Commit | Line | Data |
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0db9299f JA |
1 | /* |
2 | * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> | |
3 | * | |
4 | * Scatterlist handling helpers. | |
5 | * | |
6 | * This source code is licensed under the GNU General Public License, | |
7 | * Version 2. See the file COPYING for more details. | |
8 | */ | |
8bc3bcc9 | 9 | #include <linux/export.h> |
5a0e3ad6 | 10 | #include <linux/slab.h> |
0db9299f | 11 | #include <linux/scatterlist.h> |
b1adaf65 | 12 | #include <linux/highmem.h> |
b94de9bb | 13 | #include <linux/kmemleak.h> |
0db9299f JA |
14 | |
15 | /** | |
16 | * sg_next - return the next scatterlist entry in a list | |
17 | * @sg: The current sg entry | |
18 | * | |
19 | * Description: | |
20 | * Usually the next entry will be @sg@ + 1, but if this sg element is part | |
21 | * of a chained scatterlist, it could jump to the start of a new | |
22 | * scatterlist array. | |
23 | * | |
24 | **/ | |
25 | struct scatterlist *sg_next(struct scatterlist *sg) | |
26 | { | |
27 | #ifdef CONFIG_DEBUG_SG | |
28 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
29 | #endif | |
30 | if (sg_is_last(sg)) | |
31 | return NULL; | |
32 | ||
33 | sg++; | |
34 | if (unlikely(sg_is_chain(sg))) | |
35 | sg = sg_chain_ptr(sg); | |
36 | ||
37 | return sg; | |
38 | } | |
39 | EXPORT_SYMBOL(sg_next); | |
40 | ||
2e484610 ML |
41 | /** |
42 | * sg_nents - return total count of entries in scatterlist | |
43 | * @sg: The scatterlist | |
44 | * | |
45 | * Description: | |
46 | * Allows to know how many entries are in sg, taking into acount | |
47 | * chaining as well | |
48 | * | |
49 | **/ | |
50 | int sg_nents(struct scatterlist *sg) | |
51 | { | |
232f1b51 ML |
52 | int nents; |
53 | for (nents = 0; sg; sg = sg_next(sg)) | |
2e484610 | 54 | nents++; |
2e484610 ML |
55 | return nents; |
56 | } | |
57 | EXPORT_SYMBOL(sg_nents); | |
58 | ||
cfaed10d TL |
59 | /** |
60 | * sg_nents_for_len - return total count of entries in scatterlist | |
61 | * needed to satisfy the supplied length | |
62 | * @sg: The scatterlist | |
63 | * @len: The total required length | |
64 | * | |
65 | * Description: | |
66 | * Determines the number of entries in sg that are required to meet | |
67 | * the supplied length, taking into acount chaining as well | |
68 | * | |
69 | * Returns: | |
70 | * the number of sg entries needed, negative error on failure | |
71 | * | |
72 | **/ | |
73 | int sg_nents_for_len(struct scatterlist *sg, u64 len) | |
74 | { | |
75 | int nents; | |
76 | u64 total; | |
77 | ||
78 | if (!len) | |
79 | return 0; | |
80 | ||
81 | for (nents = 0, total = 0; sg; sg = sg_next(sg)) { | |
82 | nents++; | |
83 | total += sg->length; | |
84 | if (total >= len) | |
85 | return nents; | |
86 | } | |
87 | ||
88 | return -EINVAL; | |
89 | } | |
90 | EXPORT_SYMBOL(sg_nents_for_len); | |
2e484610 | 91 | |
0db9299f JA |
92 | /** |
93 | * sg_last - return the last scatterlist entry in a list | |
94 | * @sgl: First entry in the scatterlist | |
95 | * @nents: Number of entries in the scatterlist | |
96 | * | |
97 | * Description: | |
98 | * Should only be used casually, it (currently) scans the entire list | |
99 | * to get the last entry. | |
100 | * | |
101 | * Note that the @sgl@ pointer passed in need not be the first one, | |
102 | * the important bit is that @nents@ denotes the number of entries that | |
103 | * exist from @sgl@. | |
104 | * | |
105 | **/ | |
106 | struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) | |
107 | { | |
0db9299f JA |
108 | struct scatterlist *sg, *ret = NULL; |
109 | unsigned int i; | |
110 | ||
111 | for_each_sg(sgl, sg, nents, i) | |
112 | ret = sg; | |
113 | ||
0db9299f JA |
114 | #ifdef CONFIG_DEBUG_SG |
115 | BUG_ON(sgl[0].sg_magic != SG_MAGIC); | |
116 | BUG_ON(!sg_is_last(ret)); | |
117 | #endif | |
118 | return ret; | |
119 | } | |
120 | EXPORT_SYMBOL(sg_last); | |
121 | ||
122 | /** | |
123 | * sg_init_table - Initialize SG table | |
124 | * @sgl: The SG table | |
125 | * @nents: Number of entries in table | |
126 | * | |
127 | * Notes: | |
128 | * If this is part of a chained sg table, sg_mark_end() should be | |
129 | * used only on the last table part. | |
130 | * | |
131 | **/ | |
132 | void sg_init_table(struct scatterlist *sgl, unsigned int nents) | |
