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40b0b3f8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0db9299f JA |
2 | /* |
3 | * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> | |
4 | * | |
5 | * Scatterlist handling helpers. | |
0db9299f | 6 | */ |
8bc3bcc9 | 7 | #include <linux/export.h> |
5a0e3ad6 | 8 | #include <linux/slab.h> |
0db9299f | 9 | #include <linux/scatterlist.h> |
b1adaf65 | 10 | #include <linux/highmem.h> |
b94de9bb | 11 | #include <linux/kmemleak.h> |
0db9299f JA |
12 | |
13 | /** | |
14 | * sg_next - return the next scatterlist entry in a list | |
15 | * @sg: The current sg entry | |
16 | * | |
17 | * Description: | |
18 | * Usually the next entry will be @sg@ + 1, but if this sg element is part | |
19 | * of a chained scatterlist, it could jump to the start of a new | |
20 | * scatterlist array. | |
21 | * | |
22 | **/ | |
23 | struct scatterlist *sg_next(struct scatterlist *sg) | |
24 | { | |
0db9299f JA |
25 | if (sg_is_last(sg)) |
26 | return NULL; | |
27 | ||
28 | sg++; | |
29 | if (unlikely(sg_is_chain(sg))) | |
30 | sg = sg_chain_ptr(sg); | |
31 | ||
32 | return sg; | |
33 | } | |
34 | EXPORT_SYMBOL(sg_next); | |
35 | ||
2e484610 ML |
36 | /** |
37 | * sg_nents - return total count of entries in scatterlist | |
38 | * @sg: The scatterlist | |
39 | * | |
40 | * Description: | |
9dbbc3b9 | 41 | * Allows to know how many entries are in sg, taking into account |
2e484610 ML |
42 | * chaining as well |
43 | * | |
44 | **/ | |
45 | int sg_nents(struct scatterlist *sg) | |
46 | { | |
232f1b51 ML |
47 | int nents; |
48 | for (nents = 0; sg; sg = sg_next(sg)) | |
2e484610 | 49 | nents++; |
2e484610 ML |
50 | return nents; |
51 | } | |
52 | EXPORT_SYMBOL(sg_nents); | |
53 | ||
cfaed10d TL |
54 | /** |
55 | * sg_nents_for_len - return total count of entries in scatterlist | |
56 | * needed to satisfy the supplied length | |
57 | * @sg: The scatterlist | |
58 | * @len: The total required length | |
59 | * | |
60 | * Description: | |
61 | * Determines the number of entries in sg that are required to meet | |
9dbbc3b9 | 62 | * the supplied length, taking into account chaining as well |
cfaed10d TL |
63 | * |
64 | * Returns: | |
65 | * the number of sg entries needed, negative error on failure | |
66 | * | |
67 | **/ | |
68 | int sg_nents_for_len(struct scatterlist *sg, u64 len) | |
69 | { | |
70 | int nents; | |
71 | u64 total; | |
72 | ||
73 | if (!len) | |
74 | return 0; | |
75 | ||
76 | for (nents = 0, total = 0; sg; sg = sg_next(sg)) { | |
77 | nents++; | |
78 | total += sg->length; | |
79 | if (total >= len) | |
80 | return nents; | |
81 | } | |
82 | ||
83 | return -EINVAL; | |
84 | } | |
85 | EXPORT_SYMBOL(sg_nents_for_len); | |
2e484610 | 86 | |
0db9299f JA |
87 | /** |
88 | * sg_last - return the last scatterlist entry in a list | |
89 | * @sgl: First entry in the scatterlist | |
90 | * @nents: Number of entries in the scatterlist | |
91 | * | |
92 | * Description: | |
93 | * Should only be used casually, it (currently) scans the entire list | |
94 | * to get the last entry. | |
95 | * | |
96 | * Note that the @sgl@ pointer passed in need not be the first one, | |
97 | * the important bit is that @nents@ denotes the number of entries that | |
98 | * exist from @sgl@. | |
99 | * | |
100 | **/ | |
101 | struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) | |
102 | { | |
0db9299f JA |
103 | struct scatterlist *sg, *ret = NULL; |
104 | unsigned int i; | |
105 | ||
106 | for_each_sg(sgl, sg, nents, i) | |
107 | ret = sg; | |
108 | ||
0db9299f | 109 | BUG_ON(!sg_is_last(ret)); |
0db9299f JA |
110 | return ret; |
111 | } | |
112 | EXPORT_SYMBOL(sg_last); | |
113 | ||
114 | /** | |
115 | * sg_init_table - Initialize SG table | |
116 | * @sgl: The SG table | |
117 | * @nents: Number of entries in table | |
118 | * | |
119 | * Notes: | |
120 | * If this is part of a chained sg table, sg_mark_end() should be | |
121 | * used only on the last table part. | |
122 | * | |
123 | **/ | |
124 | void sg_init_table(struct scatterlist *sgl, unsigned int nents) | |
125 | { | |
126 | memset(sgl, 0, sizeof(*sgl) * nents); | |
f3851786 | 127 | sg_init_marker(sgl, nents); |
0db9299f JA |
128 | } |
129 | EXPORT_SYMBOL(sg_init_table); | |
130 | ||
131 | /** | |
132 | * sg_init_one - Initialize a single entry sg list | |
133 | * @sg: SG entry | |
134 | * @buf: Virtual address for IO | |
135 | * @buflen: IO length | |
136 | * | |
137 | **/ | |
138 | void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) | |
139 | { | |
140 | sg_init_table(sg, 1); | |
141 | sg_set_buf(sg, buf, buflen); | |
142 | } | |
143 | EXPORT_SYMBOL(sg_init_one); | |
144 | ||
145 | /* | |
146 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree | |
147 | * helpers. | |
148 | */ | |
149 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) | |
150 | { | |
b94de9bb CW |
151 | if (nents == SG_MAX_SINGLE_ALLOC) { |
152 | /* | |
153 | * Kmemleak doesn't track page allocations as they are not | |
154 | * commonly used (in a raw form) for kernel data structures. | |
