projects/linux·blob v4.3 · refs

1020 lines · 22.5 KiB

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/export.h>
10#include <linux/seq_file.h>
11#include <linux/vmalloc.h>
12#include <linux/slab.h>
13#include <linux/cred.h>
14#include <linux/mm.h>
15#include <linux/printk.h>
16
17#include <asm/uaccess.h>
18#include <asm/page.h>
19
20static void seq_set_overflow(struct seq_file *m)
21{
22 m->count = m->size;
23}
24
25static void *seq_buf_alloc(unsigned long size)
26{
27 void *buf;
28
29 /*
30 * __GFP_NORETRY to avoid oom-killings with high-order allocations -
31 * it's better to fall back to vmalloc() than to kill things.
32 */
33 buf = kmalloc(size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
34 if (!buf && size > PAGE_SIZE)
35 buf = vmalloc(size);
36 return buf;
37}
38
39/**
40 * seq_open - initialize sequential file
41 * @file: file we initialize
42 * @op: method table describing the sequence
43 *
44 * seq_open() sets @file, associating it with a sequence described
45 * by @op. @op->start() sets the iterator up and returns the first
46 * element of sequence. @op->stop() shuts it down. @op->next()
47 * returns the next element of sequence. @op->show() prints element
48 * into the buffer. In case of error ->start() and ->next() return
49 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
50 * returns 0 in case of success and negative number in case of error.
51 * Returning SEQ_SKIP means "discard this element and move on".
52 * Note: seq_open() will allocate a struct seq_file and store its
53 * pointer in @file->private_data. This pointer should not be modified.
54 */
55int seq_open(struct file *file, const struct seq_operations *op)
56{
57 struct seq_file *p;
58
59 WARN_ON(file->private_data);
60
61 p = kzalloc(sizeof(*p), GFP_KERNEL);
62 if (!p)
63 return -ENOMEM;
64
65 file->private_data = p;
66
67 mutex_init(&p->lock);
68 p->op = op;
69#ifdef CONFIG_USER_NS
70 p->user_ns = file->f_cred->user_ns;
71#endif
72
73 /*
74 * Wrappers around seq_open(e.g. swaps_open) need to be
75 * aware of this. If they set f_version themselves, they
76 * should call seq_open first and then set f_version.
77 */
78 file->f_version = 0;
79
80 /*
81 * seq_files support lseek() and pread(). They do not implement
82 * write() at all, but we clear FMODE_PWRITE here for historical
83 * reasons.
84 *
85 * If a client of seq_files a) implements file.write() and b) wishes to
86 * support pwrite() then that client will need to implement its own
87 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
88 */
89 file->f_mode &= ~FMODE_PWRITE;
90 return 0;
91}
92EXPORT_SYMBOL(seq_open);
93
94static int traverse(struct seq_file *m, loff_t offset)
95{
96 loff_t pos = 0, index;
97 int error = 0;
98 void *p;
99
100 m->version = 0;
101 index = 0;
102 m->count = m->from = 0;
103 if (!offset) {
104 m->index = index;
105 return 0;
106 }
107 if (!m->buf) {
108 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
109 if (!m->buf)
110 return -ENOMEM;
111 }
112 p = m->op->start(m, &index);
113 while (p) {
114 error = PTR_ERR(p);
115 if (IS_ERR(p))
116 break;
117 error = m->op->show(m, p);
118 if (error < 0)
119 break;
120 if (unlikely(error)) {
121 error = 0;
122 m->count = 0;
123 }
124 if (seq_has_overflowed(m))
125 goto Eoverflow;
126 if (pos + m->count > offset) {
127 m->from = offset - pos;
128 m->count -= m->from;
129 m->index = index;
130 break;
131 }
132 pos += m->count;
133 m->count = 0;
134 if (pos == offset) {
135 index++;
136 m->index = index;
137 break;
138 }
139 p = m->op->next(m, p, &index);
140 }
141 m->op->stop(m, p);
142 m->index = index;
143 return error;
144
145Eoverflow:
146 m->op->stop(m, p);
147 kvfree(m->buf);
148 m->count = 0;
149 m->buf = seq_buf_alloc(m->size <<= 1);
150 return !m->buf ? -ENOMEM : -EAGAIN;
151}
152
153/**
154 * seq_read - ->read() method for sequential files.
