blob: 004fc70fc56a3d06947f9e89c60e40e272ce551c
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 | */ |
9 | #include <linux/export.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/scatterlist.h> |
12 | #include <linux/highmem.h> |
13 | #include <linux/kmemleak.h> |
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 | |
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 | { |
52 | int nents; |
53 | for (nents = 0; sg; sg = sg_next(sg)) |
54 | nents++; |
55 | return nents; |
56 | } |
57 | EXPORT_SYMBOL(sg_nents); |
58 | |
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); |
91 | |
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 | { |
108 | struct scatterlist *sg, *ret = NULL; |
109 | unsigned int i; |
110 | |
111 | for_each_sg(sgl, sg, nents, i) |
112 | ret = sg; |
113 | |
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); |
135 | #ifdef CONFIG_DEBUG_SG |
136 | { |
137 | unsigned int i; |
138 | for (i = 0; i < nents; i++) |
139 | sgl[i].sg_magic = SG_MAGIC; |
140 | } |
141 | #endif |
142 | sg_mark_end(&sgl[nents - 1]); |
143 | } |
144 | EXPORT_SYMBOL(sg_init_table); |
145 | |
146 | /** |
147 | * sg_init_one - Initialize a single entry sg list |
148 | * @sg: SG entry |
149 | * @buf: Virtual address for IO |
150 | * @buflen: IO length |
151 | * |
152 | **/ |
153 | void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) |
154 | { |
155 | sg_init_table(sg, 1); |
156 | sg_set_buf(sg, buf, buflen); |
157 | } |
158 | EXPORT_SYMBOL(sg_init_one); |
159 | |
160 | /* |
161 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree |
162 | * helpers. |
163 | */ |
164 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) |
165 | { |
166 | if (nents == SG_MAX_SINGLE_ALLOC) { |
167 | /* |
168 | * Kmemleak doesn't track page allocations as they are not |
169 | * commonly used (in a raw form) for kernel data structures. |
170 | * As we chain together a list of pages and then a normal |
171 | * kmalloc (tracked by kmemleak), in order to for that last |
172 | * allocation not to become decoupled (and thus a |
173 | * false-positive) we need to inform kmemleak of all the |
174 | * intermediate allocations. |
175 | */ |
176 | void *ptr = (void *) __get_free_page(gfp_mask); |
177 | kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); |
178 | return ptr; |
179 | } else |
180 | return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); |
181 | } |
182 | |
183 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) |
184 | { |
185 | if (nents == SG_MAX_SINGLE_ALLOC) { |
186 | kmemleak_free(sg); |
187 | free_page((unsigned long) sg); |
188 | } else |
189 | kfree(sg); |
190 | } |
191 | |
192 | /** |
193 | * __sg_free_table - Free a previously mapped sg table |
194 | * @table: The sg table header to use |
195 | * @max_ents: The maximum number of entries per single scatterlist |
196 | * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk |
197 | * @free_fn: Free function |
198 | * |
199 | * Description: |
200 | * Free an sg table previously allocated and setup with |
201 | * __sg_alloc_table(). The @max_ents value must be identical to |
202 | * that previously used with __sg_alloc_table(). |
203 | * |
204 | **/ |
205 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
206 | bool skip_first_chunk, sg_free_fn *free_fn) |
207 | { |
208 | struct scatterlist *sgl, *next; |
209 | |
210 | if (unlikely(!table->sgl)) |
211 | return; |
212 | |
213 | sgl = table->sgl; |
214 | while (table->orig_nents) { |
215 | unsigned int alloc_size = table->orig_nents; |
216 | unsigned int sg_size; |
217 | |
218 | /* |
219 | * If we have more than max_ents segments left, |
220 | * then assign 'next' to the sg table after the current one. |
221 | * sg_size is then one less than alloc size, since the last |
222 | * element is the chain pointer. |
223 | */ |
224 | if (alloc_size > max_ents) { |
225 | next = sg_chain_ptr(&sgl[max_ents - 1]); |
226 | alloc_size = max_ents; |
227 | sg_size = alloc_size - 1; |
228 | } else { |
229 | sg_size = alloc_size; |
230 | next = NULL; |
231 | } |
232 | |
233 | table->orig_nents -= sg_size; |
234 | if (skip_first_chunk) |