133 | { | |
134 | memset(sgl, 0, sizeof(*sgl) * nents); | |
f3851786 | 135 | sg_init_marker(sgl, nents); |
0db9299f JA |
136 | } |
137 | EXPORT_SYMBOL(sg_init_table); | |
138 | ||
139 | /** | |
140 | * sg_init_one - Initialize a single entry sg list | |
141 | * @sg: SG entry | |
142 | * @buf: Virtual address for IO | |
143 | * @buflen: IO length | |
144 | * | |
145 | **/ | |
146 | void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) | |
147 | { | |
148 | sg_init_table(sg, 1); | |
149 | sg_set_buf(sg, buf, buflen); | |
150 | } | |
151 | EXPORT_SYMBOL(sg_init_one); | |
152 | ||
153 | /* | |
154 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree | |
155 | * helpers. | |
156 | */ | |
157 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) | |
158 | { | |
b94de9bb CW |
159 | if (nents == SG_MAX_SINGLE_ALLOC) { |
160 | /* | |
161 | * Kmemleak doesn't track page allocations as they are not | |
162 | * commonly used (in a raw form) for kernel data structures. | |
163 | * As we chain together a list of pages and then a normal | |
164 | * kmalloc (tracked by kmemleak), in order to for that last | |
165 | * allocation not to become decoupled (and thus a | |
166 | * false-positive) we need to inform kmemleak of all the | |
167 | * intermediate allocations. | |
168 | */ | |
169 | void *ptr = (void *) __get_free_page(gfp_mask); | |
170 | kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); | |
171 | return ptr; | |
172 | } else | |
0db9299f JA |
173 | return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); |
174 | } | |
175 | ||
176 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) | |
177 | { | |
b94de9bb CW |
178 | if (nents == SG_MAX_SINGLE_ALLOC) { |
179 | kmemleak_free(sg); | |
0db9299f | 180 | free_page((unsigned long) sg); |
b94de9bb | 181 | } else |
0db9299f JA |
182 | kfree(sg); |
183 | } | |
184 | ||
185 | /** | |
186 | * __sg_free_table - Free a previously mapped sg table | |
187 | * @table: The sg table header to use | |
7cedb1f1 | 188 | * @max_ents: The maximum number of entries per single scatterlist |
c53c6d6a | 189 | * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk |
0db9299f JA |
190 | * @free_fn: Free function |
191 | * | |
192 | * Description: | |
7cedb1f1 JB |
193 | * Free an sg table previously allocated and setup with |
194 | * __sg_alloc_table(). The @max_ents value must be identical to | |
195 | * that previously used with __sg_alloc_table(). | |
0db9299f JA |
196 | * |
197 | **/ | |
7cedb1f1 | 198 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
c53c6d6a | 199 | bool skip_first_chunk, sg_free_fn *free_fn) |
0db9299f JA |
200 | { |
201 | struct scatterlist *sgl, *next; | |
202 | ||
203 | if (unlikely(!table->sgl)) | |
204 | return; | |
205 | ||
206 | sgl = table->sgl; | |
207 | while (table->orig_nents) { | |
208 | unsigned int alloc_size = table->orig_nents; | |
209 | unsigned int sg_size; | |
210 | ||
211 | /* | |
7cedb1f1 | 212 | * If we have more than max_ents segments left, |
0db9299f JA |
213 | * then assign 'next' to the sg table after the current one. |
214 | * sg_size is then one less than alloc size, since the last | |
215 | * element is the chain pointer. | |
216 | */ | |
7cedb1f1 JB |
217 | if (alloc_size > max_ents) { |
218 | next = sg_chain_ptr(&sgl[max_ents - 1]); | |
219 | alloc_size = max_ents; | |
0db9299f JA |
220 | sg_size = alloc_size - 1; |
221 | } else { | |
222 | sg_size = alloc_size; | |
223 | next = NULL; | |
224 | } | |
225 | ||
226 | table->orig_nents -= sg_size; | |
c21e59d8 | 227 | if (skip_first_chunk) |
c53c6d6a | 228 | skip_first_chunk = false; |
c21e59d8 TB |
229 | else |
230 | free_fn(sgl, alloc_size); | |
0db9299f JA |
231 | sgl = next; |
232 | } | |
233 | ||
234 | table->sgl = NULL; | |
235 | } | |
236 | EXPORT_SYMBOL(__sg_free_table); | |
237 | ||
238 | /** | |
239 | * sg_free_table - Free a previously allocated sg table | |
240 | * @table: The mapped sg table header | |
241 | * | |
242 | **/ | |
243 | void sg_free_table(struct sg_table *table) | |
244 | { | |
c53c6d6a | 245 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
0db9299f JA |
246 | } |
247 | EXPORT_SYMBOL(sg_free_table); | |
248 | ||
249 | /** | |
250 | * __sg_alloc_table - Allocate and initialize an sg table with given allocator | |
