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1 | /* | |
2 | * linux/fs/seq_file.c | |
3 | * | |
4 | * helper functions for making synthetic files from sequences of records. | |
5 | * initial implementation -- AV, Oct 2001. | |
6 | */ | |
7 | ||
8 | #include <linux/fs.h> | |
9 | #include <linux/module.h> | |
10 | #include <linux/seq_file.h> | |
11 | #include <linux/slab.h> | |
12 | ||
13 | #include <asm/uaccess.h> | |
14 | #include <asm/page.h> | |
15 | ||
16 | /** | |
17 | * seq_open - initialize sequential file | |
18 | * @file: file we initialize | |
19 | * @op: method table describing the sequence | |
20 | * | |
21 | * seq_open() sets @file, associating it with a sequence described | |
22 | * by @op. @op->start() sets the iterator up and returns the first | |
23 | * element of sequence. @op->stop() shuts it down. @op->next() | |
24 | * returns the next element of sequence. @op->show() prints element | |
25 | * into the buffer. In case of error ->start() and ->next() return | |
26 | * ERR_PTR(error). In the end of sequence they return %NULL. ->show() | |
27 | * returns 0 in case of success and negative number in case of error. | |
28 | * Returning SEQ_SKIP means "discard this element and move on". | |
29 | */ | |
30 | int seq_open(struct file *file, const struct seq_operations *op) | |
31 | { | |
32 | struct seq_file *p = file->private_data; | |
33 | ||
34 | if (!p) { | |
35 | p = kmalloc(sizeof(*p), GFP_KERNEL); | |
36 | if (!p) | |
37 | return -ENOMEM; | |
38 | file->private_data = p; | |
39 | } | |
40 | memset(p, 0, sizeof(*p)); | |
41 | mutex_init(&p->lock); | |
42 | p->op = op; | |
43 | ||
44 | /* | |
45 | * Wrappers around seq_open(e.g. swaps_open) need to be | |
46 | * aware of this. If they set f_version themselves, they | |
47 | * should call seq_open first and then set f_version. | |
48 | */ | |
49 | file->f_version = 0; | |
50 | ||
51 | /* | |
52 | * seq_files support lseek() and pread(). They do not implement | |
53 | * write() at all, but we clear FMODE_PWRITE here for historical | |
54 | * reasons. | |
55 | * | |
56 | * If a client of seq_files a) implements file.write() and b) wishes to | |
57 | * support pwrite() then that client will need to implement its own | |
58 | * file.open() which calls seq_open() and then sets FMODE_PWRITE. | |
59 | */ | |
60 | file->f_mode &= ~FMODE_PWRITE; | |
61 | return 0; | |
62 | } | |
63 | EXPORT_SYMBOL(seq_open); | |
64 | ||
65 | static int traverse(struct seq_file *m, loff_t offset) | |
66 | { | |
67 | loff_t pos = 0, index; | |
68 | int error = 0; | |
69 | void *p; | |
70 | ||
71 | m->version = 0; | |
72 | index = 0; | |
73 | m->count = m->from = 0; | |
74 | if (!offset) { | |
75 | m->index = index; | |
76 | return 0; | |
77 | } | |
78 | if (!m->buf) { | |
79 | m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); | |
80 | if (!m->buf) | |
81 | return -ENOMEM; | |
82 | } | |
83 | p = m->op->start(m, &index); | |
84 | while (p) { | |
85 | error = PTR_ERR(p); | |
86 | if (IS_ERR(p)) | |
87 | break; | |
88 | error = m->op->show(m, p); | |
89 | if (error < 0) | |
90 | break; | |
91 | if (unlikely(error)) { | |
92 | error = 0; | |
93 | m->count = 0; | |
94 | } | |
95 | if (m->count == m->size) | |
96 | goto Eoverflow; | |
97 | if (pos + m->count > offset) { | |
98 | m->from = offset - pos; | |
99 | m->count -= m->from; | |
100 | m->index = index; | |
101 | break; | |
102 | } | |
103 | pos += m->count; | |
104 | m->count = 0; | |
105 | if (pos == offset) { | |
