Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
4 : *
5 : * Scatterlist handling helpers.
6 : */
7 : #include <linux/export.h>
8 : #include <linux/slab.h>
9 : #include <linux/scatterlist.h>
10 : #include <linux/highmem.h>
11 : #include <linux/kmemleak.h>
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 47566 : struct scatterlist *sg_next(struct scatterlist *sg)
24 : {
25 47566 : if (sg_is_last(sg))
26 : return NULL;
27 :
28 24007 : sg++;
29 24007 : if (unlikely(sg_is_chain(sg)))
30 0 : sg = sg_chain_ptr(sg);
31 :
32 : return sg;
33 : }
34 : EXPORT_SYMBOL(sg_next);
35 :
36 : /**
37 : * sg_nents - return total count of entries in scatterlist
38 : * @sg: The scatterlist
39 : *
40 : * Description:
41 : * Allows to know how many entries are in sg, taking into acount
42 : * chaining as well
43 : *
44 : **/
45 0 : int sg_nents(struct scatterlist *sg)
46 : {
47 0 : int nents;
48 0 : for (nents = 0; sg; sg = sg_next(sg))
49 0 : nents++;
50 0 : return nents;
51 : }
52 : EXPORT_SYMBOL(sg_nents);
53 :
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
62 : * the supplied length, taking into acount chaining as well
63 : *
64 : * Returns:
65 : * the number of sg entries needed, negative error on failure
66 : *
67 : **/
68 0 : int sg_nents_for_len(struct scatterlist *sg, u64 len)
69 : {
70 0 : int nents;
71 0 : u64 total;
72 :
73 0 : if (!len)
74 : return 0;
75 :
76 0 : for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
77 0 : nents++;
78 0 : total += sg->length;
79 0 : if (total >= len)
80 0 : return nents;
81 : }
82 :
83 : return -EINVAL;
84 : }
85 : EXPORT_SYMBOL(sg_nents_for_len);
86 :
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 0 : struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
102 : {
103 0 : struct scatterlist *sg, *ret = NULL;
104 0 : unsigned int i;
105 :
106 0 : for_each_sg(sgl, sg, nents, i)
107 0 : ret = sg;
108 :
109 0 : BUG_ON(!sg_is_last(ret));
110 0 : 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 10466 : void sg_init_table(struct scatterlist *sgl, unsigned int nents)
125 : {
126 10466 : memset(sgl, 0, sizeof(*sgl) * nents);
127 10466 : sg_init_marker(sgl, nents);
128 10466 : }
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 8986 : void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
139 : {
140 8986 : sg_init_table(sg, 1);
141 8986 : sg_set_buf(sg, buf, buflen);
142 8986 : }
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 0 : static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
150 : {
151 0 : 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 0 : void *ptr = (void *) __get_free_page(gfp_mask);
162 0 : kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
163 0 : return ptr;
164 : } else
165 0 : return kmalloc_array(nents, sizeof(struct scatterlist),
166 : gfp_mask);
167 : }
168 :
169 0 : static void sg_kfree(struct scatterlist *sg, unsigned int nents)
170 : {
171 0 : if (nents == SG_MAX_SINGLE_ALLOC) {
172 0 : kmemleak_free(sg);
173 0 : free_page((unsigned long) sg);
174 : } else
175 0 : kfree(sg);
176 0 : }
177 :
178 : /**
179 : * __sg_free_table - Free a previously mapped sg table
180 : * @table: The sg table header to use
181 : * @max_ents: The maximum number of entries per single scatterlist
182 : * @nents_first_chunk: Number of entries int the (preallocated) first
183 : * scatterlist chunk, 0 means no such preallocated first chunk
184 : * @free_fn: Free function
185 : *
186 : * Description:
187 : * Free an sg table previously allocated and setup with
188 : * __sg_alloc_table(). The @max_ents value must be identical to
189 : * that previously used with __sg_alloc_table().
190 : *
191 : **/
192 0 : void __sg_free_table(struct sg_table *table, unsigned int max_ents,
193 : unsigned int nents_first_chunk, sg_free_fn *free_fn)
194 : {
195 0 : struct scatterlist *sgl, *next;
196 0 : unsigned curr_max_ents = nents_first_chunk ?: max_ents;
197 :
198 0 : if (unlikely(!table->sgl))
199 : return;
200 :
201 : sgl = table->sgl;
202 0 : while (table->orig_nents) {
203 0 : unsigned int alloc_size = table->orig_nents;
204 0 : unsigned int sg_size;
205 :
206 : /*
207 : * If we have more than max_ents segments left,
208 : * then assign 'next' to the sg table after the current one.