155 | * As we chain together a list of pages and then a normal | |
156 | * kmalloc (tracked by kmemleak), in order to for that last | |
157 | * allocation not to become decoupled (and thus a | |
158 | * false-positive) we need to inform kmemleak of all the | |
159 | * intermediate allocations. | |
160 | */ | |
161 | void *ptr = (void *) __get_free_page(gfp_mask); | |
162 | kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); | |
163 | return ptr; | |
164 | } else | |
6da2ec56 KC |
165 | return kmalloc_array(nents, sizeof(struct scatterlist), |
166 | gfp_mask); | |
0db9299f JA |
167 | } |
168 | ||
169 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) | |
170 | { | |
b94de9bb CW |
171 | if (nents == SG_MAX_SINGLE_ALLOC) { |
172 | kmemleak_free(sg); | |
0db9299f | 173 | free_page((unsigned long) sg); |
b94de9bb | 174 | } else |
0db9299f JA |
175 | kfree(sg); |
176 | } | |
177 | ||
178 | /** | |
179 | * __sg_free_table - Free a previously mapped sg table | |
180 | * @table: The sg table header to use | |
7cedb1f1 | 181 | * @max_ents: The maximum number of entries per single scatterlist |
4635873c ML |
182 | * @nents_first_chunk: Number of entries int the (preallocated) first |
183 | * scatterlist chunk, 0 means no such preallocated first chunk | |
0db9299f | 184 | * @free_fn: Free function |
3e302dbc | 185 | * @num_ents: Number of entries in the table |
0db9299f JA |
186 | * |
187 | * Description: | |
7cedb1f1 JB |
188 | * Free an sg table previously allocated and setup with |
189 | * __sg_alloc_table(). The @max_ents value must be identical to | |
190 | * that previously used with __sg_alloc_table(). | |
0db9299f JA |
191 | * |
192 | **/ | |
7cedb1f1 | 193 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
3e302dbc MG |
194 | unsigned int nents_first_chunk, sg_free_fn *free_fn, |
195 | unsigned int num_ents) | |
0db9299f JA |
196 | { |
197 | struct scatterlist *sgl, *next; | |
4635873c | 198 | unsigned curr_max_ents = nents_first_chunk ?: max_ents; |
0db9299f JA |
199 | |
200 | if (unlikely(!table->sgl)) | |
201 | return; | |
202 | ||
203 | sgl = table->sgl; | |
3e302dbc MG |
204 | while (num_ents) { |
205 | unsigned int alloc_size = num_ents; | |
0db9299f JA |
206 | unsigned int sg_size; |
207 | ||
208 | /* | |
7cedb1f1 | 209 | * If we have more than max_ents segments left, |
0db9299f JA |
210 | * then assign 'next' to the sg table after the current one. |
211 | * sg_size is then one less than alloc size, since the last | |
212 | * element is the chain pointer. | |
213 | */ | |
4635873c ML |
214 | if (alloc_size > curr_max_ents) { |
215 | next = sg_chain_ptr(&sgl[curr_max_ents - 1]); | |
216 | alloc_size = curr_max_ents; | |
0db9299f JA |
217 | sg_size = alloc_size - 1; |
218 | } else { | |
219 | sg_size = alloc_size; | |
220 | next = NULL; | |
221 | } | |
222 | ||
3e302dbc | 223 | num_ents -= sg_size; |
4635873c ML |
224 | if (nents_first_chunk) |
225 | nents_first_chunk = 0; | |
c21e59d8 TB |
226 | else |
227 | free_fn(sgl, alloc_size); | |
0db9299f | 228 | sgl = next; |
4635873c | 229 | curr_max_ents = max_ents; |
0db9299f JA |
230 | } |
231 | ||
232 | table->sgl = NULL; | |
233 | } | |
234 | EXPORT_SYMBOL(__sg_free_table); | |
235 | ||
3e302dbc MG |
236 | /** |
237 | * sg_free_append_table - Free a previously allocated append sg table. | |
238 | * @table: The mapped sg append table header | |
239 | * | |
240 | **/ | |
241 | void sg_free_append_table(struct sg_append_table *table) | |
242 | { | |
6d529ea8 | 243 | __sg_free_table(&table->sgt, SG_MAX_SINGLE_ALLOC, 0, sg_kfree, |
3e302dbc MG |
244 | table->total_nents); |
245 | } | |
246 | EXPORT_SYMBOL(sg_free_append_table); | |
247 | ||
248 | ||
0db9299f JA |
249 | /** |
250 | * sg_free_table - Free a previously allocated sg table | |
251 | * @table: The mapped sg table header | |
252 | * | |
253 | **/ | |
254 | void sg_free_table(struct sg_table *table) | |
255 | { | |
6d529ea8 | 256 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree, |
3e302dbc | 257 | table->orig_nents); |
0db9299f JA |
258 | } |
259 | EXPORT_SYMBOL(sg_free_table); | |
260 | ||
261 | /** | |
262 | * __sg_alloc_table - Allocate and initialize an sg table with given allocator | |
263 | * @table: The sg table header to use | |
264 | * @nents: Number of entries in sg list | |
7cedb1f1 | 265 | * @max_ents: The maximum number of entries the allocator returns per call |
4635873c ML |
266 | * @nents_first_chunk: Number of entries int the (preallocated) first |
267 | * scatterlist chunk, 0 means no such preallocated chunk provided by user | |
0db9299f JA |
268 | * @gfp_mask: GFP allocation mask |
269 | * @alloc_fn: Allocator to use | |
270 | * | |
7cedb1f1 JB |
271 | * Description: |
272 | * This function returns a @table @nents long. The allocator is | |
273 | * defined to return scatterlist chunks of maximum size @max_ents. | |
274 | * Thus if @nents is bigger than @max_ents, the scatterlists will be | |
275 | * chained in units of @max_ents. | |
276 | * | |
0db9299f JA |
277 | * Notes: |