155 * @file: the file to read from
156 * @buf: the buffer to read to
157 * @size: the maximum number of bytes to read
158 * @ppos: the current position in the file
159 *
160 * Ready-made ->f_op->read()
161 */
162ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
163{
164 struct seq_file *m = file->private_data;
165 size_t copied = 0;
166 loff_t pos;
167 size_t n;
168 void *p;
169 int err = 0;
170
171 mutex_lock(&m->lock);
172
173 /*
174 * seq_file->op->..m_start/m_stop/m_next may do special actions
175 * or optimisations based on the file->f_version, so we want to
176 * pass the file->f_version to those methods.
177 *
178 * seq_file->version is just copy of f_version, and seq_file
179 * methods can treat it simply as file version.
180 * It is copied in first and copied out after all operations.
181 * It is convenient to have it as part of structure to avoid the
182 * need of passing another argument to all the seq_file methods.
183 */
184 m->version = file->f_version;
185
186 /* Don't assume *ppos is where we left it */
187 if (unlikely(*ppos != m->read_pos)) {
188 while ((err = traverse(m, *ppos)) == -EAGAIN)
189 ;
190 if (err) {
191 /* With prejudice... */
192 m->read_pos = 0;
193 m->version = 0;
194 m->index = 0;
195 m->count = 0;
196 goto Done;
197 } else {
198 m->read_pos = *ppos;
199 }
200 }
201
202 /* grab buffer if we didn't have one */
203 if (!m->buf) {
204 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
205 if (!m->buf)
206 goto Enomem;
207 }
208 /* if not empty - flush it first */
209 if (m->count) {
210 n = min(m->count, size);
211 err = copy_to_user(buf, m->buf + m->from, n);
212 if (err)
213 goto Efault;
214 m->count -= n;
215 m->from += n;
216 size -= n;
217 buf += n;
218 copied += n;
219 if (!m->count)
220 m->index++;
221 if (!size)
222 goto Done;
223 }
224 /* we need at least one record in buffer */
225 pos = m->index;
226 p = m->op->start(m, &pos);
227 while (1) {
228 err = PTR_ERR(p);
229 if (!p || IS_ERR(p))
230 break;
231 err = m->op->show(m, p);
232 if (err < 0)
233 break;
234 if (unlikely(err))
235 m->count = 0;
236 if (unlikely(!m->count)) {
237 p = m->op->next(m, p, &pos);
238 m->index = pos;
239 continue;
240 }
241 if (m->count < m->size)
242 goto Fill;
243 m->op->stop(m, p);
244 kvfree(m->buf);
245 m->count = 0;
246 m->buf = seq_buf_alloc(m->size <<= 1);
247 if (!m->buf)
248 goto Enomem;
249 m->version = 0;
250 pos = m->index;
251 p = m->op->start(m, &pos);
252 }
253 m->op->stop(m, p);
254 m->count = 0;
255 goto Done;
256Fill:
257 /* they want more? let's try to get some more */
258 while (m->count < size) {
259 size_t offs = m->count;
260 loff_t next = pos;
261 p = m->op->next(m, p, &next);
262 if (!p || IS_ERR(p)) {
263 err = PTR_ERR(p);
264 break;
265 }
266 err = m->op->show(m, p);
267 if (seq_has_overflowed(m) || err) {
268 m->count = offs;
269 if (likely(err <= 0))
270 break;
271 }
272 pos = next;
273 }
274 m->op->stop(m, p);
275 n = min(m->count, size);
276 err = copy_to_user(buf, m->buf, n);
277 if (err)
278 goto Efault;
279 copied += n;
280 m->count -= n;
281 if (m->count)
282 m->from = n;
283 else
284 pos++;
285 m->index = pos;
286Done:
287 if (!copied)
288 copied = err;
289 else {
290 *ppos += copied;
291 m->read_pos += copied;
292 }
293 file->f_version = m->version;
294 mutex_unlock(&m->lock);
295 return copied;
296Enomem:
297 err = -ENOMEM;
298 goto Done;
299Efault:
300 err = -EFAULT;
301 goto Done;
302}
303EXPORT_SYMBOL(seq_read);
304
305/**
306 * seq_lseek - ->llseek() method for sequential files.