209 : * sg_size is then one less than alloc size, since the last
210 : * element is the chain pointer.
211 : */
212 0 : if (alloc_size > curr_max_ents) {
213 0 : next = sg_chain_ptr(&sgl[curr_max_ents - 1]);
214 0 : alloc_size = curr_max_ents;
215 0 : sg_size = alloc_size - 1;
216 : } else {
217 : sg_size = alloc_size;
218 : next = NULL;
219 : }
220 :
221 0 : table->orig_nents -= sg_size;
222 0 : if (nents_first_chunk)
223 : nents_first_chunk = 0;
224 : else
225 0 : free_fn(sgl, alloc_size);
226 : sgl = next;
227 : curr_max_ents = max_ents;
228 : }
229 :
230 0 : table->sgl = NULL;
231 : }
232 : EXPORT_SYMBOL(__sg_free_table);
233 :
234 : /**
235 : * sg_free_table - Free a previously allocated sg table
236 : * @table: The mapped sg table header
237 : *
238 : **/
239 0 : void sg_free_table(struct sg_table *table)
240 : {
241 0 : __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
242 0 : }
243 : EXPORT_SYMBOL(sg_free_table);
244 :
245 : /**
246 : * __sg_alloc_table - Allocate and initialize an sg table with given allocator
247 : * @table: The sg table header to use
248 : * @nents: Number of entries in sg list
249 : * @max_ents: The maximum number of entries the allocator returns per call
250 : * @nents_first_chunk: Number of entries int the (preallocated) first
251 : * scatterlist chunk, 0 means no such preallocated chunk provided by user
252 : * @gfp_mask: GFP allocation mask
253 : * @alloc_fn: Allocator to use
254 : *
255 : * Description:
256 : * This function returns a @table @nents long. The allocator is
257 : * defined to return scatterlist chunks of maximum size @max_ents.
258 : * Thus if @nents is bigger than @max_ents, the scatterlists will be
259 : * chained in units of @max_ents.
260 : *
261 : * Notes:
262 : * If this function returns non-0 (eg failure), the caller must call
263 : * __sg_free_table() to cleanup any leftover allocations.
264 : *
265 : **/
266 0 : int __sg_alloc_table(struct sg_table *table, unsigned int nents,
267 : unsigned int max_ents, struct scatterlist *first_chunk,
268 : unsigned int nents_first_chunk, gfp_t gfp_mask,
269 : sg_alloc_fn *alloc_fn)
270 : {
271 0 : struct scatterlist *sg, *prv;
272 0 : unsigned int left;
273 0 : unsigned curr_max_ents = nents_first_chunk ?: max_ents;
274 0 : unsigned prv_max_ents;
275 :
276 0 : memset(table, 0, sizeof(*table));
277 :
278 0 : if (nents == 0)
279 : return -EINVAL;
280 : #ifdef CONFIG_ARCH_NO_SG_CHAIN
281 : if (WARN_ON_ONCE(nents > max_ents))
282 : return -EINVAL;
283 : #endif
284 :
285 : left = nents;
286 : prv = NULL;
287 0 : do {
288 0 : unsigned int sg_size, alloc_size = left;
289 :
290 0 : if (alloc_size > curr_max_ents) {
291 0 : alloc_size = curr_max_ents;
292 0 : sg_size = alloc_size - 1;
293 : } else
294 : sg_size = alloc_size;
295 :
296 0 : left -= sg_size;
297 :
298 0 : if (first_chunk) {
299 : sg = first_chunk;
300 : first_chunk = NULL;
301 : } else {
302 0 : sg = alloc_fn(alloc_size, gfp_mask);
303 : }
304 0 : if (unlikely(!sg)) {
305 : /*
306 : * Adjust entry count to reflect that the last
307 : * entry of the previous table won't be used for
308 : * linkage. Without this, sg_kfree() may get
309 : * confused.
310 : */
311 0 : if (prv)
312 0 : table->nents = ++table->orig_nents;
313 :
314 0 : return -ENOMEM;
315 : }
316 :
317 0 : sg_init_table(sg, alloc_size);
318 0 : table->nents = table->orig_nents += sg_size;
319 :
320 : /*
321 : * If this is the first mapping, assign the sg table header.
