Root/
Source at commit 6c17a31f1fc515425221067cb3ece599c09dbc5d created 12 years 8 months ago. By Werner Almesberger, atusb, atben: moved from spi/ to ieee802154/; renamed atusb to spi_atusb | |
---|---|
1 | /* |
2 | * Flexible array managed in PAGE_SIZE parts |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify |
5 | * it under the terms of the GNU General Public License as published by |
6 | * the Free Software Foundation; either version 2 of the License, or |
7 | * (at your option) any later version. |
8 | * |
9 | * This program is distributed in the hope that it will be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | * GNU General Public License for more details. |
13 | * |
14 | * You should have received a copy of the GNU General Public License |
15 | * along with this program; if not, write to the Free Software |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
17 | * |
18 | * Copyright IBM Corporation, 2009 |
19 | * |
20 | * Author: Dave Hansen <dave@linux.vnet.ibm.com> |
21 | */ |
22 | |
23 | #include <linux/flex_array.h> |
24 | #include <linux/slab.h> |
25 | #include <linux/stddef.h> |
26 | #include <linux/module.h> |
27 | |
28 | struct flex_array_part { |
29 | char elements[FLEX_ARRAY_PART_SIZE]; |
30 | }; |
31 | |
32 | /* |
33 | * If a user requests an allocation which is small |
34 | * enough, we may simply use the space in the |
35 | * flex_array->parts[] array to store the user |
36 | * data. |
37 | */ |
38 | static inline int elements_fit_in_base(struct flex_array *fa) |
39 | { |
40 | int data_size = fa->element_size * fa->total_nr_elements; |
41 | if (data_size <= FLEX_ARRAY_BASE_BYTES_LEFT) |
42 | return 1; |
43 | return 0; |
44 | } |
45 | |
46 | /** |
47 | * flex_array_alloc - allocate a new flexible array |
48 | * @element_size: the size of individual elements in the array |
49 | * @total: total number of elements that this should hold |
50 | * @flags: page allocation flags to use for base array |
51 | * |
52 | * Note: all locking must be provided by the caller. |
53 | * |
54 | * @total is used to size internal structures. If the user ever |
55 | * accesses any array indexes >=@total, it will produce errors. |
56 | * |
57 | * The maximum number of elements is defined as: the number of |
58 | * elements that can be stored in a page times the number of |
59 | * page pointers that we can fit in the base structure or (using |
60 | * integer math): |
61 | * |
62 | * (PAGE_SIZE/element_size) * (PAGE_SIZE-8)/sizeof(void *) |
63 | * |
64 | * Here's a table showing example capacities. Note that the maximum |
65 | * index that the get/put() functions is just nr_objects-1. This |
66 | * basically means that you get 4MB of storage on 32-bit and 2MB on |
67 | * 64-bit. |
68 | * |
69 | * |
70 | * Element size | Objects | Objects | |
71 | * PAGE_SIZE=4k | 32-bit | 64-bit | |
72 | * ---------------------------------| |
73 | * 1 bytes | 4186112 | 2093056 | |
74 | * 2 bytes | 2093056 | 1046528 | |
75 | * 3 bytes | 1395030 | 697515 | |
76 | * 4 bytes | 1046528 | 523264 | |
77 | * 32 bytes | 130816 | 65408 | |
78 | * 33 bytes | 126728 | 63364 | |
79 | * 2048 bytes | 2044 | 1022 | |
80 | * 2049 bytes | 1022 | 511 | |
81 | * void * | 1046528 | 261632 | |
82 | * |
83 | * Since 64-bit pointers are twice the size, we lose half the |
84 | * capacity in the base structure. Also note that no effort is made |
85 | * to efficiently pack objects across page boundaries. |
86 | */ |
87 | struct flex_array *flex_array_alloc(int element_size, unsigned int total, |
88 | gfp_t flags) |
89 | { |
90 | struct flex_array *ret; |
91 | int max_size = FLEX_ARRAY_NR_BASE_PTRS * |
92 | FLEX_ARRAY_ELEMENTS_PER_PART(element_size); |
93 | |
94 | /* max_size will end up 0 if element_size > PAGE_SIZE */ |
95 | if (total > max_size) |
96 | return NULL; |
97 | ret = kzalloc(sizeof(struct flex_array), flags); |
98 | if (!ret) |
99 | return NULL; |
100 | ret->element_size = element_size; |
101 | ret->total_nr_elements = total; |
102 | if (elements_fit_in_base(ret) && !(flags & __GFP_ZERO)) |
103 | memset(&ret->parts[0], FLEX_ARRAY_FREE, |
104 | FLEX_ARRAY_BASE_BYTES_LEFT); |
105 | return ret; |
106 | } |
107 | EXPORT_SYMBOL(flex_array_alloc); |
108 | |
109 | static int fa_element_to_part_nr(struct flex_array *fa, |