307 * @file: the file in question
308 * @offset: new position
309 * @whence: 0 for absolute, 1 for relative position
310 *
311 * Ready-made ->f_op->llseek()
312 */
313loff_t seq_lseek(struct file *file, loff_t offset, int whence)
314{
315 struct seq_file *m = file->private_data;
316 loff_t retval = -EINVAL;
317
318 mutex_lock(&m->lock);
319 m->version = file->f_version;
320 switch (whence) {
321 case SEEK_CUR:
322 offset += file->f_pos;
323 case SEEK_SET:
324 if (offset < 0)
325 break;
326 retval = offset;
327 if (offset != m->read_pos) {
328 while ((retval = traverse(m, offset)) == -EAGAIN)
329 ;
330 if (retval) {
331 /* with extreme prejudice... */
332 file->f_pos = 0;
333 m->read_pos = 0;
334 m->version = 0;
335 m->index = 0;
336 m->count = 0;
337 } else {
338 m->read_pos = offset;
339 retval = file->f_pos = offset;
340 }
341 } else {
342 file->f_pos = offset;
343 }
344 }
345 file->f_version = m->version;
346 mutex_unlock(&m->lock);
347 return retval;
348}
349EXPORT_SYMBOL(seq_lseek);
350
351/**
352 * seq_release - free the structures associated with sequential file.
353 * @file: file in question
354 * @inode: its inode
355 *
356 * Frees the structures associated with sequential file; can be used
357 * as ->f_op->release() if you don't have private data to destroy.
358 */
359int seq_release(struct inode *inode, struct file *file)
360{
361 struct seq_file *m = file->private_data;
362 kvfree(m->buf);
363 kfree(m);
364 return 0;
365}
366EXPORT_SYMBOL(seq_release);
367
368/**
369 * seq_escape - print string into buffer, escaping some characters
370 * @m: target buffer
371 * @s: string
372 * @esc: set of characters that need escaping
373 *
374 * Puts string into buffer, replacing each occurrence of character from
375 * @esc with usual octal escape.
376 * Use seq_has_overflowed() to check for errors.
377 */
378void seq_escape(struct seq_file *m, const char *s, const char *esc)
379{
380 char *end = m->buf + m->size;
381 char *p;
382 char c;
383
384 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
385 if (!strchr(esc, c)) {
386 *p++ = c;
387 continue;
388 }
389 if (p + 3 < end) {
390 *p++ = '\\';
391 *p++ = '0' + ((c & 0300) >> 6);
392 *p++ = '0' + ((c & 070) >> 3);
393 *p++ = '0' + (c & 07);
394 continue;
395 }
396 seq_set_overflow(m);
397 return;
398 }
399 m->count = p - m->buf;
400}
401EXPORT_SYMBOL(seq_escape);
402
403void seq_vprintf(struct seq_file *m, const char *f, va_list args)
404{
405 int len;
406
407 if (m->count < m->size) {
408 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
409 if (m->count + len < m->size) {
410 m->count += len;
411 return;
412 }
413 }
414 seq_set_overflow(m);
415}
416EXPORT_SYMBOL(seq_vprintf);
417
418void seq_printf(struct seq_file *m, const char *f, ...)
419{
420 va_list args;
421
422 va_start(args, f);
423 seq_vprintf(m, f, args);
424 va_end(args);
425}
426EXPORT_SYMBOL(seq_printf);
427
428/**
429 * mangle_path - mangle and copy path to buffer beginning
430 * @s: buffer start
431 * @p: beginning of path in above buffer
432 * @esc: set of characters that need escaping
433 *
434 * Copy the path from @p to @s, replacing each occurrence of character from
435 * @esc with usual octal escape.
436 * Returns pointer past last written character in @s, or NULL in case of
437 * failure.