322 : * If this is not the first mapping, chain previous part.
323 : */
324 0 : if (prv)
325 0 : sg_chain(prv, prv_max_ents, sg);
326 : else
327 0 : table->sgl = sg;
328 :
329 : /*
330 : * If no more entries after this one, mark the end
331 : */
332 0 : if (!left)
333 0 : sg_mark_end(&sg[sg_size - 1]);
334 :
335 0 : prv = sg;
336 0 : prv_max_ents = curr_max_ents;
337 0 : curr_max_ents = max_ents;
338 0 : } while (left);
339 :
340 : return 0;
341 : }
342 : EXPORT_SYMBOL(__sg_alloc_table);
343 :
344 : /**
345 : * sg_alloc_table - Allocate and initialize an sg table
346 : * @table: The sg table header to use
347 : * @nents: Number of entries in sg list
348 : * @gfp_mask: GFP allocation mask
349 : *
350 : * Description:
351 : * Allocate and initialize an sg table. If @nents@ is larger than
352 : * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
353 : *
354 : **/
355 0 : int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
356 : {
357 0 : int ret;
358 :
359 0 : ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
360 : NULL, 0, gfp_mask, sg_kmalloc);
361 0 : if (unlikely(ret))
362 0 : __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
363 :
364 0 : return ret;
365 : }
366 : EXPORT_SYMBOL(sg_alloc_table);
367 :
368 0 : static struct scatterlist *get_next_sg(struct sg_table *table,
369 : struct scatterlist *cur,
370 : unsigned long needed_sges,
371 : gfp_t gfp_mask)
372 : {
373 0 : struct scatterlist *new_sg, *next_sg;
374 0 : unsigned int alloc_size;
375 :
376 0 : if (cur) {
377 0 : next_sg = sg_next(cur);
378 : /* Check if last entry should be keeped for chainning */
379 0 : if (!sg_is_last(next_sg) || needed_sges == 1)
380 : return next_sg;
381 : }
382 :
383 0 : alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC);
384 0 : new_sg = sg_kmalloc(alloc_size, gfp_mask);
385 0 : if (!new_sg)
386 0 : return ERR_PTR(-ENOMEM);
387 0 : sg_init_table(new_sg, alloc_size);
388 0 : if (cur) {
389 0 : __sg_chain(next_sg, new_sg);
390 0 : table->orig_nents += alloc_size - 1;
391 : } else {
392 0 : table->sgl = new_sg;
393 0 : table->orig_nents = alloc_size;
394 0 : table->nents = 0;
395 : }
396 : return new_sg;
397 : }
398 :
399 : /**
400 : * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
401 : * an array of pages
402 : * @sgt: The sg table header to use
403 : * @pages: Pointer to an array of page pointers
404 : * @n_pages: Number of pages in the pages array
405 : * @offset: Offset from start of the first page to the start of a buffer
406 : * @size: Number of valid bytes in the buffer (after offset)
407 : * @max_segment: Maximum size of a scatterlist element in bytes
408 : * @prv: Last populated sge in sgt
409 : * @left_pages: Left pages caller have to set after this call
410 : * @gfp_mask: GFP allocation mask
411 : *
412 : * Description:
413 : * If @prv is NULL, allocate and initialize an sg table from a list of pages,
414 : * else reuse the scatterlist passed in at @prv.
415 : * Contiguous ranges of the pages are squashed into a single scatterlist
416 : * entry up to the maximum size specified in @max_segment. A user may
417 : * provide an offset at a start and a size of valid data in a buffer
418 : * specified by the page array.
419 : *
420 : * Returns:
421 : * Last SGE in sgt on success, PTR_ERR on otherwise.
422 : * The allocation in @sgt must be released by sg_free_table.
423 : *
424 : * Notes:
425 : * If this function returns non-0 (eg failure), the caller must call
426 : * sg_free_table() to cleanup any leftover allocations.
427 : */
428 0 : struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt,
429 : struct page **pages, unsigned int n_pages, unsigned int offset,
430 : unsigned long size, unsigned int max_segment,
431 : struct scatterlist *prv, unsigned int left_pages,
432 : gfp_t gfp_mask)
433 : {
434 0 : unsigned int chunks, cur_page, seg_len, i, prv_len = 0;
435 0 : unsigned int added_nents = 0;
436 0 : struct scatterlist *s = prv;
437 :
438 : /*
439 : * The algorithm below requires max_segment to be aligned to PAGE_SIZE
440 : * otherwise it can overshoot.