251 | * @table: The sg table header to use | |
252 | * @nents: Number of entries in sg list | |
7cedb1f1 | 253 | * @max_ents: The maximum number of entries the allocator returns per call |
0db9299f JA |
254 | * @gfp_mask: GFP allocation mask |
255 | * @alloc_fn: Allocator to use | |
256 | * | |
7cedb1f1 JB |
257 | * Description: |
258 | * This function returns a @table @nents long. The allocator is | |
259 | * defined to return scatterlist chunks of maximum size @max_ents. | |
260 | * Thus if @nents is bigger than @max_ents, the scatterlists will be | |
261 | * chained in units of @max_ents. | |
262 | * | |
0db9299f JA |
263 | * Notes: |
264 | * If this function returns non-0 (eg failure), the caller must call | |
265 | * __sg_free_table() to cleanup any leftover allocations. | |
266 | * | |
267 | **/ | |
7cedb1f1 | 268 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
c53c6d6a CH |
269 | unsigned int max_ents, struct scatterlist *first_chunk, |
270 | gfp_t gfp_mask, sg_alloc_fn *alloc_fn) | |
0db9299f JA |
271 | { |
272 | struct scatterlist *sg, *prv; | |
273 | unsigned int left; | |
274 | ||
27daabd9 DC |
275 | memset(table, 0, sizeof(*table)); |
276 | ||
277 | if (nents == 0) | |
278 | return -EINVAL; | |
308c09f1 | 279 | #ifndef CONFIG_ARCH_HAS_SG_CHAIN |
6fd59a83 NB |
280 | if (WARN_ON_ONCE(nents > max_ents)) |
281 | return -EINVAL; | |
0db9299f JA |
282 | #endif |
283 | ||
0db9299f JA |
284 | left = nents; |
285 | prv = NULL; | |
286 | do { | |
287 | unsigned int sg_size, alloc_size = left; | |
288 | ||
7cedb1f1 JB |
289 | if (alloc_size > max_ents) { |
290 | alloc_size = max_ents; | |
0db9299f JA |
291 | sg_size = alloc_size - 1; |
292 | } else | |
293 | sg_size = alloc_size; | |
294 | ||
295 | left -= sg_size; | |
296 | ||
c53c6d6a CH |
297 | if (first_chunk) { |
298 | sg = first_chunk; | |
299 | first_chunk = NULL; | |
300 | } else { | |
301 | sg = alloc_fn(alloc_size, gfp_mask); | |
302 | } | |
edce6820 JC |
303 | if (unlikely(!sg)) { |
304 | /* | |
305 | * Adjust entry count to reflect that the last | |
306 | * entry of the previous table won't be used for | |
307 | * linkage. Without this, sg_kfree() may get | |
308 | * confused. | |
309 | */ | |
310 | if (prv) | |
311 | table->nents = ++table->orig_nents; | |
312 | ||
313 | return -ENOMEM; | |
314 | } | |
0db9299f JA |
315 | |
316 | sg_init_table(sg, alloc_size); | |
317 | table->nents = table->orig_nents += sg_size; | |
318 | ||
319 | /* | |
320 | * If this is the first mapping, assign the sg table header. | |
321 | * If this is not the first mapping, chain previous part. | |
322 | */ | |
323 | if (prv) | |
7cedb1f1 | 324 | sg_chain(prv, max_ents, sg); |
0db9299f JA |
325 | else |
326 | table->sgl = sg; | |
327 | ||
328 | /* | |
329 | * If no more entries after this one, mark the end | |
330 | */ | |
331 | if (!left) | |
332 | sg_mark_end(&sg[sg_size - 1]); | |
333 | ||
0db9299f JA |
334 | prv = sg; |
335 | } while (left); | |
336 | ||
337 | return 0; | |
338 | } | |
339 | EXPORT_SYMBOL(__sg_alloc_table); | |
340 | ||
341 | /** | |
342 | * sg_alloc_table - Allocate and initialize an sg table | |
343 | * @table: The sg table header to use | |
344 | * @nents: Number of entries in sg list | |
345 | * @gfp_mask: GFP allocation mask | |
346 | * | |
347 | * Description: | |
348 | * Allocate and initialize an sg table. If @nents@ is larger than | |
349 | * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. | |
350 | * | |
351 | **/ | |
352 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) | |
353 | { | |
354 | int ret; | |
355 | ||
7cedb1f1 | 356 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
c53c6d6a | 357 | NULL, gfp_mask, sg_kmalloc); |
0db9299f | 358 | if (unlikely(ret)) |
c53c6d6a | 359 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
0db9299f JA |
360 | |
361 | return ret; | |
362 | } | |
363 | EXPORT_SYMBOL(sg_alloc_table); | |
b1adaf65 | 364 | |
efc42bc9 | 365 | /** |
89d8589c TU |
366 | * __sg_alloc_table_from_pages - Allocate and initialize an sg table from |
367 | * an array of pages | |
368 | * @sgt: The sg table header to use | |
369 | * @pages: Pointer to an array of page pointers | |
370 | * @n_pages: Number of pages in the pages array | |