106 | index++; | |
107 | m->index = index; | |
108 | break; | |
109 | } | |
110 | p = m->op->next(m, p, &index); | |
111 | } | |
112 | m->op->stop(m, p); | |
113 | m->index = index; | |
114 | return error; | |
115 | ||
116 | Eoverflow: | |
117 | m->op->stop(m, p); | |
118 | kfree(m->buf); | |
119 | m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); | |
120 | return !m->buf ? -ENOMEM : -EAGAIN; | |
121 | } | |
122 | ||
123 | /** | |
124 | * seq_read - ->read() method for sequential files. | |
125 | * @file: the file to read from | |
126 | * @buf: the buffer to read to | |
127 | * @size: the maximum number of bytes to read | |
128 | * @ppos: the current position in the file | |
129 | * | |
130 | * Ready-made ->f_op->read() | |
131 | */ | |
132 | ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) | |
133 | { | |
134 | struct seq_file *m = (struct seq_file *)file->private_data; | |
135 | size_t copied = 0; | |
136 | loff_t pos; | |
137 | size_t n; | |
138 | void *p; | |
139 | int err = 0; | |
140 | ||
141 | mutex_lock(&m->lock); | |
142 | ||
143 | /* Don't assume *ppos is where we left it */ | |
144 | if (unlikely(*ppos != m->read_pos)) { | |
145 | m->read_pos = *ppos; | |
146 | while ((err = traverse(m, *ppos)) == -EAGAIN) | |
147 | ; | |
148 | if (err) { | |
149 | /* With prejudice... */ | |
150 | m->read_pos = 0; | |
151 | m->version = 0; | |
152 | m->index = 0; | |
153 | m->count = 0; | |
154 | goto Done; | |
155 | } | |
156 | } | |
157 | ||
158 | /* | |
159 | * seq_file->op->..m_start/m_stop/m_next may do special actions | |
160 | * or optimisations based on the file->f_version, so we want to | |
161 | * pass the file->f_version to those methods. | |
162 | * | |
163 | * seq_file->version is just copy of f_version, and seq_file | |
164 | * methods can treat it simply as file version. | |
165 | * It is copied in first and copied out after all operations. | |
166 | * It is convenient to have it as part of structure to avoid the | |
167 | * need of passing another argument to all the seq_file methods. | |
168 | */ | |
169 | m->version = file->f_version; | |
170 | /* grab buffer if we didn't have one */ | |
171 | if (!m->buf) { | |
172 | m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); | |
173 | if (!m->buf) | |
174 | goto Enomem; | |
175 | } | |
176 | /* if not empty - flush it first */ | |
177 | if (m->count) { | |
178 | n = min(m->count, size); | |
179 | err = copy_to_user(buf, m->buf + m->from, n); | |
180 | if (err) | |
181 | goto Efault; | |
182 | m->count -= n; | |
183 | m->from += n; | |
184 | size -= n; | |
185 | buf += n; | |
186 | copied += n; | |
187 | if (!m->count) | |
188 | m->index++; | |
189 | if (!size) | |
190 | goto Done; | |
191 | } | |
192 | /* we need at least one record in buffer */ | |
193 | pos = m->index; | |
194 | p = m->op->start(m, &pos); | |
195 | while (1) { | |
196 | err = PTR_ERR(p); | |
197 | if (!p || IS_ERR(p)) | |
198 | break; | |
199 | err = m->op->show(m, p); | |
200 | if (err < 0) | |
201 | break; | |
202 | if (unlikely(err)) | |
203 | m->count = 0; | |
204 | if (unlikely(!m->count)) { | |
205 | p = m->op->next(m, p, &pos); | |
206 | m->index = pos; | |
207 | continue; | |
208 | } | |
209 | if (m->count < m->size) | |
210 | goto Fill; | |
211 | m->op->stop(m, p); | |
212 | kfree(m->buf); | |
213 | m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); | |
214 | if (!m->buf) | |
215 | goto Enomem; | |
216 | m->count = 0; | |
217 | m->version = 0; | |
218 | pos = m->index; | |