278 | * If this function returns non-0 (eg failure), the caller must call | |
279 | * __sg_free_table() to cleanup any leftover allocations. | |
280 | * | |
281 | **/ | |
7cedb1f1 | 282 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
c53c6d6a | 283 | unsigned int max_ents, struct scatterlist *first_chunk, |
4635873c ML |
284 | unsigned int nents_first_chunk, gfp_t gfp_mask, |
285 | sg_alloc_fn *alloc_fn) | |
0db9299f JA |
286 | { |
287 | struct scatterlist *sg, *prv; | |
288 | unsigned int left; | |
4635873c ML |
289 | unsigned curr_max_ents = nents_first_chunk ?: max_ents; |
290 | unsigned prv_max_ents; | |
0db9299f | 291 | |
27daabd9 DC |
292 | memset(table, 0, sizeof(*table)); |
293 | ||
294 | if (nents == 0) | |
295 | return -EINVAL; | |
7c703e54 | 296 | #ifdef CONFIG_ARCH_NO_SG_CHAIN |
6fd59a83 NB |
297 | if (WARN_ON_ONCE(nents > max_ents)) |
298 | return -EINVAL; | |
0db9299f JA |
299 | #endif |
300 | ||
0db9299f JA |
301 | left = nents; |
302 | prv = NULL; | |
303 | do { | |
304 | unsigned int sg_size, alloc_size = left; | |
305 | ||
4635873c ML |
306 | if (alloc_size > curr_max_ents) { |
307 | alloc_size = curr_max_ents; | |
0db9299f JA |
308 | sg_size = alloc_size - 1; |
309 | } else | |
310 | sg_size = alloc_size; | |
311 | ||
312 | left -= sg_size; | |
313 | ||
c53c6d6a CH |
314 | if (first_chunk) { |
315 | sg = first_chunk; | |
316 | first_chunk = NULL; | |
317 | } else { | |
318 | sg = alloc_fn(alloc_size, gfp_mask); | |
319 | } | |
edce6820 JC |
320 | if (unlikely(!sg)) { |
321 | /* | |
322 | * Adjust entry count to reflect that the last | |
323 | * entry of the previous table won't be used for | |
324 | * linkage. Without this, sg_kfree() may get | |
325 | * confused. | |
326 | */ | |
327 | if (prv) | |
328 | table->nents = ++table->orig_nents; | |
329 | ||
4e456fee | 330 | return -ENOMEM; |
edce6820 | 331 | } |
0db9299f JA |
332 | |
333 | sg_init_table(sg, alloc_size); | |
334 | table->nents = table->orig_nents += sg_size; | |
335 | ||
336 | /* | |
337 | * If this is the first mapping, assign the sg table header. | |
338 | * If this is not the first mapping, chain previous part. | |
339 | */ | |
340 | if (prv) | |
4635873c | 341 | sg_chain(prv, prv_max_ents, sg); |
0db9299f JA |
342 | else |
343 | table->sgl = sg; | |
344 | ||
345 | /* | |
346 | * If no more entries after this one, mark the end | |
347 | */ | |
348 | if (!left) | |
349 | sg_mark_end(&sg[sg_size - 1]); | |
350 | ||
0db9299f | 351 | prv = sg; |
4635873c ML |
352 | prv_max_ents = curr_max_ents; |
353 | curr_max_ents = max_ents; | |
0db9299f JA |
354 | } while (left); |
355 | ||
356 | return 0; | |
357 | } | |
358 | EXPORT_SYMBOL(__sg_alloc_table); | |
359 | ||
360 | /** | |
361 | * sg_alloc_table - Allocate and initialize an sg table | |
362 | * @table: The sg table header to use | |
363 | * @nents: Number of entries in sg list | |
364 | * @gfp_mask: GFP allocation mask | |
365 | * | |
366 | * Description: | |
367 | * Allocate and initialize an sg table. If @nents@ is larger than | |
368 | * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. | |
369 | * | |
370 | **/ | |
371 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) | |
372 | { | |
373 | int ret; | |
374 | ||
7cedb1f1 | 375 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
4635873c | 376 | NULL, 0, gfp_mask, sg_kmalloc); |
0db9299f | 377 | if (unlikely(ret)) |
3e302dbc | 378 | sg_free_table(table); |
0db9299f JA |
379 | return ret; |
380 | } | |
381 | EXPORT_SYMBOL(sg_alloc_table); | |
b1adaf65 | 382 | |
3e302dbc | 383 | static struct scatterlist *get_next_sg(struct sg_append_table *table, |
07da1223 MG |
384 | struct scatterlist *cur, |
385 | unsigned long needed_sges, | |
386 | gfp_t gfp_mask) | |
387 | { | |
388 | struct scatterlist *new_sg, *next_sg; | |
389 | unsigned int alloc_size; | |
390 | ||
391 | if (cur) { | |
392 | next_sg = sg_next(cur); | |
393 | /* Check if last entry should be keeped for chainning */ | |
394 | if (!sg_is_last(next_sg) || needed_sges == 1) | |
395 | return next_sg; | |
396 | } | |
397 | ||
398 | alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC); | |
399 | new_sg = sg_kmalloc(alloc_size, gfp_mask); | |
400 | if (!new_sg) | |
401 | return ERR_PTR(-ENOMEM); | |
402 | sg_init_table(new_sg, alloc_size); | |
403 | if (cur) { | |
3e302dbc | 404 | table->total_nents += alloc_size - 1; |
07da1223 | 405 | __sg_chain(next_sg, new_sg); |
07da1223 | 406 | } else { |
3e302dbc MG |
407 | table->sgt.sgl = new_sg; |
408 | table->total_nents = alloc_size; | |
07da1223 MG |
409 | } |
410 | return new_sg; | |
411 | } | |
412 | ||
efc42bc9 | 413 | /** |
3e302dbc MG |
414 | * sg_alloc_append_table_from_pages - Allocate and initialize an append sg |
415 | * table from an array of pages | |
416 | * @sgt_append: The sg append table to use | |
417 | * @pages: Pointer to an array of page pointers | |
418 | * @n_pages: Number of pages in the pages array | |
89d8589c TU |
419 | * @offset: Offset from start of the first page to the start of a buffer |
420 | * @size: Number of valid bytes in the buffer (after offset) | |