371 | * @offset: Offset from start of the first page to the start of a buffer | |
372 | * @size: Number of valid bytes in the buffer (after offset) | |
373 | * @max_segment: Maximum size of a scatterlist node in bytes (page aligned) | |
374 | * @gfp_mask: GFP allocation mask | |
efc42bc9 TS |
375 | * |
376 | * Description: | |
377 | * Allocate and initialize an sg table from a list of pages. Contiguous | |
89d8589c TU |
378 | * ranges of the pages are squashed into a single scatterlist node up to the |
379 | * maximum size specified in @max_segment. An user may provide an offset at a | |
380 | * start and a size of valid data in a buffer specified by the page array. | |
381 | * The returned sg table is released by sg_free_table. | |
efc42bc9 TS |
382 | * |
383 | * Returns: | |
384 | * 0 on success, negative error on failure | |
385 | */ | |
89d8589c TU |
386 | int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, |
387 | unsigned int n_pages, unsigned int offset, | |
388 | unsigned long size, unsigned int max_segment, | |
389 | gfp_t gfp_mask) | |
efc42bc9 | 390 | { |
c125906b | 391 | unsigned int chunks, cur_page, seg_len, i; |
efc42bc9 TS |
392 | int ret; |
393 | struct scatterlist *s; | |
394 | ||
89d8589c TU |
395 | if (WARN_ON(!max_segment || offset_in_page(max_segment))) |
396 | return -EINVAL; | |
397 | ||
efc42bc9 TS |
398 | /* compute number of contiguous chunks */ |
399 | chunks = 1; | |
c125906b TU |
400 | seg_len = 0; |
401 | for (i = 1; i < n_pages; i++) { | |
402 | seg_len += PAGE_SIZE; | |
403 | if (seg_len >= max_segment || | |
404 | page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) { | |
405 | chunks++; | |
406 | seg_len = 0; | |
407 | } | |
408 | } | |
efc42bc9 TS |
409 | |
410 | ret = sg_alloc_table(sgt, chunks, gfp_mask); | |
411 | if (unlikely(ret)) | |
412 | return ret; | |
413 | ||
414 | /* merging chunks and putting them into the scatterlist */ | |
415 | cur_page = 0; | |
416 | for_each_sg(sgt->sgl, s, sgt->orig_nents, i) { | |
c125906b | 417 | unsigned int j, chunk_size; |
efc42bc9 TS |
418 | |
419 | /* look for the end of the current chunk */ | |
c125906b TU |
420 | seg_len = 0; |
421 | for (j = cur_page + 1; j < n_pages; j++) { | |
422 | seg_len += PAGE_SIZE; | |
423 | if (seg_len >= max_segment || | |
424 | page_to_pfn(pages[j]) != | |
efc42bc9 TS |
425 | page_to_pfn(pages[j - 1]) + 1) |
426 | break; | |
c125906b | 427 | } |
efc42bc9 TS |
428 | |
429 | chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; | |
c125906b TU |
430 | sg_set_page(s, pages[cur_page], |
431 | min_t(unsigned long, size, chunk_size), offset); | |
efc42bc9 TS |
432 | size -= chunk_size; |
433 | offset = 0; | |
434 | cur_page = j; | |
435 | } | |
436 | ||
437 | return 0; | |
438 | } | |
89d8589c TU |
439 | EXPORT_SYMBOL(__sg_alloc_table_from_pages); |
440 | ||
441 | /** | |
442 | * sg_alloc_table_from_pages - Allocate and initialize an sg table from | |
443 | * an array of pages | |
444 | * @sgt: The sg table header to use | |
445 | * @pages: Pointer to an array of page pointers | |
446 | * @n_pages: Number of pages in the pages array | |
447 | * @offset: Offset from start of the first page to the start of a buffer | |
448 | * @size: Number of valid bytes in the buffer (after offset) | |
449 | * @gfp_mask: GFP allocation mask | |
450 | * | |
451 | * Description: | |
452 | * Allocate and initialize an sg table from a list of pages. Contiguous | |
453 | * ranges of the pages are squashed into a single scatterlist node. A user | |
454 | * may provide an offset at a start and a size of valid data in a buffer | |
455 | * specified by the page array. The returned sg table is released by | |
456 | * sg_free_table. | |
457 | * | |
458 | * Returns: | |
459 | * 0 on success, negative error on failure | |
460 | */ | |
461 | int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, | |
462 | unsigned int n_pages, unsigned int offset, | |
463 | unsigned long size, gfp_t gfp_mask) | |
464 | { | |
465 | return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size, | |
466 | SCATTERLIST_MAX_SEGMENT, gfp_mask); | |
467 | } | |
efc42bc9 TS |
468 | EXPORT_SYMBOL(sg_alloc_table_from_pages); |
469 | ||
e80a0af4 BVA |
470 | #ifdef CONFIG_SGL_ALLOC |
471 | ||
472 | /** | |
473 | * sgl_alloc_order - allocate a scatterlist and its pages | |