219 | p = m->op->start(m, &pos); | |
220 | } | |
221 | m->op->stop(m, p); | |
222 | m->count = 0; | |
223 | goto Done; | |
224 | Fill: | |
225 | /* they want more? let's try to get some more */ | |
226 | while (m->count < size) { | |
227 | size_t offs = m->count; | |
228 | loff_t next = pos; | |
229 | p = m->op->next(m, p, &next); | |
230 | if (!p || IS_ERR(p)) { | |
231 | err = PTR_ERR(p); | |
232 | break; | |
233 | } | |
234 | err = m->op->show(m, p); | |
235 | if (m->count == m->size || err) { | |
236 | m->count = offs; | |
237 | if (likely(err <= 0)) | |
238 | break; | |
239 | } | |
240 | pos = next; | |
241 | } | |
242 | m->op->stop(m, p); | |
243 | n = min(m->count, size); | |
244 | err = copy_to_user(buf, m->buf, n); | |
245 | if (err) | |
246 | goto Efault; | |
247 | copied += n; | |
248 | m->count -= n; | |
249 | if (m->count) | |
250 | m->from = n; | |
251 | else | |
252 | pos++; | |
253 | m->index = pos; | |
254 | Done: | |
255 | if (!copied) | |
256 | copied = err; | |
257 | else { | |
258 | *ppos += copied; | |
259 | m->read_pos += copied; | |
260 | } | |
261 | file->f_version = m->version; | |
262 | mutex_unlock(&m->lock); | |
263 | return copied; | |
264 | Enomem: | |
265 | err = -ENOMEM; | |
266 | goto Done; | |
267 | Efault: | |
268 | err = -EFAULT; | |
269 | goto Done; | |
270 | } | |
271 | EXPORT_SYMBOL(seq_read); | |
272 | ||
273 | /** | |
274 | * seq_lseek - ->llseek() method for sequential files. | |
275 | * @file: the file in question | |
276 | * @offset: new position | |
277 | * @origin: 0 for absolute, 1 for relative position | |
278 | * | |
279 | * Ready-made ->f_op->llseek() | |
280 | */ | |
281 | loff_t seq_lseek(struct file *file, loff_t offset, int origin) | |
282 | { | |
283 | struct seq_file *m = (struct seq_file *)file->private_data; | |
284 | loff_t retval = -EINVAL; | |
285 | ||
286 | mutex_lock(&m->lock); | |
287 | m->version = file->f_version; | |
288 | switch (origin) { | |
289 | case 1: | |
290 | offset += file->f_pos; | |
291 | case 0: | |
292 | if (offset < 0) | |
293 | break; | |
294 | retval = offset; | |
295 | if (offset != m->read_pos) { | |
296 | while ((retval=traverse(m, offset)) == -EAGAIN) | |
297 | ; | |
298 | if (retval) { | |
299 | /* with extreme prejudice... */ | |
300 | file->f_pos = 0; | |
301 | m->read_pos = 0; | |
302 | m->version = 0; | |
303 | m->index = 0; | |
304 | m->count = 0; | |
305 | } else { | |
306 | m->read_pos = offset; | |
307 | retval = file->f_pos = offset; | |
308 | } | |
309 | } | |
310 | } | |
311 | file->f_version = m->version; | |
312 | mutex_unlock(&m->lock); | |
313 | return retval; | |
314 | } | |
315 | EXPORT_SYMBOL(seq_lseek); | |
316 | ||
317 | /** | |
318 | * seq_release - free the structures associated with sequential file. | |
319 | * @file: file in question | |
320 | * @inode: file->f_path.dentry->d_inode | |
321 | * | |
322 | * Frees the structures associated with sequential file; can be used | |
323 | * as ->f_op->release() if you don't have private data to destroy. | |
324 | */ | |
325 | int seq_release(struct inode *inode, struct file *file) | |
326 | { | |
327 | struct seq_file *m = (struct seq_file *)file->private_data; | |
328 | kfree(m->buf); | |
329 | kfree(m); | |
330 | return 0; | |
331 | } | |
332 | EXPORT_SYMBOL(seq_release); | |
333 | ||
334 | /** | |
335 | * seq_escape - print string into buffer, escaping some characters | |
336 | * @m: target buffer | |
337 | * @s: string | |
338 | * @esc: set of characters that need escaping | |