235 | skip_first_chunk = false; |
236 | else |
237 | free_fn(sgl, alloc_size); |
238 | sgl = next; |
239 | } |
240 | |
241 | table->sgl = NULL; |
242 | } |
243 | EXPORT_SYMBOL(__sg_free_table); |
244 | |
245 | /** |
246 | * sg_free_table - Free a previously allocated sg table |
247 | * @table: The mapped sg table header |
248 | * |
249 | **/ |
250 | void sg_free_table(struct sg_table *table) |
251 | { |
252 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
253 | } |
254 | EXPORT_SYMBOL(sg_free_table); |
255 | |
256 | /** |
257 | * __sg_alloc_table - Allocate and initialize an sg table with given allocator |
258 | * @table: The sg table header to use |
259 | * @nents: Number of entries in sg list |
260 | * @max_ents: The maximum number of entries the allocator returns per call |
261 | * @gfp_mask: GFP allocation mask |
262 | * @alloc_fn: Allocator to use |
263 | * |
264 | * Description: |
265 | * This function returns a @table @nents long. The allocator is |
266 | * defined to return scatterlist chunks of maximum size @max_ents. |
267 | * Thus if @nents is bigger than @max_ents, the scatterlists will be |
268 | * chained in units of @max_ents. |
269 | * |
270 | * Notes: |
271 | * If this function returns non-0 (eg failure), the caller must call |
272 | * __sg_free_table() to cleanup any leftover allocations. |
273 | * |
274 | **/ |
275 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
276 | unsigned int max_ents, struct scatterlist *first_chunk, |
277 | gfp_t gfp_mask, sg_alloc_fn *alloc_fn) |
278 | { |
279 | struct scatterlist *sg, *prv; |
280 | unsigned int left; |
281 | |
282 | memset(table, 0, sizeof(*table)); |
283 | |
284 | if (nents == 0) |
285 | return -EINVAL; |
286 | #ifndef CONFIG_ARCH_HAS_SG_CHAIN |
287 | if (WARN_ON_ONCE(nents > max_ents)) |
288 | return -EINVAL; |
289 | #endif |
290 | |
291 | left = nents; |
292 | prv = NULL; |
293 | do { |
294 | unsigned int sg_size, alloc_size = left; |
295 | |
296 | if (alloc_size > max_ents) { |
297 | alloc_size = max_ents; |
298 | sg_size = alloc_size - 1; |
299 | } else |
300 | sg_size = alloc_size; |
301 | |
302 | left -= sg_size; |
303 | |
304 | if (first_chunk) { |
305 | sg = first_chunk; |
306 | first_chunk = NULL; |
307 | } else { |
308 | sg = alloc_fn(alloc_size, gfp_mask); |
309 | } |
310 | if (unlikely(!sg)) { |
311 | /* |
312 | * Adjust entry count to reflect that the last |
313 | * entry of the previous table won't be used for |
314 | * linkage. Without this, sg_kfree() may get |
315 | * confused. |
316 | */ |
317 | if (prv) |
318 | table->nents = ++table->orig_nents; |
319 | |
320 | return -ENOMEM; |
321 | } |
322 | |
323 | sg_init_table(sg, alloc_size); |
324 | table->nents = table->orig_nents += sg_size; |
325 | |
326 | /* |
327 | * If this is the first mapping, assign the sg table header. |
328 | * If this is not the first mapping, chain previous part. |
329 | */ |
330 | if (prv) |
331 | sg_chain(prv, max_ents, sg); |
332 | else |
333 | table->sgl = sg; |
334 | |
335 | /* |
336 | * If no more entries after this one, mark the end |
337 | */ |
338 | if (!left) |
339 | sg_mark_end(&sg[sg_size - 1]); |
340 | |
341 | prv = sg; |
342 | } while (left); |
343 | |
344 | return 0; |
345 | } |
346 | EXPORT_SYMBOL(__sg_alloc_table); |
347 | |
348 | /** |
349 | * sg_alloc_table - Allocate and initialize an sg table |
350 | * @table: The sg table header to use |
351 | * @nents: Number of entries in sg list |
352 | * @gfp_mask: GFP allocation mask |
353 | * |
354 | * Description: |
355 | * Allocate and initialize an sg table. If @nents@ is larger than |
356 | * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. |
357 | * |
358 | **/ |
359 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) |
360 | { |
361 | int ret; |
362 | |
363 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
364 | NULL, gfp_mask, sg_kmalloc); |
365 | if (unlikely(ret)) |
366 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
367 | |
368 | return ret; |
369 | } |
370 | EXPORT_SYMBOL(sg_alloc_table); |
371 | |
372 | /** |
373 | * sg_alloc_table_from_pages - Allocate and initialize an sg table from |
374 | * an array of pages |