474 | * @length: Length in bytes of the scatterlist. Must be at least one | |
475 | * @order: Second argument for alloc_pages() | |
476 | * @chainable: Whether or not to allocate an extra element in the scatterlist | |
477 | * for scatterlist chaining purposes | |
478 | * @gfp: Memory allocation flags | |
479 | * @nent_p: [out] Number of entries in the scatterlist that have pages | |
480 | * | |
481 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
482 | */ | |
483 | struct scatterlist *sgl_alloc_order(unsigned long long length, | |
484 | unsigned int order, bool chainable, | |
485 | gfp_t gfp, unsigned int *nent_p) | |
486 | { | |
487 | struct scatterlist *sgl, *sg; | |
488 | struct page *page; | |
489 | unsigned int nent, nalloc; | |
490 | u32 elem_len; | |
491 | ||
492 | nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); | |
493 | /* Check for integer overflow */ | |
494 | if (length > (nent << (PAGE_SHIFT + order))) | |
495 | return NULL; | |
496 | nalloc = nent; | |
497 | if (chainable) { | |
498 | /* Check for integer overflow */ | |
499 | if (nalloc + 1 < nalloc) | |
500 | return NULL; | |
501 | nalloc++; | |
502 | } | |
503 | sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), | |
504 | (gfp & ~GFP_DMA) | __GFP_ZERO); | |
505 | if (!sgl) | |
506 | return NULL; | |
507 | ||
8c7a8d1c | 508 | sg_init_table(sgl, nalloc); |
e80a0af4 BVA |
509 | sg = sgl; |
510 | while (length) { | |
511 | elem_len = min_t(u64, length, PAGE_SIZE << order); | |
512 | page = alloc_pages(gfp, order); | |
513 | if (!page) { | |
514 | sgl_free(sgl); | |
515 | return NULL; | |
516 | } | |
517 | ||
518 | sg_set_page(sg, page, elem_len, 0); | |
519 | length -= elem_len; | |
520 | sg = sg_next(sg); | |
521 | } | |
8c7a8d1c | 522 | WARN_ONCE(length, "length = %lld\n", length); |
e80a0af4 BVA |
523 | if (nent_p) |
524 | *nent_p = nent; | |
525 | return sgl; | |
526 | } | |
527 | EXPORT_SYMBOL(sgl_alloc_order); | |
528 | ||
529 | /** | |
530 | * sgl_alloc - allocate a scatterlist and its pages | |
531 | * @length: Length in bytes of the scatterlist | |
532 | * @gfp: Memory allocation flags | |
533 | * @nent_p: [out] Number of entries in the scatterlist | |
534 | * | |
535 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
536 | */ | |
537 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, | |
538 | unsigned int *nent_p) | |
539 | { | |
540 | return sgl_alloc_order(length, 0, false, gfp, nent_p); | |
541 | } | |
542 | EXPORT_SYMBOL(sgl_alloc); | |
543 | ||
544 | /** | |
8c7a8d1c | 545 | * sgl_free_n_order - free a scatterlist and its pages |
e80a0af4 | 546 | * @sgl: Scatterlist with one or more elements |
8c7a8d1c | 547 | * @nents: Maximum number of elements to free |
e80a0af4 | 548 | * @order: Second argument for __free_pages() |
8c7a8d1c BVA |
549 | * |
550 | * Notes: | |
551 | * - If several scatterlists have been chained and each chain element is | |
552 | * freed separately then it's essential to set nents correctly to avoid that a | |
553 | * page would get freed twice. | |
554 | * - All pages in a chained scatterlist can be freed at once by setting @nents | |
555 | * to a high number. | |
e80a0af4 | 556 | */ |
8c7a8d1c | 557 | void sgl_free_n_order(struct scatterlist *sgl, int nents, int order) |
e80a0af4 BVA |
558 | { |
559 | struct scatterlist *sg; | |
560 | struct page *page; | |
8c7a8d1c | 561 | int i; |
e80a0af4 | 562 | |
8c7a8d1c BVA |
563 | for_each_sg(sgl, sg, nents, i) { |
564 | if (!sg) | |
565 | break; | |
e80a0af4 BVA |
566 | page = sg_page(sg); |
567 | if (page) | |
568 | __free_pages(page, order); | |
569 | } | |
570 | kfree(sgl); | |
571 | } | |
8c7a8d1c BVA |
572 | EXPORT_SYMBOL(sgl_free_n_order); |
573 | ||
574 | /** | |
575 | * sgl_free_order - free a scatterlist and its pages | |
576 | * @sgl: Scatterlist with one or more elements | |
577 | * @order: Second argument for __free_pages() | |
578 | */ | |
579 | void sgl_free_order(struct scatterlist *sgl, int order) | |
580 | { | |
581 | sgl_free_n_order(sgl, INT_MAX, order); | |
582 | } | |
e80a0af4 BVA |
583 | EXPORT_SYMBOL(sgl_free_order); |
584 | ||
585 | /** | |
586 | * sgl_free - free a scatterlist and its pages | |
587 | * @sgl: Scatterlist with one or more elements | |
588 | */ | |
589 | void sgl_free(struct scatterlist *sgl) | |