441 : */
442 0 : max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE);
443 0 : if (WARN_ON(max_segment < PAGE_SIZE))
444 0 : return ERR_PTR(-EINVAL);
445 :
446 0 : if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && prv)
447 : return ERR_PTR(-EOPNOTSUPP);
448 :
449 0 : if (prv) {
450 0 : unsigned long paddr = (page_to_pfn(sg_page(prv)) * PAGE_SIZE +
451 0 : prv->offset + prv->length) /
452 : PAGE_SIZE;
453 :
454 0 : if (WARN_ON(offset))
455 0 : return ERR_PTR(-EINVAL);
456 :
457 : /* Merge contiguous pages into the last SG */
458 0 : prv_len = prv->length;
459 0 : while (n_pages && page_to_pfn(pages[0]) == paddr) {
460 0 : if (prv->length + PAGE_SIZE > max_segment)
461 : break;
462 0 : prv->length += PAGE_SIZE;
463 0 : paddr++;
464 0 : pages++;
465 0 : n_pages--;
466 : }
467 0 : if (!n_pages)
468 0 : goto out;
469 : }
470 :
471 : /* compute number of contiguous chunks */
472 0 : chunks = 1;
473 0 : seg_len = 0;
474 0 : for (i = 1; i < n_pages; i++) {
475 0 : seg_len += PAGE_SIZE;
476 0 : if (seg_len >= max_segment ||
477 0 : page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
478 0 : chunks++;
479 0 : seg_len = 0;
480 : }
481 : }
482 :
483 : /* merging chunks and putting them into the scatterlist */
484 : cur_page = 0;
485 0 : for (i = 0; i < chunks; i++) {
486 0 : unsigned int j, chunk_size;
487 :
488 : /* look for the end of the current chunk */
489 0 : seg_len = 0;
490 0 : for (j = cur_page + 1; j < n_pages; j++) {
491 0 : seg_len += PAGE_SIZE;
492 0 : if (seg_len >= max_segment ||
493 0 : page_to_pfn(pages[j]) !=
494 0 : page_to_pfn(pages[j - 1]) + 1)
495 : break;
496 : }
497 :
498 : /* Pass how many chunks might be left */
499 0 : s = get_next_sg(sgt, s, chunks - i + left_pages, gfp_mask);
500 0 : if (IS_ERR(s)) {
501 : /*
502 : * Adjust entry length to be as before function was
503 : * called.
504 : */
505 0 : if (prv)
506 0 : prv->length = prv_len;
507 0 : return s;
508 : }
509 0 : chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
510 0 : sg_set_page(s, pages[cur_page],
511 0 : min_t(unsigned long, size, chunk_size), offset);
512 0 : added_nents++;
513 0 : size -= chunk_size;
514 0 : offset = 0;
515 0 : cur_page = j;
516 : }
517 0 : sgt->nents += added_nents;
518 0 : out:
519 0 : if (!left_pages)
520 0 : sg_mark_end(s);
521 : return s;
522 : }
523 : EXPORT_SYMBOL(__sg_alloc_table_from_pages);
524 :
525 : /**
526 : * sg_alloc_table_from_pages - Allocate and initialize an sg table from
527 : * an array of pages
528 : * @sgt: The sg table header to use
529 : * @pages: Pointer to an array of page pointers
530 : * @n_pages: Number of pages in the pages array
531 : * @offset: Offset from start of the first page to the start of a buffer
532 : * @size: Number of valid bytes in the buffer (after offset)
533 : * @gfp_mask: GFP allocation mask
534 : *
535 : * Description:
536 : * Allocate and initialize an sg table from a list of pages. Contiguous
537 : * ranges of the pages are squashed into a single scatterlist node. A user
538 : * may provide an offset at a start and a size of valid data in a buffer
539 : * specified by the page array. The returned sg table is released by
540 : * sg_free_table.