438 */
439char *mangle_path(char *s, const char *p, const char *esc)
440{
441 while (s <= p) {
442 char c = *p++;
443 if (!c) {
444 return s;
445 } else if (!strchr(esc, c)) {
446 *s++ = c;
447 } else if (s + 4 > p) {
448 break;
449 } else {
450 *s++ = '\\';
451 *s++ = '0' + ((c & 0300) >> 6);
452 *s++ = '0' + ((c & 070) >> 3);
453 *s++ = '0' + (c & 07);
454 }
455 }
456 return NULL;
457}
458EXPORT_SYMBOL(mangle_path);
459
460/**
461 * seq_path - seq_file interface to print a pathname
462 * @m: the seq_file handle
463 * @path: the struct path to print
464 * @esc: set of characters to escape in the output
465 *
466 * return the absolute path of 'path', as represented by the
467 * dentry / mnt pair in the path parameter.
468 */
469int seq_path(struct seq_file *m, const struct path *path, const char *esc)
470{
471 char *buf;
472 size_t size = seq_get_buf(m, &buf);
473 int res = -1;
474
475 if (size) {
476 char *p = d_path(path, buf, size);
477 if (!IS_ERR(p)) {
478 char *end = mangle_path(buf, p, esc);
479 if (end)
480 res = end - buf;
481 }
482 }
483 seq_commit(m, res);
484
485 return res;
486}
487EXPORT_SYMBOL(seq_path);
488
489/**
490 * seq_file_path - seq_file interface to print a pathname of a file
491 * @m: the seq_file handle
492 * @file: the struct file to print
493 * @esc: set of characters to escape in the output
494 *
495 * return the absolute path to the file.
496 */
497int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
498{
499 return seq_path(m, &file->f_path, esc);
500}
501EXPORT_SYMBOL(seq_file_path);
502
503/*
504 * Same as seq_path, but relative to supplied root.
505 */
506int seq_path_root(struct seq_file *m, const struct path *path,
507 const struct path *root, const char *esc)
508{
509 char *buf;
510 size_t size = seq_get_buf(m, &buf);
511 int res = -ENAMETOOLONG;
512
513 if (size) {
514 char *p;
515
516 p = __d_path(path, root, buf, size);
517 if (!p)
518 return SEQ_SKIP;
519 res = PTR_ERR(p);
520 if (!IS_ERR(p)) {
521 char *end = mangle_path(buf, p, esc);
522 if (end)
523 res = end - buf;
524 else
525 res = -ENAMETOOLONG;
526 }
527 }
528 seq_commit(m, res);
529
530 return res < 0 && res != -ENAMETOOLONG ? res : 0;
531}
532
533/*
534 * returns the path of the 'dentry' from the root of its filesystem.
535 */
536int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
537{
538 char *buf;
539 size_t size = seq_get_buf(m, &buf);
540 int res = -1;
541
542 if (size) {
543 char *p = dentry_path(dentry, buf, size);
544 if (!IS_ERR(p)) {
545 char *end = mangle_path(buf, p, esc);
546 if (end)
547 res = end - buf;
548 }
549 }
550 seq_commit(m, res);
551
552 return res;
553}
554EXPORT_SYMBOL(seq_dentry);
555
556static void *single_start(struct seq_file *p, loff_t *pos)
557{
558 return NULL + (*pos == 0);
559}
560
561static void *single_next(struct seq_file *p, void *v, loff_t *pos)
562{
563 ++*pos;
564 return NULL;
565}
566
567static void single_stop(struct seq_file *p, void *v)
568{
569}
570
571int single_open(struct file *file, int (*show)(struct seq_file *, void *),
572 void *data)
573{
574 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
575 int res = -ENOMEM;
576
577 if (op) {
578 op->start = single_start;
579 op->next = single_next;
580 op->stop = single_stop;
581 op->show = show;
582 res = seq_open(file, op);
583 if (!res)
584 ((struct seq_file *)file->private_data)->private = data;
585 else
586 kfree(op);
587 }
588 return res;
589}
590EXPORT_SYMBOL(single_open);
591
592int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