339 | * | |
340 | * Puts string into buffer, replacing each occurrence of character from | |
341 | * @esc with usual octal escape. Returns 0 in case of success, -1 - in | |
342 | * case of overflow. | |
343 | */ | |
344 | int seq_escape(struct seq_file *m, const char *s, const char *esc) | |
345 | { | |
346 | char *end = m->buf + m->size; | |
347 | char *p; | |
348 | char c; | |
349 | ||
350 | for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) { | |
351 | if (!strchr(esc, c)) { | |
352 | *p++ = c; | |
353 | continue; | |
354 | } | |
355 | if (p + 3 < end) { | |
356 | *p++ = '\\'; | |
357 | *p++ = '0' + ((c & 0300) >> 6); | |
358 | *p++ = '0' + ((c & 070) >> 3); | |
359 | *p++ = '0' + (c & 07); | |
360 | continue; | |
361 | } | |
362 | m->count = m->size; | |
363 | return -1; | |
364 | } | |
365 | m->count = p - m->buf; | |
366 | return 0; | |
367 | } | |
368 | EXPORT_SYMBOL(seq_escape); | |
369 | ||
370 | int seq_printf(struct seq_file *m, const char *f, ...) | |
371 | { | |
372 | va_list args; | |
373 | int len; | |
374 | ||
375 | if (m->count < m->size) { | |
376 | va_start(args, f); | |
377 | len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); | |
378 | va_end(args); | |
379 | if (m->count + len < m->size) { | |
380 | m->count += len; | |
381 | return 0; | |
382 | } | |
383 | } | |
384 | m->count = m->size; | |
385 | return -1; | |
386 | } | |
387 | EXPORT_SYMBOL(seq_printf); | |
388 | ||
389 | /** | |
390 | * mangle_path - mangle and copy path to buffer beginning | |
391 | * @s: buffer start | |
392 | * @p: beginning of path in above buffer | |
393 | * @esc: set of characters that need escaping | |
394 | * | |
395 | * Copy the path from @p to @s, replacing each occurrence of character from | |
396 | * @esc with usual octal escape. | |
397 | * Returns pointer past last written character in @s, or NULL in case of | |
398 | * failure. | |
399 | */ | |
400 | char *mangle_path(char *s, char *p, char *esc) | |
401 | { | |
402 | while (s <= p) { | |
403 | char c = *p++; | |
404 | if (!c) { | |
405 | return s; | |
406 | } else if (!strchr(esc, c)) { | |
407 | *s++ = c; | |
408 | } else if (s + 4 > p) { | |
409 | break; | |
410 | } else { | |
411 | *s++ = '\\'; | |
412 | *s++ = '0' + ((c & 0300) >> 6); | |
413 | *s++ = '0' + ((c & 070) >> 3); | |
414 | *s++ = '0' + (c & 07); | |
415 | } | |
416 | } | |
417 | return NULL; | |
418 | } | |
419 | EXPORT_SYMBOL(mangle_path); | |
420 | ||
421 | /** | |
422 | * seq_path - seq_file interface to print a pathname | |
423 | * @m: the seq_file handle | |
424 | * @path: the struct path to print | |
425 | * @esc: set of characters to escape in the output | |
426 | * | |
427 | * return the absolute path of 'path', as represented by the | |
428 | * dentry / mnt pair in the path parameter. | |
429 | */ | |
430 | int seq_path(struct seq_file *m, struct path *path, char *esc) | |
431 | { | |
432 | if (m->count < m->size) { | |
433 | char *s = m->buf + m->count; | |
434 | char *p = d_path(path, s, m->size - m->count); | |
435 | if (!IS_ERR(p)) { | |
436 | s = mangle_path(s, p, esc); | |
437 | if (s) { | |
438 | p = m->buf + m->count; | |
439 | m->count = s - m->buf; | |
440 | return s - p; | |
441 | } | |
442 | } | |
443 | } | |
444 | m->count = m->size; | |
445 | return -1; | |
446 | } | |
447 | EXPORT_SYMBOL(seq_path); | |
448 | ||
449 | /* | |
450 | * Same as seq_path, but relative to supplied root. | |
451 | * | |
452 | * root may be changed, see __d_path(). | |
453 | */ | |
