(ulist, node);
232 ASSERT(!ret);
233 list_add_tail(&node->list, &ulist->nodes);
234 ulist->nnodes++;
235
236 return 1;
237}
238
239/*
240 * Delete one node from ulist.
241 *
242 * @ulist: ulist to remove node from
243 * @val: value to delete
244 * @aux: aux to delete
245 *
246 * The deletion will only be done when *BOTH* val and aux matches.
247 * Return 0 for successful delete.
248 * Return > 0 for not found.
249 */
250int ulist_del(struct ulist *ulist, u64 val, u64 aux)
251{
252 struct ulist_node *node;
253
254 node = ulist_rbtree_search(ulist, val);
255 /* Not found */
256 if (!node)
257 return 1;
258
259 if (node->aux != aux)
260 return 1;
261
262 /* Found and delete */
263 ulist_rbtree_erase(ulist, node);
264 return 0;
265}
266
267/*
268 * Iterate ulist.
269 *
270 * @ulist: ulist to iterate
271 * @uiter: iterator variable, initialized with ULIST_ITER_INIT(&iterator)
272 *
273 * Note: locking must be provided by the caller. In case of rwlocks only read
274 * locking is needed
275 *
276 * This function is used to iterate an ulist.
277 * It returns the next element from the ulist or %NULL when the
278 * end is reached. No guarantee is made with respect to the order in which
279 * the elements are returned. They might neither be returned in order of
280 * addition nor in ascending order.
281 * It is allowed to call ulist_add during an enumeration. Newly added items
282 * are guaranteed to show up in the running enumeration.
283 */
284struct ulist_node *ulist_next(const struct ulist *ulist, struct ulist_iterator *uiter)
285{
286 struct ulist_node *node;
287
288 if (list_empty(&ulist->nodes))
289 return NULL;
290 if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes)
291 return NULL;
292 if (uiter->cur_list) {
293 uiter->cur_list = uiter->cur_list->next;
294 } else {
295 uiter->cur_list = ulist->nodes.next;
296 }
297 node = list_entry(uiter->cur_list, struct ulist_node, list);
298 return node;
299}
1/*
2 * Copyright (C) 2011 STRATO AG
3 * written by Arne Jansen <sensille@gmx.net>
4 * Distributed under the GNU GPL license version 2.
5 */
6
7#include <linux/slab.h>
8#include <linux/module.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 * The implementation is preliminary and can probably be sped up
18 * significantly. A first step would be to store the values in an rbtree
19 * as soon as ULIST_SIZE is exceeded.
20 *
21 * A sample usage for ulists is the enumeration of directed graphs without
22 * visiting a node twice. The pseudo-code could look like this:
23 *
24 * ulist = ulist_alloc();
25 * ulist_add(ulist, root);
26 * ULIST_ITER_INIT(&uiter);
27 *
28 * while ((elem = ulist_next(ulist, &uiter)) {
29 * for (all child nodes n in elem)
30 * ulist_add(ulist, n);
31 * do something useful with the node;
32 * }
33 * ulist_free(ulist);
34 *
35 * This assumes the graph nodes are adressable by u64. This stems from the
36 * usage for tree enumeration in btrfs, where the logical addresses are
37 * 64 bit.
38 *
39 * It is also useful for tree enumeration which could be done elegantly
40 * recursively, but is not possible due to kernel stack limitations. The
41 * loop would be similar to the above.
42 */
43
44/**
45 * ulist_init - freshly initialize a ulist
46 * @ulist: the ulist to initialize
47 *
48 * Note: don't use this function to init an already used ulist, use
49 * ulist_reinit instead.
50 */
51void ulist_init(struct ulist *ulist)
52{
53 ulist->nnodes = 0;
54 ulist->nodes = ulist->int_nodes;
55 ulist->nodes_alloced = ULIST_SIZE;
56}
57EXPORT_SYMBOL(ulist_init);
58
59/**
60 * ulist_fini - free up additionally allocated memory for the ulist
61 * @ulist: the ulist from which to free the additional memory
62 *
63 * This is useful in cases where the base 'struct ulist' has been statically
64 * allocated.
65 */
66void ulist_fini(struct ulist *ulist)
67{
68 /*
69 * The first ULIST_SIZE elements are stored inline in struct ulist.
70 * Only if more elements are alocated they need to be freed.
71 */
72 if (ulist->nodes_alloced > ULIST_SIZE)
73 kfree(ulist->nodes);
74 ulist->nodes_alloced = 0; /* in case ulist_fini is called twice */
75}
76EXPORT_SYMBOL(ulist_fini);
77
78/**
79 * ulist_reinit - prepare a ulist for reuse
80 * @ulist: ulist to be reused
81 *
82 * Free up all additional memory allocated for the list elements and reinit
83 * the ulist.