593 void *data, size_t size)
594{
595 char *buf = seq_buf_alloc(size);
596 int ret;
597 if (!buf)
598 return -ENOMEM;
599 ret = single_open(file, show, data);
600 if (ret) {
601 kvfree(buf);
602 return ret;
603 }
604 ((struct seq_file *)file->private_data)->buf = buf;
605 ((struct seq_file *)file->private_data)->size = size;
606 return 0;
607}
608EXPORT_SYMBOL(single_open_size);
609
610int single_release(struct inode *inode, struct file *file)
611{
612 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
613 int res = seq_release(inode, file);
614 kfree(op);
615 return res;
616}
617EXPORT_SYMBOL(single_release);
618
619int seq_release_private(struct inode *inode, struct file *file)
620{
621 struct seq_file *seq = file->private_data;
622
623 kfree(seq->private);
624 seq->private = NULL;
625 return seq_release(inode, file);
626}
627EXPORT_SYMBOL(seq_release_private);
628
629void *__seq_open_private(struct file *f, const struct seq_operations *ops,
630 int psize)
631{
632 int rc;
633 void *private;
634 struct seq_file *seq;
635
636 private = kzalloc(psize, GFP_KERNEL);
637 if (private == NULL)
638 goto out;
639
640 rc = seq_open(f, ops);
641 if (rc < 0)
642 goto out_free;
643
644 seq = f->private_data;
645 seq->private = private;
646 return private;
647
648out_free:
649 kfree(private);
650out:
651 return NULL;
652}
653EXPORT_SYMBOL(__seq_open_private);
654
655int seq_open_private(struct file *filp, const struct seq_operations *ops,
656 int psize)
657{
658 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
659}
660EXPORT_SYMBOL(seq_open_private);
661
662void seq_putc(struct seq_file *m, char c)
663{
664 if (m->count >= m->size)
665 return;
666
667 m->buf[m->count++] = c;
668}
669EXPORT_SYMBOL(seq_putc);
670
671void seq_puts(struct seq_file *m, const char *s)
672{
673 int len = strlen(s);
674
675 if (m->count + len >= m->size) {
676 seq_set_overflow(m);
677 return;
678 }
679 memcpy(m->buf + m->count, s, len);
680 m->count += len;
681}
682EXPORT_SYMBOL(seq_puts);
683
684/*
685 * A helper routine for putting decimal numbers without rich format of printf().
686 * only 'unsigned long long' is supported.
687 * This routine will put one byte delimiter + number into seq_file.
688 * This routine is very quick when you show lots of numbers.
689 * In usual cases, it will be better to use seq_printf(). It's easier to read.
690 */
691void seq_put_decimal_ull(struct seq_file *m, char delimiter,
692 unsigned long long num)
693{
694 int len;
695
696 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
697 goto overflow;
698
699 if (delimiter)
700 m->buf[m->count++] = delimiter;
701
702 if (num < 10) {
703 m->buf[m->count++] = num + '0';
704 return;
705 }
706
707 len = num_to_str(m->buf + m->count, m->size - m->count, num);
708 if (!len)
709 goto overflow;
710 m->count += len;
711 return;
712
713overflow:
714 seq_set_overflow(m);
715}
716EXPORT_SYMBOL(seq_put_decimal_ull);
717
718void seq_put_decimal_ll(struct seq_file *m, char delimiter, long long num)
719{
720 if (num < 0) {
721 if (m->count + 3 >= m->size) {
722 seq_set_overflow(m);
723 return;
724 }
725 if (delimiter)
726 m->buf[m->count++] = delimiter;
727 num = -num;
728 delimiter = '-';
729 }
730 seq_put_decimal_ull(m, delimiter, num);
731}
732EXPORT_SYMBOL(seq_put_decimal_ll);
733
734/**
735 * seq_write - write arbitrary data to buffer
736 * @seq: seq_file identifying the buffer to which data should be written
737 * @data: data address
738 * @len: number of bytes
739 *
740 * Return 0 on success, non-zero otherwise.