375 | * @sgt: The sg table header to use |
376 | * @pages: Pointer to an array of page pointers |
377 | * @n_pages: Number of pages in the pages array |
378 | * @offset: Offset from start of the first page to the start of a buffer |
379 | * @size: Number of valid bytes in the buffer (after offset) |
380 | * @gfp_mask: GFP allocation mask |
381 | * |
382 | * Description: |
383 | * Allocate and initialize an sg table from a list of pages. Contiguous |
384 | * ranges of the pages are squashed into a single scatterlist node. A user |
385 | * may provide an offset at a start and a size of valid data in a buffer |
386 | * specified by the page array. The returned sg table is released by |
387 | * sg_free_table. |
388 | * |
389 | * Returns: |
390 | * 0 on success, negative error on failure |
391 | */ |
392 | int sg_alloc_table_from_pages(struct sg_table *sgt, |
393 | struct page **pages, unsigned int n_pages, |
394 | unsigned long offset, unsigned long size, |
395 | gfp_t gfp_mask) |
396 | { |
397 | unsigned int chunks; |
398 | unsigned int i; |
399 | unsigned int cur_page; |
400 | int ret; |
401 | struct scatterlist *s; |
402 | |
403 | /* compute number of contiguous chunks */ |
404 | chunks = 1; |
405 | for (i = 1; i < n_pages; ++i) |
406 | if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) |
407 | ++chunks; |
408 | |
409 | ret = sg_alloc_table(sgt, chunks, gfp_mask); |
410 | if (unlikely(ret)) |
411 | return ret; |
412 | |
413 | /* merging chunks and putting them into the scatterlist */ |
414 | cur_page = 0; |
415 | for_each_sg(sgt->sgl, s, sgt->orig_nents, i) { |
416 | unsigned long chunk_size; |
417 | unsigned int j; |
418 | |
419 | /* look for the end of the current chunk */ |
420 | for (j = cur_page + 1; j < n_pages; ++j) |
421 | if (page_to_pfn(pages[j]) != |
422 | page_to_pfn(pages[j - 1]) + 1) |
423 | break; |
424 | |
425 | chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; |
426 | sg_set_page(s, pages[cur_page], min(size, chunk_size), offset); |
427 | size -= chunk_size; |
428 | offset = 0; |
429 | cur_page = j; |
430 | } |
431 | |
432 | return 0; |
433 | } |
434 | EXPORT_SYMBOL(sg_alloc_table_from_pages); |
435 | |
436 | void __sg_page_iter_start(struct sg_page_iter *piter, |
437 | struct scatterlist *sglist, unsigned int nents, |
438 | unsigned long pgoffset) |
439 | { |
440 | piter->__pg_advance = 0; |
441 | piter->__nents = nents; |
442 | |
443 | piter->sg = sglist; |
444 | piter->sg_pgoffset = pgoffset; |
445 | } |
446 | EXPORT_SYMBOL(__sg_page_iter_start); |
447 | |
448 | static int sg_page_count(struct scatterlist *sg) |
449 | { |
450 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; |
451 | } |
452 | |
453 | bool __sg_page_iter_next(struct sg_page_iter *piter) |
454 | { |
455 | if (!piter->__nents || !piter->sg) |
456 | return false; |
457 | |
458 | piter->sg_pgoffset += piter->__pg_advance; |
459 | piter->__pg_advance = 1; |
460 | |
461 | while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { |
462 | piter->sg_pgoffset -= sg_page_count(piter->sg); |
463 | piter->sg = sg_next(piter->sg); |
464 | if (!--piter->__nents || !piter->sg) |
465 | return false; |
466 | } |
467 | |
468 | return true; |
469 | } |
470 | EXPORT_SYMBOL(__sg_page_iter_next); |
471 | |
472 | /** |
473 | * sg_miter_start - start mapping iteration over a sg list |
474 | * @miter: sg mapping iter to be started |
475 | * @sgl: sg list to iterate over |
476 | * @nents: number of sg entries |
477 | * |
478 | * Description: |
479 | * Starts mapping iterator @miter. |
480 | * |
481 | * Context: |
482 | * Don't care. |
483 | */ |
484 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, |
485 | unsigned int nents, unsigned int flags) |
486 | { |
487 | memset(miter, 0, sizeof(struct sg_mapping_iter)); |
488 | |
489 | __sg_page_iter_start(&miter->piter, sgl, nents, 0); |
490 | WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); |
491 | miter->__flags = flags; |
492 | } |
493 | EXPORT_SYMBOL(sg_miter_start); |
494 | |
495 | static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) |
496 | { |
497 | if (!miter->__remaining) { |
498 | struct scatterlist *sg; |