9a40401c | 421 | * @max_segment: Maximum size of a scatterlist element in bytes |
07da1223 | 422 | * @left_pages: Left pages caller have to set after this call |
89d8589c | 423 | * @gfp_mask: GFP allocation mask |
efc42bc9 | 424 | * |
07da1223 | 425 | * Description: |
3e302dbc MG |
426 | * In the first call it allocate and initialize an sg table from a list of |
427 | * pages, else reuse the scatterlist from sgt_append. Contiguous ranges of | |
428 | * the pages are squashed into a single scatterlist entry up to the maximum | |
429 | * size specified in @max_segment. A user may provide an offset at a start | |
430 | * and a size of valid data in a buffer specified by the page array. The | |
431 | * returned sg table is released by sg_free_append_table | |
efc42bc9 TS |
432 | * |
433 | * Returns: | |
3e302dbc | 434 | * 0 on success, negative error on failure |
07da1223 MG |
435 | * |
436 | * Notes: | |
437 | * If this function returns non-0 (eg failure), the caller must call | |
3e302dbc MG |
438 | * sg_free_append_table() to cleanup any leftover allocations. |
439 | * | |
440 | * In the fist call, sgt_append must by initialized. | |
efc42bc9 | 441 | */ |
3e302dbc | 442 | int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append, |
07da1223 MG |
443 | struct page **pages, unsigned int n_pages, unsigned int offset, |
444 | unsigned long size, unsigned int max_segment, | |
3e302dbc | 445 | unsigned int left_pages, gfp_t gfp_mask) |
efc42bc9 | 446 | { |
07da1223 MG |
447 | unsigned int chunks, cur_page, seg_len, i, prv_len = 0; |
448 | unsigned int added_nents = 0; | |
3e302dbc | 449 | struct scatterlist *s = sgt_append->prv; |
efc42bc9 | 450 | |
9a40401c JG |
451 | /* |
452 | * The algorithm below requires max_segment to be aligned to PAGE_SIZE | |
453 | * otherwise it can overshoot. | |
454 | */ | |
455 | max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE); | |
456 | if (WARN_ON(max_segment < PAGE_SIZE)) | |
3e302dbc | 457 | return -EINVAL; |
07da1223 | 458 | |
3e302dbc MG |
459 | if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && sgt_append->prv) |
460 | return -EOPNOTSUPP; | |
07da1223 | 461 | |
3e302dbc MG |
462 | if (sgt_append->prv) { |
463 | unsigned long paddr = | |
464 | (page_to_pfn(sg_page(sgt_append->prv)) * PAGE_SIZE + | |
465 | sgt_append->prv->offset + sgt_append->prv->length) / | |
466 | PAGE_SIZE; | |
07da1223 MG |
467 | |
468 | if (WARN_ON(offset)) | |
3e302dbc | 469 | return -EINVAL; |
07da1223 MG |
470 | |
471 | /* Merge contiguous pages into the last SG */ | |
3e302dbc | 472 | prv_len = sgt_append->prv->length; |
07da1223 | 473 | while (n_pages && page_to_pfn(pages[0]) == paddr) { |
3e302dbc | 474 | if (sgt_append->prv->length + PAGE_SIZE > max_segment) |
07da1223 | 475 | break; |
3e302dbc | 476 | sgt_append->prv->length += PAGE_SIZE; |
07da1223 MG |
477 | paddr++; |
478 | pages++; | |
479 | n_pages--; | |
480 | } | |
481 | if (!n_pages) | |
482 | goto out; | |
483 | } | |
89d8589c | 484 | |
efc42bc9 TS |
485 | /* compute number of contiguous chunks */ |
486 | chunks = 1; | |
c125906b TU |
487 | seg_len = 0; |
488 | for (i = 1; i < n_pages; i++) { | |
489 | seg_len += PAGE_SIZE; | |
490 | if (seg_len >= max_segment || | |
491 | page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) { | |
492 | chunks++; | |
493 | seg_len = 0; | |
494 | } | |
495 | } | |
efc42bc9 | 496 | |
efc42bc9 TS |
497 | /* merging chunks and putting them into the scatterlist */ |
498 | cur_page = 0; | |
07da1223 | 499 | for (i = 0; i < chunks; i++) { |
c125906b | 500 | unsigned int j, chunk_size; |
efc42bc9 TS |
501 | |
502 | /* look for the end of the current chunk */ | |
c125906b TU |
503 | seg_len = 0; |
504 | for (j = cur_page + 1; j < n_pages; j++) { | |
505 | seg_len += PAGE_SIZE; | |
506 | if (seg_len >= max_segment || | |
507 | page_to_pfn(pages[j]) != | |
efc42bc9 TS |
508 | page_to_pfn(pages[j - 1]) + 1) |
509 | break; | |
c125906b | 510 | } |
efc42bc9 | 511 | |
07da1223 | 512 | /* Pass how many chunks might be left */ |
3e302dbc MG |
513 | s = get_next_sg(sgt_append, s, chunks - i + left_pages, |
514 | gfp_mask); | |
07da1223 MG |
515 | if (IS_ERR(s)) { |
516 | /* | |
517 | * Adjust entry length to be as before function was | |
518 | * called. | |
519 | */ | |
3e302dbc MG |
520 | if (sgt_append->prv) |
521 | sgt_append->prv->length = prv_len; | |
522 | return PTR_ERR(s); | |
07da1223 | 523 | } |
efc42bc9 | 524 | chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; |
c125906b TU |
525 | sg_set_page(s, pages[cur_page], |
526 | min_t(unsigned long, size, chunk_size), offset); | |
07da1223 | 527 | added_nents++; |
efc42bc9 TS |
528 | size -= chunk_size; |
529 | offset = 0; | |
530 | cur_page = j; | |
531 | } | |
3e302dbc MG |
532 | sgt_append->sgt.nents += added_nents; |
533 | sgt_append->sgt.orig_nents = sgt_append->sgt.nents; | |
534 | sgt_append->prv = s; | |
07da1223 MG |
535 | out: |
536 | if (!left_pages) | |
537 | sg_mark_end(s); | |
3e302dbc | 538 | return 0; |
efc42bc9 | 539 | } |
90e7a6de | 540 | EXPORT_SYMBOL(sg_alloc_append_table_from_pages); |