541 : *
542 : * Returns:
543 : * 0 on success, negative error on failure
544 : */
545 0 : int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
546 : unsigned int n_pages, unsigned int offset,
547 : unsigned long size, gfp_t gfp_mask)
548 : {
549 0 : return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages,
550 : offset, size, UINT_MAX, NULL, 0, gfp_mask));
551 : }
552 : EXPORT_SYMBOL(sg_alloc_table_from_pages);
553 :
554 : #ifdef CONFIG_SGL_ALLOC
555 :
556 : /**
557 : * sgl_alloc_order - allocate a scatterlist and its pages
558 : * @length: Length in bytes of the scatterlist. Must be at least one
559 : * @order: Second argument for alloc_pages()
560 : * @chainable: Whether or not to allocate an extra element in the scatterlist
561 : * for scatterlist chaining purposes
562 : * @gfp: Memory allocation flags
563 : * @nent_p: [out] Number of entries in the scatterlist that have pages
564 : *
565 : * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
566 : */
567 0 : struct scatterlist *sgl_alloc_order(unsigned long long length,
568 : unsigned int order, bool chainable,
569 : gfp_t gfp, unsigned int *nent_p)
570 : {
571 0 : struct scatterlist *sgl, *sg;
572 0 : struct page *page;
573 0 : unsigned int nent, nalloc;
574 0 : u32 elem_len;
575 :
576 0 : nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
577 : /* Check for integer overflow */
578 0 : if (length > (nent << (PAGE_SHIFT + order)))
579 : return NULL;
580 0 : nalloc = nent;
581 0 : if (chainable) {
582 : /* Check for integer overflow */
583 0 : if (nalloc + 1 < nalloc)
584 : return NULL;
585 0 : nalloc++;
586 : }
587 0 : sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
588 : gfp & ~GFP_DMA);
589 0 : if (!sgl)
590 : return NULL;
591 :
592 0 : sg_init_table(sgl, nalloc);
593 0 : sg = sgl;
594 0 : while (length) {
595 0 : elem_len = min_t(u64, length, PAGE_SIZE << order);
596 0 : page = alloc_pages(gfp, order);
597 0 : if (!page) {
598 0 : sgl_free_order(sgl, order);
599 0 : return NULL;
600 : }
601 :
602 0 : sg_set_page(sg, page, elem_len, 0);
603 0 : length -= elem_len;
604 0 : sg = sg_next(sg);
605 : }
606 0 : WARN_ONCE(length, "length = %lld\n", length);
607 0 : if (nent_p)
608 0 : *nent_p = nent;
609 : return sgl;
610 : }
611 : EXPORT_SYMBOL(sgl_alloc_order);
612 :
613 : /**
614 : * sgl_alloc - allocate a scatterlist and its pages
615 : * @length: Length in bytes of the scatterlist
616 : * @gfp: Memory allocation flags
617 : * @nent_p: [out] Number of entries in the scatterlist
618 : *
619 : * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
620 : */
621 0 : struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
622 : unsigned int *nent_p)
623 : {
624 0 : return sgl_alloc_order(length, 0, false, gfp, nent_p);
625 : }
626 : EXPORT_SYMBOL(sgl_alloc);
627 :
628 : /**
629 : * sgl_free_n_order - free a scatterlist and its pages
630 : * @sgl: Scatterlist with one or more elements
631 : * @nents: Maximum number of elements to free
632 : * @order: Second argument for __free_pages()
633 : *
634 : * Notes:
635 : * - If several scatterlists have been chained and each chain element is
636 : * freed separately then it's essential to set nents correctly to avoid that a
637 : * page would get freed twice.
638 : * - All pages in a chained scatterlist can be freed at once by setting @nents
639 : * to a high number.