84 */
85void ulist_reinit(struct ulist *ulist)
86{
87 ulist_fini(ulist);
88 ulist_init(ulist);
89}
90EXPORT_SYMBOL(ulist_reinit);
91
92/**
93 * ulist_alloc - dynamically allocate a ulist
94 * @gfp_mask: allocation flags to for base allocation
95 *
96 * The allocated ulist will be returned in an initialized state.
97 */
98struct ulist *ulist_alloc(gfp_t gfp_mask)
99{
100 struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask);
101
102 if (!ulist)
103 return NULL;
104
105 ulist_init(ulist);
106
107 return ulist;
108}
109EXPORT_SYMBOL(ulist_alloc);
110
111/**
112 * ulist_free - free dynamically allocated ulist
113 * @ulist: ulist to free
114 *
115 * It is not necessary to call ulist_fini before.
116 */
117void ulist_free(struct ulist *ulist)
118{
119 if (!ulist)
120 return;
121 ulist_fini(ulist);
122 kfree(ulist);
123}
124EXPORT_SYMBOL(ulist_free);
125
126/**
127 * ulist_add - add an element to the ulist
128 * @ulist: ulist to add the element to
129 * @val: value to add to ulist
130 * @aux: auxiliary value to store along with val
131 * @gfp_mask: flags to use for allocation
132 *
133 * Note: locking must be provided by the caller. In case of rwlocks write
134 * locking is needed
135 *
136 * Add an element to a ulist. The @val will only be added if it doesn't
137 * already exist. If it is added, the auxiliary value @aux is stored along with
138 * it. In case @val already exists in the ulist, @aux is ignored, even if
139 * it differs from the already stored value.
140 *
141 * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been
142 * inserted.
143 * In case of allocation failure -ENOMEM is returned and the ulist stays
144 * unaltered.
145 */
146int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
147 gfp_t gfp_mask)
148{
149 return ulist_add_merge(ulist, val, aux, NULL, gfp_mask);
150}
151
152int ulist_add_merge(struct ulist *ulist, u64 val, unsigned long aux,
153 unsigned long *old_aux, gfp_t gfp_mask)
154{
155 int i;
156
157 for (i = 0; i < ulist->nnodes; ++i) {
158 if (ulist->nodes[i].val == val) {
159 if (old_aux)
160 *old_aux = ulist->nodes[i].aux;
161 return 0;
162 }
163 }
164
165 if (ulist->nnodes >= ulist->nodes_alloced) {
166 u64 new_alloced = ulist->nodes_alloced + 128;
167 struct ulist_node *new_nodes;
168 void *old = NULL;
169
170 /*
171 * if nodes_alloced == ULIST_SIZE no memory has been allocated
172 * yet, so pass NULL to krealloc
173 */
174 if (ulist->nodes_alloced > ULIST_SIZE)
175 old = ulist->nodes;
176
177 new_nodes = krealloc(old, sizeof(*new_nodes) * new_alloced,
178 gfp_mask);
179 if (!new_nodes)
180 return -ENOMEM;
181
182 if (!old)
183 memcpy(new_nodes, ulist->int_nodes,
184 sizeof(ulist->int_nodes));
185
186 ulist->nodes = new_nodes;
187 ulist->nodes_alloced = new_alloced;
188 }
189 ulist->nodes[ulist->nnodes].val = val;
190 ulist->nodes[ulist->nnodes].aux = aux;
191 ++ulist->nnodes;
192
193 return 1;
194}
195EXPORT_SYMBOL(ulist_add);
196
197/**
198 * ulist_next - iterate ulist
199 * @ulist: ulist to iterate
200 * @uiter: iterator variable, initialized with ULIST_ITER_INIT(&iterator)
201 *
202 * Note: locking must be provided by the caller. In case of rwlocks only read
203 * locking is needed
204 *
205 * This function is used to iterate an ulist.
206 * It returns the next element from the ulist or %NULL when the
207 * end is reached. No guarantee is made with respect to the order in which
208 * the elements are returned. They might neither be returned in order of
209 * addition nor in ascending order.
210 * It is allowed to call ulist_add during an enumeration. Newly added items
211 * are guaranteed to show up in the running enumeration.
212 */
213struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter)
214{
215 if (ulist->nnodes == 0)
216 return NULL;
217 if (uiter->i < 0 || uiter->i >= ulist->nnodes)
218 return NULL;
219
220 return &ulist->nodes[uiter->i++];
221}
222EXPORT_SYMBOL(ulist_next);