590 | { | |
591 | sgl_free_order(sgl, 0); | |
592 | } | |
593 | EXPORT_SYMBOL(sgl_free); | |
594 | ||
595 | #endif /* CONFIG_SGL_ALLOC */ | |
596 | ||
a321e91b ID |
597 | void __sg_page_iter_start(struct sg_page_iter *piter, |
598 | struct scatterlist *sglist, unsigned int nents, | |
599 | unsigned long pgoffset) | |
600 | { | |
601 | piter->__pg_advance = 0; | |
602 | piter->__nents = nents; | |
603 | ||
a321e91b ID |
604 | piter->sg = sglist; |
605 | piter->sg_pgoffset = pgoffset; | |
606 | } | |
607 | EXPORT_SYMBOL(__sg_page_iter_start); | |
608 | ||
609 | static int sg_page_count(struct scatterlist *sg) | |
610 | { | |
611 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; | |
612 | } | |
613 | ||
614 | bool __sg_page_iter_next(struct sg_page_iter *piter) | |
615 | { | |
616 | if (!piter->__nents || !piter->sg) | |
617 | return false; | |
618 | ||
619 | piter->sg_pgoffset += piter->__pg_advance; | |
620 | piter->__pg_advance = 1; | |
621 | ||
622 | while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { | |
623 | piter->sg_pgoffset -= sg_page_count(piter->sg); | |
624 | piter->sg = sg_next(piter->sg); | |
625 | if (!--piter->__nents || !piter->sg) | |
626 | return false; | |
627 | } | |
a321e91b ID |
628 | |
629 | return true; | |
630 | } | |
631 | EXPORT_SYMBOL(__sg_page_iter_next); | |
632 | ||
137d3edb TH |
633 | /** |
634 | * sg_miter_start - start mapping iteration over a sg list | |
635 | * @miter: sg mapping iter to be started | |
636 | * @sgl: sg list to iterate over | |
637 | * @nents: number of sg entries | |
638 | * | |
639 | * Description: | |
640 | * Starts mapping iterator @miter. | |
641 | * | |
642 | * Context: | |
643 | * Don't care. | |
644 | */ | |
645 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
646 | unsigned int nents, unsigned int flags) | |
647 | { | |
648 | memset(miter, 0, sizeof(struct sg_mapping_iter)); | |
649 | ||
4225fc85 | 650 | __sg_page_iter_start(&miter->piter, sgl, nents, 0); |
6de7e356 | 651 | WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); |
137d3edb TH |
652 | miter->__flags = flags; |
653 | } | |
654 | EXPORT_SYMBOL(sg_miter_start); | |
655 | ||
11052004 AM |
656 | static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) |
657 | { | |
658 | if (!miter->__remaining) { | |
659 | struct scatterlist *sg; | |
660 | unsigned long pgoffset; | |
661 | ||
662 | if (!__sg_page_iter_next(&miter->piter)) | |
663 | return false; | |
664 | ||
665 | sg = miter->piter.sg; | |
666 | pgoffset = miter->piter.sg_pgoffset; | |
667 | ||
668 | miter->__offset = pgoffset ? 0 : sg->offset; | |
669 | miter->__remaining = sg->offset + sg->length - | |
670 | (pgoffset << PAGE_SHIFT) - miter->__offset; | |
671 | miter->__remaining = min_t(unsigned long, miter->__remaining, | |
672 | PAGE_SIZE - miter->__offset); | |
673 | } | |
674 | ||
675 | return true; | |
676 | } | |
677 | ||
df642cea AM |
678 | /** |
679 | * sg_miter_skip - reposition mapping iterator | |
680 | * @miter: sg mapping iter to be skipped | |
681 | * @offset: number of bytes to plus the current location | |
682 | * | |
683 | * Description: | |
684 | * Sets the offset of @miter to its current location plus @offset bytes. | |
685 | * If mapping iterator @miter has been proceeded by sg_miter_next(), this | |
686 | * stops @miter. | |
687 | * | |
688 | * Context: | |
689 | * Don't care if @miter is stopped, or not proceeded yet. | |
690 | * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set. | |
691 | * | |
692 | * Returns: | |
693 | * true if @miter contains the valid mapping. false if end of sg | |
694 | * list is reached. | |
695 | */ | |
0d6077f8 | 696 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) |
df642cea AM |
697 | { |
698 | sg_miter_stop(miter); | |
699 | ||
700 | while (offset) { | |
701 | off_t consumed; | |
702 | ||
703 | if (!sg_miter_get_next_page(miter)) | |
704 | return false; | |
705 | ||
706 | consumed = min_t(off_t, offset, miter->__remaining); | |
707 | miter->__offset += consumed; | |
708 | miter->__remaining -= consumed; | |
709 | offset -= consumed; | |
710 | } | |
711 | ||
712 | return true; | |
713 | } | |
0d6077f8 | 714 | EXPORT_SYMBOL(sg_miter_skip); |
df642cea | 715 | |
137d3edb TH |
716 | /** |
717 | * sg_miter_next - proceed mapping iterator to the next mapping | |