454 | int seq_path_root(struct seq_file *m, struct path *path, struct path *root, | |
455 | char *esc) | |
456 | { | |
457 | int err = -ENAMETOOLONG; | |
458 | if (m->count < m->size) { | |
459 | char *s = m->buf + m->count; | |
460 | char *p; | |
461 | ||
462 | spin_lock(&dcache_lock); | |
463 | p = __d_path(path, root, s, m->size - m->count); | |
464 | spin_unlock(&dcache_lock); | |
465 | err = PTR_ERR(p); | |
466 | if (!IS_ERR(p)) { | |
467 | s = mangle_path(s, p, esc); | |
468 | if (s) { | |
469 | p = m->buf + m->count; | |
470 | m->count = s - m->buf; | |
471 | return 0; | |
472 | } | |
473 | err = -ENAMETOOLONG; | |
474 | } | |
475 | } | |
476 | m->count = m->size; | |
477 | return err; | |
478 | } | |
479 | ||
480 | /* | |
481 | * returns the path of the 'dentry' from the root of its filesystem. | |
482 | */ | |
483 | int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc) | |
484 | { | |
485 | if (m->count < m->size) { | |
486 | char *s = m->buf + m->count; | |
487 | char *p = dentry_path(dentry, s, m->size - m->count); | |
488 | if (!IS_ERR(p)) { | |
489 | s = mangle_path(s, p, esc); | |
490 | if (s) { | |
491 | p = m->buf + m->count; | |
492 | m->count = s - m->buf; | |
493 | return s - p; | |
494 | } | |
495 | } | |
496 | } | |
497 | m->count = m->size; | |
498 | return -1; | |
499 | } | |
500 | ||
501 | int seq_bitmap(struct seq_file *m, const unsigned long *bits, | |
502 | unsigned int nr_bits) | |
503 | { | |
504 | if (m->count < m->size) { | |
505 | int len = bitmap_scnprintf(m->buf + m->count, | |
506 | m->size - m->count, bits, nr_bits); | |
507 | if (m->count + len < m->size) { | |
508 | m->count += len; | |
509 | return 0; | |
510 | } | |
511 | } | |
512 | m->count = m->size; | |
513 | return -1; | |
514 | } | |
515 | EXPORT_SYMBOL(seq_bitmap); | |
516 | ||
517 | int seq_bitmap_list(struct seq_file *m, const unsigned long *bits, | |
518 | unsigned int nr_bits) | |
519 | { | |
520 | if (m->count < m->size) { | |
521 | int len = bitmap_scnlistprintf(m->buf + m->count, | |
522 | m->size - m->count, bits, nr_bits); | |
523 | if (m->count + len < m->size) { | |
524 | m->count += len; | |
525 | return 0; | |
526 | } | |
527 | } | |
528 | m->count = m->size; | |
529 | return -1; | |
530 | } | |
531 | EXPORT_SYMBOL(seq_bitmap_list); | |
532 | ||
533 | static void *single_start(struct seq_file *p, loff_t *pos) | |
534 | { | |
535 | return NULL + (*pos == 0); | |
536 | } | |
537 | ||
538 | static void *single_next(struct seq_file *p, void *v, loff_t *pos) | |
539 | { | |
540 | ++*pos; | |
541 | return NULL; | |
542 | } | |
543 | ||
544 | static void single_stop(struct seq_file *p, void *v) | |
545 | { | |
546 | } | |
547 | ||
548 | int single_open(struct file *file, int (*show)(struct seq_file *, void *), | |
549 | void *data) | |
550 | { | |
551 | struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL); | |
552 | int res = -ENOMEM; | |
553 | ||
554 | if (op) { | |
555 | op->start = single_start; | |
556 | op->next = single_next; | |
557 | op->stop = single_stop; | |
558 | op->show = show; | |
559 | res = seq_open(file, op); | |
560 | if (!res) | |
561 | ((struct seq_file *)file->private_data)->private = data; | |
562 | else | |
563 | kfree(op); | |
564 | } | |
565 | return res; | |
566 | } | |
567 | EXPORT_SYMBOL(single_open); | |
568 | ||
569 | int single_release(struct inode *inode, struct file *file) | |
570 | { | |
571 | const struct seq_operations *op = ((struct seq_file *)file->private_data)->op; | |