640 : */
641 0 : void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
642 : {
643 0 : struct scatterlist *sg;
644 0 : struct page *page;
645 0 : int i;
646 :
647 0 : for_each_sg(sgl, sg, nents, i) {
648 0 : if (!sg)
649 : break;
650 0 : page = sg_page(sg);
651 0 : if (page)
652 0 : __free_pages(page, order);
653 : }
654 0 : kfree(sgl);
655 0 : }
656 : EXPORT_SYMBOL(sgl_free_n_order);
657 :
658 : /**
659 : * sgl_free_order - free a scatterlist and its pages
660 : * @sgl: Scatterlist with one or more elements
661 : * @order: Second argument for __free_pages()
662 : */
663 0 : void sgl_free_order(struct scatterlist *sgl, int order)
664 : {
665 0 : sgl_free_n_order(sgl, INT_MAX, order);
666 0 : }
667 : EXPORT_SYMBOL(sgl_free_order);
668 :
669 : /**
670 : * sgl_free - free a scatterlist and its pages
671 : * @sgl: Scatterlist with one or more elements
672 : */
673 0 : void sgl_free(struct scatterlist *sgl)
674 : {
675 0 : sgl_free_order(sgl, 0);
676 0 : }
677 : EXPORT_SYMBOL(sgl_free);
678 :
679 : #endif /* CONFIG_SGL_ALLOC */
680 :
681 0 : void __sg_page_iter_start(struct sg_page_iter *piter,
682 : struct scatterlist *sglist, unsigned int nents,
683 : unsigned long pgoffset)
684 : {
685 0 : piter->__pg_advance = 0;
686 0 : piter->__nents = nents;
687 :
688 0 : piter->sg = sglist;
689 0 : piter->sg_pgoffset = pgoffset;
690 0 : }
691 : EXPORT_SYMBOL(__sg_page_iter_start);
692 :
693 0 : static int sg_page_count(struct scatterlist *sg)
694 : {
695 0 : return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
696 : }
697 :
698 0 : bool __sg_page_iter_next(struct sg_page_iter *piter)
699 : {
700 0 : if (!piter->__nents || !piter->sg)
701 : return false;
702 :
703 0 : piter->sg_pgoffset += piter->__pg_advance;
704 0 : piter->__pg_advance = 1;
705 :
706 0 : while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
707 0 : piter->sg_pgoffset -= sg_page_count(piter->sg);
708 0 : piter->sg = sg_next(piter->sg);
709 0 : if (!--piter->__nents || !piter->sg)
710 : return false;
711 : }
712 :
713 : return true;
714 : }
715 : EXPORT_SYMBOL(__sg_page_iter_next);
716 :
717 0 : static int sg_dma_page_count(struct scatterlist *sg)
718 : {
719 0 : return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT;
720 : }
721 :
722 0 : bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter)
723 : {
724 0 : struct sg_page_iter *piter = &dma_iter->base;
725 :
726 0 : if (!piter->__nents || !piter->sg)
727 : return false;
728 :
729 0 : piter->sg_pgoffset += piter->__pg_advance;
730 0 : piter->__pg_advance = 1;
731 :
732 0 : while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) {
733 0 : piter->sg_pgoffset -= sg_dma_page_count(piter->sg);
734 0 : piter->sg = sg_next(piter->sg);
735 0 : if (!--piter->__nents || !piter->sg)
736 : return false;
737 : }
738 :
739 : return true;
740 : }
741 : EXPORT_SYMBOL(__sg_page_iter_dma_next);
742 :
743 : /**
744 : * sg_miter_start - start mapping iteration over a sg list
745 : * @miter: sg mapping iter to be started
746 : * @sgl: sg list to iterate over
747 : * @nents: number of sg entries
748 : *
749 : * Description:
750 : * Starts mapping iterator @miter.
751 : *
752 : * Context:
753 : * Don't care.
754 : */
755 0 : void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
756 : unsigned int nents, unsigned int flags)
757 : {
758 0 : memset(miter, 0, sizeof(struct sg_mapping_iter));
759 :
760 0 : __sg_page_iter_start(&miter->piter, sgl, nents, 0);
761 0 : WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
762 0 : miter->__flags = flags;
763 0 : }
764 : EXPORT_SYMBOL(sg_miter_start);
765 :
766 0 : static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
767 : {
768 0 : if (!miter->__remaining) {
769 0 : struct scatterlist *sg;
770 :
771 0 : if (!__sg_page_iter_next(&miter->piter))
772 : return false;
773 :
774 0 : sg = miter->piter.sg;
775 :
776 0 : miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset;
777 0 : miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT;
778 0 : miter->__offset &= PAGE_SIZE - 1;
779 0 : miter->__remaining = sg->offset + sg->length -
780 0 : (miter->piter.sg_pgoffset << PAGE_SHIFT) -
781 : miter->__offset;
782 0 : miter->__remaining = min_t(unsigned long, miter->__remaining,
783 : PAGE_SIZE - miter->__offset);
784 : }
785 :
786 : return true;
787 : }
788 :
789 : /**
790 : * sg_miter_skip - reposition mapping iterator
791 : * @miter: sg mapping iter to be skipped
792 : * @offset: number of bytes to plus the current location
793 : *
794 : * Description:
795 : * Sets the offset of @miter to its current location plus @offset bytes.
796 : * If mapping iterator @miter has been proceeded by sg_miter_next(), this
797 : * stops @miter.
798 : *
799 : * Context:
800 : * Don't care if @miter is stopped, or not proceeded yet.