499 | unsigned long pgoffset; |
500 | |
501 | if (!__sg_page_iter_next(&miter->piter)) |
502 | return false; |
503 | |
504 | sg = miter->piter.sg; |
505 | pgoffset = miter->piter.sg_pgoffset; |
506 | |
507 | miter->__offset = pgoffset ? 0 : sg->offset; |
508 | miter->__remaining = sg->offset + sg->length - |
509 | (pgoffset << PAGE_SHIFT) - miter->__offset; |
510 | miter->__remaining = min_t(unsigned long, miter->__remaining, |
511 | PAGE_SIZE - miter->__offset); |
512 | } |
513 | |
514 | return true; |
515 | } |
516 | |
517 | /** |
518 | * sg_miter_skip - reposition mapping iterator |
519 | * @miter: sg mapping iter to be skipped |
520 | * @offset: number of bytes to plus the current location |
521 | * |
522 | * Description: |
523 | * Sets the offset of @miter to its current location plus @offset bytes. |
524 | * If mapping iterator @miter has been proceeded by sg_miter_next(), this |
525 | * stops @miter. |
526 | * |
527 | * Context: |
528 | * Don't care if @miter is stopped, or not proceeded yet. |
529 | * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set. |
530 | * |
531 | * Returns: |
532 | * true if @miter contains the valid mapping. false if end of sg |
533 | * list is reached. |
534 | */ |
535 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) |
536 | { |
537 | sg_miter_stop(miter); |
538 | |
539 | while (offset) { |
540 | off_t consumed; |
541 | |
542 | if (!sg_miter_get_next_page(miter)) |
543 | return false; |
544 | |
545 | consumed = min_t(off_t, offset, miter->__remaining); |
546 | miter->__offset += consumed; |
547 | miter->__remaining -= consumed; |
548 | offset -= consumed; |
549 | } |
550 | |
551 | return true; |
552 | } |
553 | EXPORT_SYMBOL(sg_miter_skip); |
554 | |
555 | /** |
556 | * sg_miter_next - proceed mapping iterator to the next mapping |
557 | * @miter: sg mapping iter to proceed |
558 | * |
559 | * Description: |
560 | * Proceeds @miter to the next mapping. @miter should have been started |
561 | * using sg_miter_start(). On successful return, @miter->page, |
562 | * @miter->addr and @miter->length point to the current mapping. |
563 | * |
564 | * Context: |
565 | * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled |
566 | * till @miter is stopped. May sleep if !SG_MITER_ATOMIC. |
567 | * |
568 | * Returns: |
569 | * true if @miter contains the next mapping. false if end of sg |
570 | * list is reached. |
571 | */ |
572 | bool sg_miter_next(struct sg_mapping_iter *miter) |
573 | { |
574 | sg_miter_stop(miter); |
575 | |
576 | /* |
577 | * Get to the next page if necessary. |
578 | * __remaining, __offset is adjusted by sg_miter_stop |
579 | */ |
580 | if (!sg_miter_get_next_page(miter)) |
581 | return false; |
582 | |
583 | miter->page = sg_page_iter_page(&miter->piter); |
584 | miter->consumed = miter->length = miter->__remaining; |
585 | |
586 | if (miter->__flags & SG_MITER_ATOMIC) |
587 | miter->addr = kmap_atomic(miter->page) + miter->__offset; |
588 | else |
589 | miter->addr = kmap(miter->page) + miter->__offset; |
590 | |
591 | return true; |
592 | } |
593 | EXPORT_SYMBOL(sg_miter_next); |
594 | |
595 | /** |
596 | * sg_miter_stop - stop mapping iteration |
597 | * @miter: sg mapping iter to be stopped |
598 | * |
599 | * Description: |
600 | * Stops mapping iterator @miter. @miter should have been started |
601 | * using sg_miter_start(). A stopped iteration can be resumed by |
602 | * calling sg_miter_next() on it. This is useful when resources (kmap) |
603 | * need to be released during iteration. |
604 | * |
605 | * Context: |
606 | * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care |
607 | * otherwise. |
608 | */ |
609 | void sg_miter_stop(struct sg_mapping_iter *miter) |
610 | { |
611 | WARN_ON(miter->consumed > miter->length); |
612 | |
613 | /* drop resources from the last iteration */ |
614 | if (miter->addr) { |
615 | miter->__offset += miter->consumed; |
616 | miter->__remaining -= miter->consumed; |
617 | |
618 | if ((miter->__flags & SG_MITER_TO_SG) && |
619 | !PageSlab(miter->page)) |
620 | flush_kernel_dcache_page(miter->page); |
621 | |
622 | if (miter->__flags & SG_MITER_ATOMIC) { |