572 | int res = seq_release(inode, file); | |
573 | kfree(op); | |
574 | return res; | |
575 | } | |
576 | EXPORT_SYMBOL(single_release); | |
577 | ||
578 | int seq_release_private(struct inode *inode, struct file *file) | |
579 | { | |
580 | struct seq_file *seq = file->private_data; | |
581 | ||
582 | kfree(seq->private); | |
583 | seq->private = NULL; | |
584 | return seq_release(inode, file); | |
585 | } | |
586 | EXPORT_SYMBOL(seq_release_private); | |
587 | ||
588 | void *__seq_open_private(struct file *f, const struct seq_operations *ops, | |
589 | int psize) | |
590 | { | |
591 | int rc; | |
592 | void *private; | |
593 | struct seq_file *seq; | |
594 | ||
595 | private = kzalloc(psize, GFP_KERNEL); | |
596 | if (private == NULL) | |
597 | goto out; | |
598 | ||
599 | rc = seq_open(f, ops); | |
600 | if (rc < 0) | |
601 | goto out_free; | |
602 | ||
603 | seq = f->private_data; | |
604 | seq->private = private; | |
605 | return private; | |
606 | ||
607 | out_free: | |
608 | kfree(private); | |
609 | out: | |
610 | return NULL; | |
611 | } | |
612 | EXPORT_SYMBOL(__seq_open_private); | |
613 | ||
614 | int seq_open_private(struct file *filp, const struct seq_operations *ops, | |
615 | int psize) | |
616 | { | |
617 | return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM; | |
618 | } | |
619 | EXPORT_SYMBOL(seq_open_private); | |
620 | ||
621 | int seq_putc(struct seq_file *m, char c) | |
622 | { | |
623 | if (m->count < m->size) { | |
624 | m->buf[m->count++] = c; | |
625 | return 0; | |
626 | } | |
627 | return -1; | |
628 | } | |
629 | EXPORT_SYMBOL(seq_putc); | |
630 | ||
631 | int seq_puts(struct seq_file *m, const char *s) | |
632 | { | |
633 | int len = strlen(s); | |
634 | if (m->count + len < m->size) { | |
635 | memcpy(m->buf + m->count, s, len); | |
636 | m->count += len; | |
637 | return 0; | |
638 | } | |
639 | m->count = m->size; | |
640 | return -1; | |
641 | } | |
642 | EXPORT_SYMBOL(seq_puts); | |
643 | ||
644 | /** | |
645 | * seq_write - write arbitrary data to buffer | |
646 | * @seq: seq_file identifying the buffer to which data should be written | |
647 | * @data: data address | |
648 | * @len: number of bytes | |
649 | * | |
650 | * Return 0 on success, non-zero otherwise. | |
651 | */ | |
652 | int seq_write(struct seq_file *seq, const void *data, size_t len) | |
653 | { | |
654 | if (seq->count + len < seq->size) { | |
655 | memcpy(seq->buf + seq->count, data, len); | |
656 | seq->count += len; | |
657 | return 0; | |
658 | } | |
659 | seq->count = seq->size; | |
660 | return -1; | |
661 | } | |
662 | EXPORT_SYMBOL(seq_write); | |
663 | ||
664 | struct list_head *seq_list_start(struct list_head *head, loff_t pos) | |
665 | { | |
666 | struct list_head *lh; | |
667 | ||
668 | list_for_each(lh, head) | |
669 | if (pos-- == 0) | |
670 | return lh; | |
671 | ||
672 | return NULL; | |
673 | } | |
674 | ||
675 | EXPORT_SYMBOL(seq_list_start); | |
676 | ||
677 | struct list_head *seq_list_start_head(struct list_head *head, loff_t pos) | |
678 | { | |
679 | if (!pos) | |
680 | return head; | |
681 | ||
682 | return seq_list_start(head, pos - 1); | |
683 | } | |
684 | ||
685 | EXPORT_SYMBOL(seq_list_start_head); | |
686 | ||
687 | struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos) | |
688 | { | |
689 | struct list_head *lh; | |
690 | ||
691 | lh = ((struct list_head *)v)->next; | |
692 | ++*ppos; | |
693 | return lh == head ? NULL : lh; | |
694 | } | |
695 | ||
696 | EXPORT_SYMBOL(seq_list_next); |