718 | * @miter: sg mapping iter to proceed | |
719 | * | |
720 | * Description: | |
8290e2d2 TH |
721 | * Proceeds @miter to the next mapping. @miter should have been started |
722 | * using sg_miter_start(). On successful return, @miter->page, | |
723 | * @miter->addr and @miter->length point to the current mapping. | |
137d3edb TH |
724 | * |
725 | * Context: | |
8290e2d2 TH |
726 | * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled |
727 | * till @miter is stopped. May sleep if !SG_MITER_ATOMIC. | |
137d3edb TH |
728 | * |
729 | * Returns: | |
730 | * true if @miter contains the next mapping. false if end of sg | |
731 | * list is reached. | |
732 | */ | |
733 | bool sg_miter_next(struct sg_mapping_iter *miter) | |
734 | { | |
137d3edb TH |
735 | sg_miter_stop(miter); |
736 | ||
4225fc85 ID |
737 | /* |
738 | * Get to the next page if necessary. | |
739 | * __remaining, __offset is adjusted by sg_miter_stop | |
740 | */ | |
11052004 AM |
741 | if (!sg_miter_get_next_page(miter)) |
742 | return false; | |
137d3edb | 743 | |
2db76d7c | 744 | miter->page = sg_page_iter_page(&miter->piter); |
4225fc85 | 745 | miter->consumed = miter->length = miter->__remaining; |
137d3edb TH |
746 | |
747 | if (miter->__flags & SG_MITER_ATOMIC) | |
4225fc85 | 748 | miter->addr = kmap_atomic(miter->page) + miter->__offset; |
137d3edb | 749 | else |
4225fc85 | 750 | miter->addr = kmap(miter->page) + miter->__offset; |
137d3edb TH |
751 | |
752 | return true; | |
753 | } | |
754 | EXPORT_SYMBOL(sg_miter_next); | |
755 | ||
756 | /** | |
757 | * sg_miter_stop - stop mapping iteration | |
758 | * @miter: sg mapping iter to be stopped | |
759 | * | |
760 | * Description: | |
761 | * Stops mapping iterator @miter. @miter should have been started | |
4ba6a2b2 MY |
762 | * using sg_miter_start(). A stopped iteration can be resumed by |
763 | * calling sg_miter_next() on it. This is useful when resources (kmap) | |
764 | * need to be released during iteration. | |
137d3edb TH |
765 | * |
766 | * Context: | |
8290e2d2 TH |
767 | * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care |
768 | * otherwise. | |
137d3edb TH |
769 | */ |
770 | void sg_miter_stop(struct sg_mapping_iter *miter) | |
771 | { | |
772 | WARN_ON(miter->consumed > miter->length); | |
773 | ||
774 | /* drop resources from the last iteration */ | |
775 | if (miter->addr) { | |
776 | miter->__offset += miter->consumed; | |
4225fc85 | 777 | miter->__remaining -= miter->consumed; |
137d3edb | 778 | |
3d77b50c ML |
779 | if ((miter->__flags & SG_MITER_TO_SG) && |
780 | !PageSlab(miter->page)) | |
6de7e356 SAS |
781 | flush_kernel_dcache_page(miter->page); |
782 | ||
137d3edb | 783 | if (miter->__flags & SG_MITER_ATOMIC) { |
8290e2d2 | 784 | WARN_ON_ONCE(preemptible()); |
c3eede8e | 785 | kunmap_atomic(miter->addr); |
137d3edb | 786 | } else |
f652c521 | 787 | kunmap(miter->page); |
137d3edb TH |
788 | |
789 | miter->page = NULL; | |
790 | miter->addr = NULL; | |
791 | miter->length = 0; | |
792 | miter->consumed = 0; | |
793 | } | |
794 | } | |
795 | EXPORT_SYMBOL(sg_miter_stop); | |
796 | ||
b1adaf65 FT |
797 | /** |
798 | * sg_copy_buffer - Copy data between a linear buffer and an SG list | |
799 | * @sgl: The SG list | |
800 | * @nents: Number of SG entries | |
801 | * @buf: Where to copy from | |
802 | * @buflen: The number of bytes to copy | |
df642cea AM |
803 | * @skip: Number of bytes to skip before copying |
804 | * @to_buffer: transfer direction (true == from an sg list to a | |
805 | * buffer, false == from a buffer to an sg list | |
b1adaf65 FT |
806 | * |
807 | * Returns the number of copied bytes. | |
808 | * | |
809 | **/ | |
386ecb12 DG |
810 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
811 | size_t buflen, off_t skip, bool to_buffer) | |
b1adaf65 | 812 | { |
137d3edb TH |
813 | unsigned int offset = 0; |
814 | struct sg_mapping_iter miter; | |
6de7e356 SAS |
815 | unsigned int sg_flags = SG_MITER_ATOMIC; |
816 | ||
817 | if (to_buffer) | |
818 | sg_flags |= SG_MITER_FROM_SG; | |
819 | else | |
820 | sg_flags |= SG_MITER_TO_SG; | |
137d3edb | 821 | |
6de7e356 | 822 | sg_miter_start(&miter, sgl, nents, sg_flags); |
137d3edb | 823 | |
df642cea AM |
824 | if (!sg_miter_skip(&miter, skip)) |
825 | return false; | |