89d8589c TU |
541 | |
542 | /** | |
90e7a6de MG |
543 | * sg_alloc_table_from_pages_segment - Allocate and initialize an sg table from |
544 | * an array of pages and given maximum | |
545 | * segment. | |
89d8589c TU |
546 | * @sgt: The sg table header to use |
547 | * @pages: Pointer to an array of page pointers | |
548 | * @n_pages: Number of pages in the pages array | |
549 | * @offset: Offset from start of the first page to the start of a buffer | |
550 | * @size: Number of valid bytes in the buffer (after offset) | |
90e7a6de | 551 | * @max_segment: Maximum size of a scatterlist element in bytes |
89d8589c TU |
552 | * @gfp_mask: GFP allocation mask |
553 | * | |
554 | * Description: | |
555 | * Allocate and initialize an sg table from a list of pages. Contiguous | |
90e7a6de MG |
556 | * ranges of the pages are squashed into a single scatterlist node up to the |
557 | * maximum size specified in @max_segment. A user may provide an offset at a | |
558 | * start and a size of valid data in a buffer specified by the page array. | |
89d8589c | 559 | * |
90e7a6de MG |
560 | * The returned sg table is released by sg_free_table. |
561 | * | |
562 | * Returns: | |
89d8589c TU |
563 | * 0 on success, negative error on failure |
564 | */ | |
90e7a6de MG |
565 | int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages, |
566 | unsigned int n_pages, unsigned int offset, | |
567 | unsigned long size, unsigned int max_segment, | |
568 | gfp_t gfp_mask) | |
89d8589c | 569 | { |
3e302dbc MG |
570 | struct sg_append_table append = {}; |
571 | int err; | |
572 | ||
573 | err = sg_alloc_append_table_from_pages(&append, pages, n_pages, offset, | |
574 | size, max_segment, 0, gfp_mask); | |
575 | if (err) { | |
576 | sg_free_append_table(&append); | |
577 | return err; | |
578 | } | |
579 | memcpy(sgt, &append.sgt, sizeof(*sgt)); | |
580 | WARN_ON(append.total_nents != sgt->orig_nents); | |
581 | return 0; | |
89d8589c | 582 | } |
90e7a6de | 583 | EXPORT_SYMBOL(sg_alloc_table_from_pages_segment); |
efc42bc9 | 584 | |
e80a0af4 BVA |
585 | #ifdef CONFIG_SGL_ALLOC |
586 | ||
587 | /** | |
588 | * sgl_alloc_order - allocate a scatterlist and its pages | |
589 | * @length: Length in bytes of the scatterlist. Must be at least one | |
590 | * @order: Second argument for alloc_pages() | |
591 | * @chainable: Whether or not to allocate an extra element in the scatterlist | |
592 | * for scatterlist chaining purposes | |
593 | * @gfp: Memory allocation flags | |
594 | * @nent_p: [out] Number of entries in the scatterlist that have pages | |
595 | * | |
596 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
597 | */ | |
598 | struct scatterlist *sgl_alloc_order(unsigned long long length, | |
599 | unsigned int order, bool chainable, | |
600 | gfp_t gfp, unsigned int *nent_p) | |
601 | { | |
602 | struct scatterlist *sgl, *sg; | |
603 | struct page *page; | |
604 | unsigned int nent, nalloc; | |
605 | u32 elem_len; | |
606 | ||
607 | nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); | |
608 | /* Check for integer overflow */ | |
609 | if (length > (nent << (PAGE_SHIFT + order))) | |
610 | return NULL; | |
611 | nalloc = nent; | |
612 | if (chainable) { | |
613 | /* Check for integer overflow */ | |
614 | if (nalloc + 1 < nalloc) | |
615 | return NULL; | |
616 | nalloc++; | |
617 | } | |
618 | sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), | |
6ed9b92e | 619 | gfp & ~GFP_DMA); |
e80a0af4 BVA |
620 | if (!sgl) |
621 | return NULL; | |
622 | ||
8c7a8d1c | 623 | sg_init_table(sgl, nalloc); |
e80a0af4 BVA |
624 | sg = sgl; |
625 | while (length) { | |
626 | elem_len = min_t(u64, length, PAGE_SIZE << order); | |
627 | page = alloc_pages(gfp, order); | |
628 | if (!page) { | |
b2a182a4 | 629 | sgl_free_order(sgl, order); |
e80a0af4 BVA |
630 | return NULL; |
631 | } | |
632 | ||
633 | sg_set_page(sg, page, elem_len, 0); | |
634 | length -= elem_len; | |
635 | sg = sg_next(sg); | |
636 | } | |
8c7a8d1c | 637 | WARN_ONCE(length, "length = %lld\n", length); |
e80a0af4 BVA |
638 | if (nent_p) |
639 | *nent_p = nent; | |
640 | return sgl; | |
641 | } | |
642 | EXPORT_SYMBOL(sgl_alloc_order); | |
643 | ||
644 | /** | |
645 | * sgl_alloc - allocate a scatterlist and its pages | |
646 | * @length: Length in bytes of the scatterlist | |
647 | * @gfp: Memory allocation flags | |
648 | * @nent_p: [out] Number of entries in the scatterlist | |
649 | * | |
650 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
651 | */ | |
652 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, | |
653 | unsigned int *nent_p) | |
654 | { | |
655 | return sgl_alloc_order(length, 0, false, gfp, nent_p); | |
656 | } | |
657 | EXPORT_SYMBOL(sgl_alloc); | |
658 | ||
659 | /** | |
8c7a8d1c | 660 | * sgl_free_n_order - free a scatterlist and its pages |
e80a0af4 | 661 | * @sgl: Scatterlist with one or more elements |
8c7a8d1c | 662 | * @nents: Maximum number of elements to free |
e80a0af4 | 663 | * @order: Second argument for __free_pages() |
8c7a8d1c BVA |
664 | * |