801 : * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
802 : *
803 : * Returns:
804 : * true if @miter contains the valid mapping. false if end of sg
805 : * list is reached.
806 : */
807 0 : bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
808 : {
809 0 : sg_miter_stop(miter);
810 :
811 0 : while (offset) {
812 0 : off_t consumed;
813 :
814 0 : if (!sg_miter_get_next_page(miter))
815 : return false;
816 :
817 0 : consumed = min_t(off_t, offset, miter->__remaining);
818 0 : miter->__offset += consumed;
819 0 : miter->__remaining -= consumed;
820 0 : offset -= consumed;
821 : }
822 :
823 : return true;
824 : }
825 : EXPORT_SYMBOL(sg_miter_skip);
826 :
827 : /**
828 : * sg_miter_next - proceed mapping iterator to the next mapping
829 : * @miter: sg mapping iter to proceed
830 : *
831 : * Description:
832 : * Proceeds @miter to the next mapping. @miter should have been started
833 : * using sg_miter_start(). On successful return, @miter->page,
834 : * @miter->addr and @miter->length point to the current mapping.
835 : *
836 : * Context:
837 : * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
838 : * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
839 : *
840 : * Returns:
841 : * true if @miter contains the next mapping. false if end of sg
842 : * list is reached.
843 : */
844 0 : bool sg_miter_next(struct sg_mapping_iter *miter)
845 : {
846 0 : sg_miter_stop(miter);
847 :
848 : /*
849 : * Get to the next page if necessary.
850 : * __remaining, __offset is adjusted by sg_miter_stop
851 : */
852 0 : if (!sg_miter_get_next_page(miter))
853 : return false;
854 :
855 0 : miter->page = sg_page_iter_page(&miter->piter);
856 0 : miter->consumed = miter->length = miter->__remaining;
857 :
858 0 : if (miter->__flags & SG_MITER_ATOMIC)
859 0 : miter->addr = kmap_atomic(miter->page) + miter->__offset;
860 : else
861 0 : miter->addr = kmap(miter->page) + miter->__offset;
862 :
863 : return true;
864 : }
865 : EXPORT_SYMBOL(sg_miter_next);
866 :
867 : /**
868 : * sg_miter_stop - stop mapping iteration
869 : * @miter: sg mapping iter to be stopped
870 : *
871 : * Description:
872 : * Stops mapping iterator @miter. @miter should have been started
873 : * using sg_miter_start(). A stopped iteration can be resumed by
874 : * calling sg_miter_next() on it. This is useful when resources (kmap)
875 : * need to be released during iteration.
876 : *
877 : * Context:
878 : * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
879 : * otherwise.
880 : */
881 0 : void sg_miter_stop(struct sg_mapping_iter *miter)
882 : {
883 0 : WARN_ON(miter->consumed > miter->length);
884 :
885 : /* drop resources from the last iteration */
886 0 : if (miter->addr) {
887 0 : miter->__offset += miter->consumed;
888 0 : miter->__remaining -= miter->consumed;
889 :
890 0 : if ((miter->__flags & SG_MITER_TO_SG) &&
891 0 : !PageSlab(miter->page))
892 0 : flush_kernel_dcache_page(miter->page);
893 :
894 0 : if (miter->__flags & SG_MITER_ATOMIC) {
895 0 : WARN_ON_ONCE(preemptible());
896 0 : kunmap_atomic(miter->addr);
897 : } else
898 0 : kunmap(miter->page);
899 :
900 0 : miter->page = NULL;
901 0 : miter->addr = NULL;
902 0 : miter->length = 0;
903 0 : miter->consumed = 0;
904 : }
905 0 : }
906 : EXPORT_SYMBOL(sg_miter_stop);
907 :
908 : /**
909 : * sg_copy_buffer - Copy data between a linear buffer and an SG list
910 : * @sgl: The SG list
911 : * @nents: Number of SG entries
912 : * @buf: Where to copy from
913 : * @buflen: The number of bytes to copy
914 : * @skip: Number of bytes to skip before copying
915 : * @to_buffer: transfer direction (true == from an sg list to a
916 : * buffer, false == from a buffer to an sg list)
917 : *
918 : * Returns the number of copied bytes.