623 | WARN_ON_ONCE(preemptible()); |
624 | kunmap_atomic(miter->addr); |
625 | } else |
626 | kunmap(miter->page); |
627 | |
628 | miter->page = NULL; |
629 | miter->addr = NULL; |
630 | miter->length = 0; |
631 | miter->consumed = 0; |
632 | } |
633 | } |
634 | EXPORT_SYMBOL(sg_miter_stop); |
635 | |
636 | /** |
637 | * sg_copy_buffer - Copy data between a linear buffer and an SG list |
638 | * @sgl: The SG list |
639 | * @nents: Number of SG entries |
640 | * @buf: Where to copy from |
641 | * @buflen: The number of bytes to copy |
642 | * @skip: Number of bytes to skip before copying |
643 | * @to_buffer: transfer direction (true == from an sg list to a |
644 | * buffer, false == from a buffer to an sg list |
645 | * |
646 | * Returns the number of copied bytes. |
647 | * |
648 | **/ |
649 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
650 | size_t buflen, off_t skip, bool to_buffer) |
651 | { |
652 | unsigned int offset = 0; |
653 | struct sg_mapping_iter miter; |
654 | unsigned long flags; |
655 | unsigned int sg_flags = SG_MITER_ATOMIC; |
656 | |
657 | if (to_buffer) |
658 | sg_flags |= SG_MITER_FROM_SG; |
659 | else |
660 | sg_flags |= SG_MITER_TO_SG; |
661 | |
662 | sg_miter_start(&miter, sgl, nents, sg_flags); |
663 | |
664 | if (!sg_miter_skip(&miter, skip)) |
665 | return false; |
666 | |
667 | local_irq_save(flags); |
668 | |
669 | while (sg_miter_next(&miter) && offset < buflen) { |
670 | unsigned int len; |
671 | |
672 | len = min(miter.length, buflen - offset); |
673 | |
674 | if (to_buffer) |
675 | memcpy(buf + offset, miter.addr, len); |
676 | else |
677 | memcpy(miter.addr, buf + offset, len); |
678 | |
679 | offset += len; |
680 | } |
681 | |
682 | sg_miter_stop(&miter); |
683 | |
684 | local_irq_restore(flags); |
685 | return offset; |
686 | } |
687 | EXPORT_SYMBOL(sg_copy_buffer); |
688 | |
689 | /** |
690 | * sg_copy_from_buffer - Copy from a linear buffer to an SG list |
691 | * @sgl: The SG list |
692 | * @nents: Number of SG entries |
693 | * @buf: Where to copy from |
694 | * @buflen: The number of bytes to copy |
695 | * |
696 | * Returns the number of copied bytes. |
697 | * |
698 | **/ |
699 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
700 | const void *buf, size_t buflen) |
701 | { |
702 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); |
703 | } |
704 | EXPORT_SYMBOL(sg_copy_from_buffer); |
705 | |
706 | /** |
707 | * sg_copy_to_buffer - Copy from an SG list to a linear buffer |
708 | * @sgl: The SG list |
709 | * @nents: Number of SG entries |
710 | * @buf: Where to copy to |
711 | * @buflen: The number of bytes to copy |
712 | * |
713 | * Returns the number of copied bytes. |
714 | * |
715 | **/ |
716 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
717 | void *buf, size_t buflen) |
718 | { |
719 | return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); |
720 | } |
721 | EXPORT_SYMBOL(sg_copy_to_buffer); |
722 | |
723 | /** |
724 | * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list |
725 | * @sgl: The SG list |
726 | * @nents: Number of SG entries |
727 | * @buf: Where to copy from |
728 | * @buflen: The number of bytes to copy |
729 | * @skip: Number of bytes to skip before copying |
730 | * |
731 | * Returns the number of copied bytes. |
732 | * |
733 | **/ |
734 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
735 | const void *buf, size_t buflen, off_t skip) |
736 | { |
737 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); |
738 | } |
739 | EXPORT_SYMBOL(sg_pcopy_from_buffer); |
740 | |
741 | /** |
742 | * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer |
743 | * @sgl: The SG list |
744 | * @nents: Number of SG entries |
745 | * @buf: Where to copy to |
746 | * @buflen: The number of bytes to copy |
747 | * @skip: Number of bytes to skip before copying |
748 | * |
749 | * Returns the number of copied bytes. |
750 | * |
751 | **/ |
752 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
753 | void *buf, size_t buflen, off_t skip) |
754 | { |
755 | return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); |
756 | } |
757 | EXPORT_SYMBOL(sg_pcopy_to_buffer); |
758 |