665 | * Notes: | |
666 | * - If several scatterlists have been chained and each chain element is | |
667 | * freed separately then it's essential to set nents correctly to avoid that a | |
668 | * page would get freed twice. | |
669 | * - All pages in a chained scatterlist can be freed at once by setting @nents | |
670 | * to a high number. | |
e80a0af4 | 671 | */ |
8c7a8d1c | 672 | void sgl_free_n_order(struct scatterlist *sgl, int nents, int order) |
e80a0af4 BVA |
673 | { |
674 | struct scatterlist *sg; | |
675 | struct page *page; | |
8c7a8d1c | 676 | int i; |
e80a0af4 | 677 | |
8c7a8d1c BVA |
678 | for_each_sg(sgl, sg, nents, i) { |
679 | if (!sg) | |
680 | break; | |
e80a0af4 BVA |
681 | page = sg_page(sg); |
682 | if (page) | |
683 | __free_pages(page, order); | |
684 | } | |
685 | kfree(sgl); | |
686 | } | |
8c7a8d1c BVA |
687 | EXPORT_SYMBOL(sgl_free_n_order); |
688 | ||
689 | /** | |
690 | * sgl_free_order - free a scatterlist and its pages | |
691 | * @sgl: Scatterlist with one or more elements | |
692 | * @order: Second argument for __free_pages() | |
693 | */ | |
694 | void sgl_free_order(struct scatterlist *sgl, int order) | |
695 | { | |
696 | sgl_free_n_order(sgl, INT_MAX, order); | |
697 | } | |
e80a0af4 BVA |
698 | EXPORT_SYMBOL(sgl_free_order); |
699 | ||
700 | /** | |
701 | * sgl_free - free a scatterlist and its pages | |
702 | * @sgl: Scatterlist with one or more elements | |
703 | */ | |
704 | void sgl_free(struct scatterlist *sgl) | |
705 | { | |
706 | sgl_free_order(sgl, 0); | |
707 | } | |
708 | EXPORT_SYMBOL(sgl_free); | |
709 | ||
710 | #endif /* CONFIG_SGL_ALLOC */ | |
711 | ||
a321e91b ID |
712 | void __sg_page_iter_start(struct sg_page_iter *piter, |
713 | struct scatterlist *sglist, unsigned int nents, | |
714 | unsigned long pgoffset) | |
715 | { | |
716 | piter->__pg_advance = 0; | |
717 | piter->__nents = nents; | |
718 | ||
a321e91b ID |
719 | piter->sg = sglist; |
720 | piter->sg_pgoffset = pgoffset; | |
721 | } | |
722 | EXPORT_SYMBOL(__sg_page_iter_start); | |
723 | ||
724 | static int sg_page_count(struct scatterlist *sg) | |
725 | { | |
726 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; | |
727 | } | |
728 | ||
729 | bool __sg_page_iter_next(struct sg_page_iter *piter) | |
730 | { | |
731 | if (!piter->__nents || !piter->sg) | |
732 | return false; | |
733 | ||
734 | piter->sg_pgoffset += piter->__pg_advance; | |
735 | piter->__pg_advance = 1; | |
736 | ||
737 | while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { | |
738 | piter->sg_pgoffset -= sg_page_count(piter->sg); | |
739 | piter->sg = sg_next(piter->sg); | |
740 | if (!--piter->__nents || !piter->sg) | |
741 | return false; | |
742 | } | |
a321e91b ID |
743 | |
744 | return true; | |
745 | } | |
746 | EXPORT_SYMBOL(__sg_page_iter_next); | |
747 | ||
d901b276 JG |
748 | static int sg_dma_page_count(struct scatterlist *sg) |
749 | { | |
750 | return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT; | |
751 | } | |
752 | ||
753 | bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter) | |
754 | { | |
755 | struct sg_page_iter *piter = &dma_iter->base; | |
756 | ||
757 | if (!piter->__nents || !piter->sg) | |
758 | return false; | |
759 | ||
760 | piter->sg_pgoffset += piter->__pg_advance; | |
761 | piter->__pg_advance = 1; | |
762 | ||
763 | while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) { | |
764 | piter->sg_pgoffset -= sg_dma_page_count(piter->sg); | |
765 | piter->sg = sg_next(piter->sg); | |
766 | if (!--piter->__nents || !piter->sg) | |
767 | return false; | |
768 | } | |
769 | ||
770 | return true; | |
771 | } | |
772 | EXPORT_SYMBOL(__sg_page_iter_dma_next); | |
773 | ||
137d3edb TH |
774 | /** |
775 | * sg_miter_start - start mapping iteration over a sg list | |
776 | * @miter: sg mapping iter to be started | |
777 | * @sgl: sg list to iterate over | |
778 | * @nents: number of sg entries | |
779 | * | |
780 | * Description: | |
781 | * Starts mapping iterator @miter. | |
782 | * | |
783 | * Context: | |
784 | * Don't care. | |
785 | */ | |
786 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
787 | unsigned int nents, unsigned int flags) | |
788 | { | |
789 | memset(miter, 0, sizeof(struct sg_mapping_iter)); | |
790 | ||
4225fc85 | 791 | __sg_page_iter_start(&miter->piter, sgl, nents, 0); |
6de7e356 | 792 | WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); |
137d3edb TH |
793 | miter->__flags = flags; |
794 | } | |
795 | EXPORT_SYMBOL(sg_miter_start); | |
796 | ||
11052004 AM |
797 | static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) |
798 | { | |
799 | if (!miter->__remaining) { | |
800 | struct scatterlist *sg; | |
11052004 AM |
801 | |
802 | if (!__sg_page_iter_next(&miter->piter)) | |
803 | return false; | |
804 | ||
805 | sg = miter->piter.sg; | |
11052004 | 806 | |
aeb87246 CL |
807 | miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset; |
808 | miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT; | |
809 | miter->__offset &= PAGE_SIZE - 1; | |
