1 /**************************************************************************
2 *
3 * Copyright 2006-2008 Tungsten Graphics, Inc., Cedar Park, TX., USA.
4 * All Rights Reserved.
5 * Copyright 2009 VMware, Inc., Palo Alto, CA., USA.
6 * All Rights Reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a
9 * copy of this software and associated documentation files (the
10 * "Software"), to deal in the Software without restriction, including
11 * without limitation the rights to use, copy, modify, merge, publish,
12 * distribute, sub license, and/or sell copies of the Software, and to
13 * permit persons to whom the Software is furnished to do so, subject to
14 * the following conditions:
15 *
16 * The above copyright notice and this permission notice (including the
17 * next paragraph) shall be included in all copies or substantial portions
18 * of the Software.
19 *
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
23 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
24 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
25 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
26 * USE OR OTHER DEALINGS IN THE SOFTWARE.
27 *
28 **************************************************************************/
29
30 /*
31 * Generic simple memory manager implementation. Intended to be used as a base
32 * class implementation for more advanced memory managers.
33 *
34 * Note that the algorithm used is quite simple and there might be substantial
35 * performance gains if a smarter free list is implemented. Currently it is just an
36 * unordered stack of free regions. This could easily be improved if an RB-tree
37 * is used instead. At least if we expect heavy fragmentation.
38 * Note that this implementation is more or less identical to the drm core manager
39 * in the linux kernel.
40 *
41 * Authors:
42 * Thomas Hellstr�m <thomas-at-tungstengraphics-dot-com>
43 */
44
45 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "wsbm_mm.h"
50 #include <errno.h>
51 #include <stdlib.h>
52
53 unsigned long
wsbmMMTailSpace(struct _WsbmMM * mm)54 wsbmMMTailSpace(struct _WsbmMM *mm)
55 {
56 struct _WsbmListHead *tail_node;
57 struct _WsbmMMNode *entry;
58
59 tail_node = mm->ml_entry.prev;
60 entry = WSBMLISTENTRY(tail_node, struct _WsbmMMNode, ml_entry);
61
62 if (!entry->free)
63 return 0;
64
65 return entry->size;
66 }
67
68 int
wsbmMMRemoveSpaceFromTail(struct _WsbmMM * mm,unsigned long size)69 wsbmMMRemoveSpaceFromTail(struct _WsbmMM *mm, unsigned long size)
70 {
71 struct _WsbmListHead *tail_node;
72 struct _WsbmMMNode *entry;
73
74 tail_node = mm->ml_entry.prev;
75 entry = WSBMLISTENTRY(tail_node, struct _WsbmMMNode, ml_entry);
76
77 if (!entry->free)
78 return -ENOMEM;
79
80 if (entry->size <= size)
81 return -ENOMEM;
82
83 entry->size -= size;
84 return 0;
85 }
86
87 static int
wsbmMMCreateTailNode(struct _WsbmMM * mm,unsigned long start,unsigned long size)88 wsbmMMCreateTailNode(struct _WsbmMM *mm,
89 unsigned long start, unsigned long size)
90 {
91 struct _WsbmMMNode *child;
92
93 child = (struct _WsbmMMNode *)malloc(sizeof(*child));
94 if (!child)
95 return -ENOMEM;
96
97 child->free = 1;
98 child->size = size;
99 child->start = start;
100 child->mm = mm;
101
102 WSBMLISTADDTAIL(&child->ml_entry, &mm->ml_entry);
103 WSBMLISTADDTAIL(&child->fl_entry, &mm->fl_entry);
104
105 return 0;
106 }
107
108 static struct _WsbmMMNode *
wsbmMMSplitAtStart(struct _WsbmMMNode * parent,unsigned long size)109 wsbmMMSplitAtStart(struct _WsbmMMNode *parent, unsigned long size)
110 {
111 struct _WsbmMMNode *child;
112
113 child = (struct _WsbmMMNode *)malloc(sizeof(*child));
114 if (!child)
115 return NULL;
116
117 WSBMINITLISTHEAD(&child->fl_entry);
118
119 child->free = 0;
120 child->size = size;
121 child->start = parent->start;
122 child->mm = parent->mm;
123
124 WSBMLISTADDTAIL(&child->ml_entry, &parent->ml_entry);
125 WSBMINITLISTHEAD(&child->fl_entry);
126
127 parent->size -= size;
128 parent->start += size;
129 return child;
130 }
131
132 struct _WsbmMMNode *
wsbmMMGetBlock(struct _WsbmMMNode * parent,unsigned long size,unsigned alignment)133 wsbmMMGetBlock(struct _WsbmMMNode *parent,
134 unsigned long size, unsigned alignment)
135 {
136
137 struct _WsbmMMNode *align_splitoff = NULL;
138 struct _WsbmMMNode *child;
139 unsigned tmp = 0;
140
141 if (alignment)
142 tmp = parent->start % alignment;
143
144 if (tmp) {
145 align_splitoff = wsbmMMSplitAtStart(parent, alignment - tmp);
146 if (!align_splitoff)
147 return NULL;
148 }
149
150 if (parent->size == size) {
151 WSBMLISTDELINIT(&parent->fl_entry);
152 parent->free = 0;
153 return parent;
154 } else {
155 child = wsbmMMSplitAtStart(parent, size);
156 }
157
158 if (align_splitoff)
159 wsbmMMPutBlock(align_splitoff);
160
161 return child;
162 }
163
164 /*
165 * Put a block. Merge with the previous and / or next block if they are free.