110 | unsigned int element_nr) |
111 | { |
112 | return element_nr / FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size); |
113 | } |
114 | |
115 | /** |
116 | * flex_array_free_parts - just free the second-level pages |
117 | * @fa: the flex array from which to free parts |
118 | * |
119 | * This is to be used in cases where the base 'struct flex_array' |
120 | * has been statically allocated and should not be free. |
121 | */ |
122 | void flex_array_free_parts(struct flex_array *fa) |
123 | { |
124 | int part_nr; |
125 | |
126 | if (elements_fit_in_base(fa)) |
127 | return; |
128 | for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) |
129 | kfree(fa->parts[part_nr]); |
130 | } |
131 | EXPORT_SYMBOL(flex_array_free_parts); |
132 | |
133 | void flex_array_free(struct flex_array *fa) |
134 | { |
135 | flex_array_free_parts(fa); |
136 | kfree(fa); |
137 | } |
138 | EXPORT_SYMBOL(flex_array_free); |
139 | |
140 | static unsigned int index_inside_part(struct flex_array *fa, |
141 | unsigned int element_nr) |
142 | { |
143 | unsigned int part_offset; |
144 | |
145 | part_offset = element_nr % |
146 | FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size); |
147 | return part_offset * fa->element_size; |
148 | } |
149 | |
150 | static struct flex_array_part * |
151 | __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) |
152 | { |
153 | struct flex_array_part *part = fa->parts[part_nr]; |
154 | if (!part) { |
155 | part = kmalloc(sizeof(struct flex_array_part), flags); |
156 | if (!part) |
157 | return NULL; |
158 | if (!(flags & __GFP_ZERO)) |
159 | memset(part, FLEX_ARRAY_FREE, |
160 | sizeof(struct flex_array_part)); |
161 | fa->parts[part_nr] = part; |
162 | } |
163 | return part; |
164 | } |
165 | |
166 | /** |
167 | * flex_array_put - copy data into the array at @element_nr |
168 | * @fa: the flex array to copy data into |
169 | * @element_nr: index of the position in which to insert |
170 | * the new element. |
171 | * @src: address of data to copy into the array |
172 | * @flags: page allocation flags to use for array expansion |
173 | * |
174 | * |
175 | * Note that this *copies* the contents of @src into |
176 | * the array. If you are trying to store an array of |
177 | * pointers, make sure to pass in &ptr instead of ptr. |
178 | * You may instead wish to use the flex_array_put_ptr() |
179 | * helper function. |
180 | * |
181 | * Locking must be provided by the caller. |
182 | */ |
183 | int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, |
184 | gfp_t flags) |
185 | { |
186 | int part_nr = fa_element_to_part_nr(fa, element_nr); |
187 | struct flex_array_part *part; |
188 | void *dst; |
189 | |
190 | if (element_nr >= fa->total_nr_elements) |
191 | return -ENOSPC; |
192 | if (elements_fit_in_base(fa)) |
193 | part = (struct flex_array_part *)&fa->parts[0]; |
194 | else { |
195 | part = __fa_get_part(fa, part_nr, flags); |
196 | if (!part) |
197 | return -ENOMEM; |
198 | } |
199 | dst = &part->elements[index_inside_part(fa, element_nr)]; |
200 | memcpy(dst, src, fa->element_size); |
201 | return 0; |
202 | } |
203 | EXPORT_SYMBOL(flex_array_put); |
204 | |
205 | /** |
206 | * flex_array_clear - clear element in array at @element_nr |
207 | * @fa: the flex array of the element. |
208 | * @element_nr: index of the position to clear. |
209 | * |
210 | * Locking must be provided by the caller. |
211 | */ |
212 | int flex_array_clear(struct flex_array *fa, unsigned int element_nr) |
213 | { |
214 | int part_nr = fa_element_to_part_nr(fa, element_nr); |
215 | struct flex_array_part *part; |
216 | void *dst; |
217 | |
218 | if (element_nr >= fa->total_nr_elements) |
219 | return -ENOSPC; |
220 | if (elements_fit_in_base(fa)) |
221 | part = (struct flex_array_part *)&fa->parts[0]; |
222 | else { |
223 | part = fa->parts[part_nr]; |
224 | if (!part) |
225 | return -EINVAL; |
226 | } |
227 | dst = &part->elements[index_inside_part(fa, element_nr)]; |
228 | memset(dst, FLEX_ARRAY_FREE, fa->element_size); |
229 | return 0; |
230 | } |
231 | EXPORT_SYMBOL(flex_array_clear); |
232 | |
233 | /** |
234 | * flex_array_prealloc - guarantee that array space exists |
235 | * @fa: the flex array for which to preallocate parts |