11052004 | 810 | miter->__remaining = sg->offset + sg->length - |
aeb87246 CL |
811 | (miter->piter.sg_pgoffset << PAGE_SHIFT) - |
812 | miter->__offset; | |
11052004 AM |
813 | miter->__remaining = min_t(unsigned long, miter->__remaining, |
814 | PAGE_SIZE - miter->__offset); | |
815 | } | |
816 | ||
817 | return true; | |
818 | } | |
819 | ||
df642cea AM |
820 | /** |
821 | * sg_miter_skip - reposition mapping iterator | |
822 | * @miter: sg mapping iter to be skipped | |
823 | * @offset: number of bytes to plus the current location | |
824 | * | |
825 | * Description: | |
826 | * Sets the offset of @miter to its current location plus @offset bytes. | |
827 | * If mapping iterator @miter has been proceeded by sg_miter_next(), this | |
828 | * stops @miter. | |
829 | * | |
830 | * Context: | |
723aca20 | 831 | * Don't care. |
df642cea AM |
832 | * |
833 | * Returns: | |
834 | * true if @miter contains the valid mapping. false if end of sg | |
835 | * list is reached. | |
836 | */ | |
0d6077f8 | 837 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) |
df642cea AM |
838 | { |
839 | sg_miter_stop(miter); | |
840 | ||
841 | while (offset) { | |
842 | off_t consumed; | |
843 | ||
844 | if (!sg_miter_get_next_page(miter)) | |
845 | return false; | |
846 | ||
847 | consumed = min_t(off_t, offset, miter->__remaining); | |
848 | miter->__offset += consumed; | |
849 | miter->__remaining -= consumed; | |
850 | offset -= consumed; | |
851 | } | |
852 | ||
853 | return true; | |
854 | } | |
0d6077f8 | 855 | EXPORT_SYMBOL(sg_miter_skip); |
df642cea | 856 | |
137d3edb TH |
857 | /** |
858 | * sg_miter_next - proceed mapping iterator to the next mapping | |
859 | * @miter: sg mapping iter to proceed | |
860 | * | |
861 | * Description: | |
8290e2d2 TH |
862 | * Proceeds @miter to the next mapping. @miter should have been started |
863 | * using sg_miter_start(). On successful return, @miter->page, | |
864 | * @miter->addr and @miter->length point to the current mapping. | |
137d3edb TH |
865 | * |
866 | * Context: | |
723aca20 | 867 | * May sleep if !SG_MITER_ATOMIC. |
137d3edb TH |
868 | * |
869 | * Returns: | |
870 | * true if @miter contains the next mapping. false if end of sg | |
871 | * list is reached. | |
872 | */ | |
873 | bool sg_miter_next(struct sg_mapping_iter *miter) | |
874 | { | |
137d3edb TH |
875 | sg_miter_stop(miter); |
876 | ||
4225fc85 ID |
877 | /* |
878 | * Get to the next page if necessary. | |
879 | * __remaining, __offset is adjusted by sg_miter_stop | |
880 | */ | |
11052004 AM |
881 | if (!sg_miter_get_next_page(miter)) |
882 | return false; | |
137d3edb | 883 | |
2db76d7c | 884 | miter->page = sg_page_iter_page(&miter->piter); |
4225fc85 | 885 | miter->consumed = miter->length = miter->__remaining; |
137d3edb TH |
886 | |
887 | if (miter->__flags & SG_MITER_ATOMIC) | |
4225fc85 | 888 | miter->addr = kmap_atomic(miter->page) + miter->__offset; |
137d3edb | 889 | else |
4225fc85 | 890 | miter->addr = kmap(miter->page) + miter->__offset; |
137d3edb TH |
891 | |
892 | return true; | |
893 | } | |
894 | EXPORT_SYMBOL(sg_miter_next); | |
895 | ||
896 | /** | |
897 | * sg_miter_stop - stop mapping iteration | |
898 | * @miter: sg mapping iter to be stopped | |
899 | * | |
900 | * Description: | |
901 | * Stops mapping iterator @miter. @miter should have been started | |
4ba6a2b2 MY |
902 | * using sg_miter_start(). A stopped iteration can be resumed by |
903 | * calling sg_miter_next() on it. This is useful when resources (kmap) | |
904 | * need to be released during iteration. | |
137d3edb TH |
905 | * |
906 | * Context: | |
723aca20 | 907 | * Don't care otherwise. |
137d3edb TH |
908 | */ |
909 | void sg_miter_stop(struct sg_mapping_iter *miter) | |
910 | { | |
911 | WARN_ON(miter->consumed > miter->length); | |
912 | ||
913 | /* drop resources from the last iteration */ | |
914 | if (miter->addr) { | |
915 | miter->__offset += miter->consumed; | |
4225fc85 | 916 | miter->__remaining -= miter->consumed; |
137d3edb | 917 | |
0e84f5db CH |
918 | if (miter->__flags & SG_MITER_TO_SG) |
919 | flush_dcache_page(miter->page); | |
6de7e356 | 920 | |
137d3edb | 921 | if (miter->__flags & SG_MITER_ATOMIC) { |
723aca20 | 922 | WARN_ON_ONCE(!pagefault_disabled()); |
c3eede8e | 923 | kunmap_atomic(miter->addr); |
137d3edb | 924 | } else |
f652c521 | 925 | kunmap(miter->page); |
137d3edb TH |
926 | |
927 | miter->page = NULL; | |
928 | miter->addr = NULL; | |
929 | miter->length = 0; | |
930 | miter->consumed = 0; | |
931 | } | |
932 | } | |
933 | EXPORT_SYMBOL(sg_miter_stop); | |
934 | ||
b1adaf65 FT |
935 | /** |
936 | * sg_copy_buffer - Copy data between a linear buffer and an SG list | |
937 | * @sgl: The SG list | |
938 | * @nents: Number of SG entries | |
939 | * @buf: Where to copy from | |
940 | * @buflen: The number of bytes to copy | |
df642cea AM |
941 | * @skip: Number of bytes to skip before copying |
942 | * @to_buffer: transfer direction (true == from an sg list to a | |
6e853185 | 943 | * buffer, false == from a buffer to an sg list) |
b1adaf65 FT |
944 | * |