826 | ||
1d5210ef | 827 | while ((offset < buflen) && sg_miter_next(&miter)) { |
137d3edb TH |
828 | unsigned int len; |
829 | ||
830 | len = min(miter.length, buflen - offset); | |
831 | ||
832 | if (to_buffer) | |
833 | memcpy(buf + offset, miter.addr, len); | |
6de7e356 | 834 | else |
137d3edb | 835 | memcpy(miter.addr, buf + offset, len); |
b1adaf65 | 836 | |
137d3edb | 837 | offset += len; |
b1adaf65 FT |
838 | } |
839 | ||
137d3edb TH |
840 | sg_miter_stop(&miter); |
841 | ||
842 | return offset; | |
b1adaf65 | 843 | } |
386ecb12 | 844 | EXPORT_SYMBOL(sg_copy_buffer); |
b1adaf65 FT |
845 | |
846 | /** | |
847 | * sg_copy_from_buffer - Copy from a linear buffer to an SG list | |
848 | * @sgl: The SG list | |
849 | * @nents: Number of SG entries | |
850 | * @buf: Where to copy from | |
851 | * @buflen: The number of bytes to copy | |
852 | * | |
853 | * Returns the number of copied bytes. | |
854 | * | |
855 | **/ | |
856 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 857 | const void *buf, size_t buflen) |
b1adaf65 | 858 | { |
2a1bf8f9 | 859 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); |
b1adaf65 FT |
860 | } |
861 | EXPORT_SYMBOL(sg_copy_from_buffer); | |
862 | ||
863 | /** | |
864 | * sg_copy_to_buffer - Copy from an SG list to a linear buffer | |
865 | * @sgl: The SG list | |
866 | * @nents: Number of SG entries | |
867 | * @buf: Where to copy to | |
868 | * @buflen: The number of bytes to copy | |
869 | * | |
870 | * Returns the number of copied bytes. | |
871 | * | |
872 | **/ | |
873 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
874 | void *buf, size_t buflen) | |
875 | { | |
df642cea | 876 | return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); |
b1adaf65 FT |
877 | } |
878 | EXPORT_SYMBOL(sg_copy_to_buffer); | |
df642cea AM |
879 | |
880 | /** | |
881 | * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list | |
882 | * @sgl: The SG list | |
883 | * @nents: Number of SG entries | |
884 | * @buf: Where to copy from | |
df642cea | 885 | * @buflen: The number of bytes to copy |
4dc7daf8 | 886 | * @skip: Number of bytes to skip before copying |
df642cea AM |
887 | * |
888 | * Returns the number of copied bytes. | |
889 | * | |
890 | **/ | |
891 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 892 | const void *buf, size_t buflen, off_t skip) |
df642cea | 893 | { |
2a1bf8f9 | 894 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); |
df642cea AM |
895 | } |
896 | EXPORT_SYMBOL(sg_pcopy_from_buffer); | |
897 | ||
898 | /** | |
899 | * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer | |
900 | * @sgl: The SG list | |
901 | * @nents: Number of SG entries | |
902 | * @buf: Where to copy to | |
df642cea | 903 | * @buflen: The number of bytes to copy |
4dc7daf8 | 904 | * @skip: Number of bytes to skip before copying |
df642cea AM |
905 | * |
906 | * Returns the number of copied bytes. | |
907 | * | |
908 | **/ | |
909 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
910 | void *buf, size_t buflen, off_t skip) | |
911 | { | |
912 | return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); | |
913 | } | |
914 | EXPORT_SYMBOL(sg_pcopy_to_buffer); | |
0945e569 JT |
915 | |
916 | /** | |
917 | * sg_zero_buffer - Zero-out a part of a SG list | |
918 | * @sgl: The SG list | |
919 | * @nents: Number of SG entries | |
920 | * @buflen: The number of bytes to zero out | |
921 | * @skip: Number of bytes to skip before zeroing | |
922 | * | |
923 | * Returns the number of bytes zeroed. | |
924 | **/ | |
925 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, | |
926 | size_t buflen, off_t skip) | |
927 | { | |
928 | unsigned int offset = 0; | |
929 | struct sg_mapping_iter miter; | |
930 | unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; | |
931 | ||
932 | sg_miter_start(&miter, sgl, nents, sg_flags); | |
933 | ||
934 | if (!sg_miter_skip(&miter, skip)) | |
935 | return false; | |
936 | ||
937 | while (offset < buflen && sg_miter_next(&miter)) { | |
938 | unsigned int len; | |
939 | ||
940 | len = min(miter.length, buflen - offset); | |
941 | memset(miter.addr, 0, len); | |
942 | ||
943 | offset += len; | |
944 | } | |
945 | ||
946 | sg_miter_stop(&miter); | |
947 | return offset; | |
948 | } | |
949 | EXPORT_SYMBOL(sg_zero_buffer); |