236 | * @start: index of first array element for which space is allocated |
237 | * @end: index of last (inclusive) element for which space is allocated |
238 | * @flags: page allocation flags |
239 | * |
240 | * This will guarantee that no future calls to flex_array_put() |
241 | * will allocate memory. It can be used if you are expecting to |
242 | * be holding a lock or in some atomic context while writing |
243 | * data into the array. |
244 | * |
245 | * Locking must be provided by the caller. |
246 | */ |
247 | int flex_array_prealloc(struct flex_array *fa, unsigned int start, |
248 | unsigned int end, gfp_t flags) |
249 | { |
250 | int start_part; |
251 | int end_part; |
252 | int part_nr; |
253 | struct flex_array_part *part; |
254 | |
255 | if (start >= fa->total_nr_elements || end >= fa->total_nr_elements) |
256 | return -ENOSPC; |
257 | if (elements_fit_in_base(fa)) |
258 | return 0; |
259 | start_part = fa_element_to_part_nr(fa, start); |
260 | end_part = fa_element_to_part_nr(fa, end); |
261 | for (part_nr = start_part; part_nr <= end_part; part_nr++) { |
262 | part = __fa_get_part(fa, part_nr, flags); |
263 | if (!part) |
264 | return -ENOMEM; |
265 | } |
266 | return 0; |
267 | } |
268 | EXPORT_SYMBOL(flex_array_prealloc); |
269 | |
270 | /** |
271 | * flex_array_get - pull data back out of the array |
272 | * @fa: the flex array from which to extract data |
273 | * @element_nr: index of the element to fetch from the array |
274 | * |
275 | * Returns a pointer to the data at index @element_nr. Note |
276 | * that this is a copy of the data that was passed in. If you |
277 | * are using this to store pointers, you'll get back &ptr. You |
278 | * may instead wish to use the flex_array_get_ptr helper. |
279 | * |
280 | * Locking must be provided by the caller. |
281 | */ |
282 | void *flex_array_get(struct flex_array *fa, unsigned int element_nr) |
283 | { |
284 | int part_nr = fa_element_to_part_nr(fa, element_nr); |
285 | struct flex_array_part *part; |
286 | |
287 | if (element_nr >= fa->total_nr_elements) |
288 | return NULL; |
289 | if (elements_fit_in_base(fa)) |
290 | part = (struct flex_array_part *)&fa->parts[0]; |
291 | else { |
292 | part = fa->parts[part_nr]; |
293 | if (!part) |
294 | return NULL; |
295 | } |
296 | return &part->elements[index_inside_part(fa, element_nr)]; |
297 | } |
298 | EXPORT_SYMBOL(flex_array_get); |
299 | |
300 | /** |
301 | * flex_array_get_ptr - pull a ptr back out of the array |
302 | * @fa: the flex array from which to extract data |
303 | * @element_nr: index of the element to fetch from the array |
304 | * |
305 | * Returns the pointer placed in the flex array at element_nr using |
306 | * flex_array_put_ptr(). This function should not be called if the |
307 | * element in question was not set using the _put_ptr() helper. |
308 | */ |
309 | void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr) |
310 | { |
311 | void **tmp; |
312 | |
313 | tmp = flex_array_get(fa, element_nr); |
314 | if (!tmp) |
315 | return NULL; |
316 | |
317 | return *tmp; |
318 | } |
319 | EXPORT_SYMBOL(flex_array_get_ptr); |
320 | |
321 | static int part_is_free(struct flex_array_part *part) |
322 | { |
323 | int i; |
324 | |
325 | for (i = 0; i < sizeof(struct flex_array_part); i++) |
326 | if (part->elements[i] != FLEX_ARRAY_FREE) |
327 | return 0; |
328 | return 1; |
329 | } |
330 | |
331 | /** |
332 | * flex_array_shrink - free unused second-level pages |
333 | * @fa: the flex array to shrink |
334 | * |
335 | * Frees all second-level pages that consist solely of unused |
336 | * elements. Returns the number of pages freed. |
337 | * |
338 | * Locking must be provided by the caller. |
339 | */ |
340 | int flex_array_shrink(struct flex_array *fa) |
341 | { |
342 | struct flex_array_part *part; |
343 | int part_nr; |
344 | int ret = 0; |
345 | |
346 | if (elements_fit_in_base(fa)) |
347 | return ret; |
348 | for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) { |
349 | part = fa->parts[part_nr]; |
350 | if (!part) |
351 | continue; |
352 | if (part_is_free(part)) { |
353 | fa->parts[part_nr] = NULL; |
354 | kfree(part); |
355 | ret++; |
356 | } |
357 | } |
358 | return ret; |
359 | } |
360 | EXPORT_SYMBOL(flex_array_shrink); |
361 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9