919 : *
920 : **/
921 0 : size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
922 : size_t buflen, off_t skip, bool to_buffer)
923 : {
924 0 : unsigned int offset = 0;
925 0 : struct sg_mapping_iter miter;
926 0 : unsigned int sg_flags = SG_MITER_ATOMIC;
927 :
928 0 : if (to_buffer)
929 : sg_flags |= SG_MITER_FROM_SG;
930 : else
931 0 : sg_flags |= SG_MITER_TO_SG;
932 :
933 0 : sg_miter_start(&miter, sgl, nents, sg_flags);
934 :
935 0 : if (!sg_miter_skip(&miter, skip))
936 : return 0;
937 :
938 0 : while ((offset < buflen) && sg_miter_next(&miter)) {
939 0 : unsigned int len;
940 :
941 0 : len = min(miter.length, buflen - offset);
942 :
943 0 : if (to_buffer)
944 0 : memcpy(buf + offset, miter.addr, len);
945 : else
946 0 : memcpy(miter.addr, buf + offset, len);
947 :
948 0 : offset += len;
949 : }
950 :
951 0 : sg_miter_stop(&miter);
952 :
953 0 : return offset;
954 : }
955 : EXPORT_SYMBOL(sg_copy_buffer);
956 :
957 : /**
958 : * sg_copy_from_buffer - Copy from a linear buffer to an SG list
959 : * @sgl: The SG list
960 : * @nents: Number of SG entries
961 : * @buf: Where to copy from
962 : * @buflen: The number of bytes to copy
963 : *
964 : * Returns the number of copied bytes.
965 : *
966 : **/
967 0 : size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
968 : const void *buf, size_t buflen)
969 : {
970 0 : return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
971 : }
972 : EXPORT_SYMBOL(sg_copy_from_buffer);
973 :
974 : /**
975 : * sg_copy_to_buffer - Copy from an SG list to a linear buffer
976 : * @sgl: The SG list
977 : * @nents: Number of SG entries
978 : * @buf: Where to copy to
979 : * @buflen: The number of bytes to copy
980 : *
981 : * Returns the number of copied bytes.
982 : *
983 : **/
984 0 : size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
985 : void *buf, size_t buflen)
986 : {
987 0 : return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
988 : }
989 : EXPORT_SYMBOL(sg_copy_to_buffer);
990 :
991 : /**
992 : * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
993 : * @sgl: The SG list
994 : * @nents: Number of SG entries
995 : * @buf: Where to copy from
996 : * @buflen: The number of bytes to copy
997 : * @skip: Number of bytes to skip before copying
998 : *
999 : * Returns the number of copied bytes.
1000 : *
1001 : **/
1002 0 : size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
1003 : const void *buf, size_t buflen, off_t skip)
1004 : {
1005 0 : return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
1006 : }
1007 : EXPORT_SYMBOL(sg_pcopy_from_buffer);
1008 :
1009 : /**
1010 : * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
1011 : * @sgl: The SG list
1012 : * @nents: Number of SG entries
1013 : * @buf: Where to copy to
1014 : * @buflen: The number of bytes to copy
1015 : * @skip: Number of bytes to skip before copying
1016 : *
1017 : * Returns the number of copied bytes.
1018 : *
1019 : **/
1020 0 : size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
1021 : void *buf, size_t buflen, off_t skip)
1022 : {
1023 0 : return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
1024 : }
1025 : EXPORT_SYMBOL(sg_pcopy_to_buffer);
1026 :
1027 : /**
1028 : * sg_zero_buffer - Zero-out a part of a SG list
1029 : * @sgl: The SG list
1030 : * @nents: Number of SG entries
1031 : * @buflen: The number of bytes to zero out
1032 : * @skip: Number of bytes to skip before zeroing
1033 : *
1034 : * Returns the number of bytes zeroed.
1035 : **/
1036 0 : size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
1037 : size_t buflen, off_t skip)
1038 : {
1039 0 : unsigned int offset = 0;
1040 0 : struct sg_mapping_iter miter;
1041 0 : unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
1042 :
1043 0 : sg_miter_start(&miter, sgl, nents, sg_flags);
1044 :
1045 0 : if (!sg_miter_skip(&miter, skip))
1046 : return false;
1047 :
1048 0 : while (offset < buflen && sg_miter_next(&miter)) {
1049 0 : unsigned int len;
1050 :
1051 0 : len = min(miter.length, buflen - offset);
1052 0 : memset(miter.addr, 0, len);
1053 :
1054 0 : offset += len;
1055 : }
1056 :
1057 0 : sg_miter_stop(&miter);
1058 0 : return offset;
1059 : }
1060 : EXPORT_SYMBOL(sg_zero_buffer);
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