166 * Otherwise add to the free stack.
167 */
168
169 void
wsbmMMPutBlock(struct _WsbmMMNode * cur)170 wsbmMMPutBlock(struct _WsbmMMNode *cur)
171 {
172
173 struct _WsbmMM *mm = cur->mm;
174 struct _WsbmListHead *cur_head = &cur->ml_entry;
175 struct _WsbmListHead *root_head = &mm->ml_entry;
176 struct _WsbmMMNode *prev_node = NULL;
177 struct _WsbmMMNode *next_node;
178
179 int merged = 0;
180
181 if (cur_head->prev != root_head) {
182 prev_node =
183 WSBMLISTENTRY(cur_head->prev, struct _WsbmMMNode, ml_entry);
184 if (prev_node->free) {
185 prev_node->size += cur->size;
186 merged = 1;
187 }
188 }
189 if (cur_head->next != root_head) {
190 next_node =
191 WSBMLISTENTRY(cur_head->next, struct _WsbmMMNode, ml_entry);
192 if (next_node->free) {
193 if (merged) {
194 prev_node->size += next_node->size;
195 WSBMLISTDEL(&next_node->ml_entry);
196 WSBMLISTDEL(&next_node->fl_entry);
197 free(next_node);
198 } else {
199 next_node->size += cur->size;
200 next_node->start = cur->start;
201 merged = 1;
202 }
203 }
204 }
205 if (!merged) {
206 cur->free = 1;
207 WSBMLISTADD(&cur->fl_entry, &mm->fl_entry);
208 } else {
209 WSBMLISTDEL(&cur->ml_entry);
210 free(cur);
211 }
212 }
213
214 struct _WsbmMMNode *
wsbmMMSearchFree(const struct _WsbmMM * mm,unsigned long size,unsigned alignment,int best_match)215 wsbmMMSearchFree(const struct _WsbmMM *mm,
216 unsigned long size, unsigned alignment, int best_match)
217 {
218 struct _WsbmListHead *list;
219 const struct _WsbmListHead *free_stack = &mm->fl_entry;
220 struct _WsbmMMNode *entry;
221 struct _WsbmMMNode *best;
222 unsigned long best_size;
223 unsigned wasted;
224
225 best = NULL;
226 best_size = ~0UL;
227
228 WSBMLISTFOREACH(list, free_stack) {
229 entry = WSBMLISTENTRY(list, struct _WsbmMMNode, fl_entry);
230
231 wasted = 0;
232
233 if (entry->size < size)
234 continue;
235
236 if (alignment) {
237 register unsigned tmp = entry->start % alignment;
238
239 if (tmp)
240 wasted += alignment - tmp;
241 }
242
243 if (entry->size >= size + wasted) {
244 if (!best_match)
245 return entry;
246 if (size < best_size) {
247 best = entry;
248 best_size = entry->size;
249 }
250 }
251 }
252
253 return best;
254 }
255
256 int
wsbmMMclean(struct _WsbmMM * mm)257 wsbmMMclean(struct _WsbmMM *mm)
258 {
259 struct _WsbmListHead *head = &mm->ml_entry;
260
261 return (head->next->next == head);
262 }
263
264 int
wsbmMMinit(struct _WsbmMM * mm,unsigned long start,unsigned long size)265 wsbmMMinit(struct _WsbmMM *mm, unsigned long start, unsigned long size)
266 {
267 WSBMINITLISTHEAD(&mm->ml_entry);
268 WSBMINITLISTHEAD(&mm->fl_entry);
269
270 return wsbmMMCreateTailNode(mm, start, size);
271 }
272
273 void
wsbmMMtakedown(struct _WsbmMM * mm)274 wsbmMMtakedown(struct _WsbmMM *mm)
275 {
276 struct _WsbmListHead *bnode = mm->fl_entry.next;
277 struct _WsbmMMNode *entry;
278
279 entry = WSBMLISTENTRY(bnode, struct _WsbmMMNode, fl_entry);
280
281 if (entry->ml_entry.next != &mm->ml_entry ||
282 entry->fl_entry.next != &mm->fl_entry) {
283 return;
284 }
285
286 WSBMLISTDEL(&entry->fl_entry);
287 WSBMLISTDEL(&entry->ml_entry);
288 free(entry);
289 }
290