945 | * Returns the number of copied bytes. | |
946 | * | |
947 | **/ | |
386ecb12 DG |
948 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
949 | size_t buflen, off_t skip, bool to_buffer) | |
b1adaf65 | 950 | { |
137d3edb TH |
951 | unsigned int offset = 0; |
952 | struct sg_mapping_iter miter; | |
6de7e356 SAS |
953 | unsigned int sg_flags = SG_MITER_ATOMIC; |
954 | ||
955 | if (to_buffer) | |
956 | sg_flags |= SG_MITER_FROM_SG; | |
957 | else | |
958 | sg_flags |= SG_MITER_TO_SG; | |
137d3edb | 959 | |
6de7e356 | 960 | sg_miter_start(&miter, sgl, nents, sg_flags); |
137d3edb | 961 | |
df642cea | 962 | if (!sg_miter_skip(&miter, skip)) |
1f41be7d | 963 | return 0; |
df642cea | 964 | |
1d5210ef | 965 | while ((offset < buflen) && sg_miter_next(&miter)) { |
137d3edb TH |
966 | unsigned int len; |
967 | ||
968 | len = min(miter.length, buflen - offset); | |
969 | ||
970 | if (to_buffer) | |
971 | memcpy(buf + offset, miter.addr, len); | |
6de7e356 | 972 | else |
137d3edb | 973 | memcpy(miter.addr, buf + offset, len); |
b1adaf65 | 974 | |
137d3edb | 975 | offset += len; |
b1adaf65 FT |
976 | } |
977 | ||
137d3edb TH |
978 | sg_miter_stop(&miter); |
979 | ||
980 | return offset; | |
b1adaf65 | 981 | } |
386ecb12 | 982 | EXPORT_SYMBOL(sg_copy_buffer); |
b1adaf65 FT |
983 | |
984 | /** | |
985 | * sg_copy_from_buffer - Copy from a linear buffer to an SG list | |
986 | * @sgl: The SG list | |
987 | * @nents: Number of SG entries | |
988 | * @buf: Where to copy from | |
989 | * @buflen: The number of bytes to copy | |
990 | * | |
991 | * Returns the number of copied bytes. | |
992 | * | |
993 | **/ | |
994 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 995 | const void *buf, size_t buflen) |
b1adaf65 | 996 | { |
2a1bf8f9 | 997 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); |
b1adaf65 FT |
998 | } |
999 | EXPORT_SYMBOL(sg_copy_from_buffer); | |
1000 | ||
1001 | /** | |
1002 | * sg_copy_to_buffer - Copy from an SG list to a linear buffer | |
1003 | * @sgl: The SG list | |
1004 | * @nents: Number of SG entries | |
1005 | * @buf: Where to copy to | |
1006 | * @buflen: The number of bytes to copy | |
1007 | * | |
1008 | * Returns the number of copied bytes. | |
1009 | * | |
1010 | **/ | |
1011 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
1012 | void *buf, size_t buflen) | |
1013 | { | |
df642cea | 1014 | return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); |
b1adaf65 FT |
1015 | } |
1016 | EXPORT_SYMBOL(sg_copy_to_buffer); | |
df642cea AM |
1017 | |
1018 | /** | |
1019 | * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list | |
1020 | * @sgl: The SG list | |
1021 | * @nents: Number of SG entries | |
1022 | * @buf: Where to copy from | |
df642cea | 1023 | * @buflen: The number of bytes to copy |
4dc7daf8 | 1024 | * @skip: Number of bytes to skip before copying |
df642cea AM |
1025 | * |
1026 | * Returns the number of copied bytes. | |
1027 | * | |
1028 | **/ | |
1029 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 1030 | const void *buf, size_t buflen, off_t skip) |
df642cea | 1031 | { |
2a1bf8f9 | 1032 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); |
df642cea AM |
1033 | } |
1034 | EXPORT_SYMBOL(sg_pcopy_from_buffer); | |
1035 | ||
1036 | /** | |
1037 | * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer | |
1038 | * @sgl: The SG list | |
1039 | * @nents: Number of SG entries | |
1040 | * @buf: Where to copy to | |
df642cea | 1041 | * @buflen: The number of bytes to copy |
4dc7daf8 | 1042 | * @skip: Number of bytes to skip before copying |
df642cea AM |
1043 | * |
1044 | * Returns the number of copied bytes. | |
1045 | * | |
1046 | **/ | |
1047 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
1048 | void *buf, size_t buflen, off_t skip) | |
1049 | { | |
1050 | return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); | |
1051 | } | |
1052 | EXPORT_SYMBOL(sg_pcopy_to_buffer); | |
0945e569 JT |
1053 | |
1054 | /** | |
1055 | * sg_zero_buffer - Zero-out a part of a SG list | |
1056 | * @sgl: The SG list | |
1057 | * @nents: Number of SG entries | |
1058 | * @buflen: The number of bytes to zero out | |
1059 | * @skip: Number of bytes to skip before zeroing | |
1060 | * | |
1061 | * Returns the number of bytes zeroed. | |
1062 | **/ | |
1063 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, | |
1064 | size_t buflen, off_t skip) | |
1065 | { | |
1066 | unsigned int offset = 0; | |
1067 | struct sg_mapping_iter miter; | |
1068 | unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; | |
1069 | ||
1070 | sg_miter_start(&miter, sgl, nents, sg_flags); | |
1071 | ||
1072 | if (!sg_miter_skip(&miter, skip)) | |
1073 | return false; | |
1074 | ||
1075 | while (offset < buflen && sg_miter_next(&miter)) { | |
1076 | unsigned int len; | |
1077 | ||
1078 | len = min(miter.length, buflen - offset); | |
1079 | memset(miter.addr, 0, len); | |
1080 | ||
1081 | offset += len; | |
1082 | } | |
1083 | ||
1084 | sg_miter_stop(&miter); | |
1085 | return offset; | |
1086 | } | |
1087 | EXPORT_SYMBOL(sg_zero_buffer); |