741 */
742int seq_write(struct seq_file *seq, const void *data, size_t len)
743{
744 if (seq->count + len < seq->size) {
745 memcpy(seq->buf + seq->count, data, len);
746 seq->count += len;
747 return 0;
748 }
749 seq_set_overflow(seq);
750 return -1;
751}
752EXPORT_SYMBOL(seq_write);
753
754/**
755 * seq_pad - write padding spaces to buffer
756 * @m: seq_file identifying the buffer to which data should be written
757 * @c: the byte to append after padding if non-zero
758 */
759void seq_pad(struct seq_file *m, char c)
760{
761 int size = m->pad_until - m->count;
762 if (size > 0)
763 seq_printf(m, "%*s", size, "");
764 if (c)
765 seq_putc(m, c);
766}
767EXPORT_SYMBOL(seq_pad);
768
769/* A complete analogue of print_hex_dump() */
770void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
771 int rowsize, int groupsize, const void *buf, size_t len,
772 bool ascii)
773{
774 const u8 *ptr = buf;
775 int i, linelen, remaining = len;
776 int ret;
777
778 if (rowsize != 16 && rowsize != 32)
779 rowsize = 16;
780
781 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
782 linelen = min(remaining, rowsize);
783 remaining -= rowsize;
784
785 switch (prefix_type) {
786 case DUMP_PREFIX_ADDRESS:
787 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
788 break;
789 case DUMP_PREFIX_OFFSET:
790 seq_printf(m, "%s%.8x: ", prefix_str, i);
791 break;
792 default:
793 seq_printf(m, "%s", prefix_str);
794 break;
795 }
796
797 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
798 m->buf + m->count, m->size - m->count,
799 ascii);
800 if (ret >= m->size - m->count) {
801 seq_set_overflow(m);
802 } else {
803 m->count += ret;
804 seq_putc(m, '\n');
805 }
806 }
807}
808EXPORT_SYMBOL(seq_hex_dump);
809
810struct list_head *seq_list_start(struct list_head *head, loff_t pos)
811{
812 struct list_head *lh;
813
814 list_for_each(lh, head)
815 if (pos-- == 0)
816 return lh;
817
818 return NULL;
819}
820EXPORT_SYMBOL(seq_list_start);
821
822struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
823{
824 if (!pos)
825 return head;
826
827 return seq_list_start(head, pos - 1);
828}
829EXPORT_SYMBOL(seq_list_start_head);
830
831struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
832{
833 struct list_head *lh;
834
835 lh = ((struct list_head *)v)->next;
836 ++*ppos;
837 return lh == head ? NULL : lh;
838}
839EXPORT_SYMBOL(seq_list_next);
840
841/**
842 * seq_hlist_start - start an iteration of a hlist
843 * @head: the head of the hlist
844 * @pos: the start position of the sequence
845 *
846 * Called at seq_file->op->start().
847 */
848struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
849{
850 struct hlist_node *node;
851
852 hlist_for_each(node, head)
853 if (pos-- == 0)
854 return node;
855 return NULL;
856}
857EXPORT_SYMBOL(seq_hlist_start);
858
859/**
860 * seq_hlist_start_head - start an iteration of a hlist
861 * @head: the head of the hlist
862 * @pos: the start position of the sequence
863 *
864 * Called at seq_file->op->start(). Call this function if you want to
865 * print a header at the top of the output.
866 */
867struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
868{
869 if (!pos)
870 return SEQ_START_TOKEN;
871
872 return seq_hlist_start(head, pos - 1);
873}
874EXPORT_SYMBOL(seq_hlist_start_head);
875
876/**
877 * seq_hlist_next - move to the next position of the hlist
878 * @v: the current iterator
879 * @head: the head of the hlist
880 * @ppos: the current position
881 *
882 * Called at seq_file->op->next().
883 */
884struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
885 loff_t *ppos)
886{
887 struct hlist_node *node = v;
888
889 ++*ppos;
890 if (v == SEQ_START_TOKEN)
891 return head->first;
892 else
893 return node->next;
894}
895EXPORT_SYMBOL(seq_hlist_next);
896
897/**
898 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
899 * @head: the head of the hlist
900 * @pos: the start position of the sequence
901 *
902 * Called at seq_file->op->start().
903 *
904 * This list-traversal primitive may safely run concurrently with
905 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
906 * as long as the traversal is guarded by rcu_read_lock().
907 */
908struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
909 loff_t pos)
910{
911 struct hlist_node *node;
912
913 __hlist_for_each_rcu(node, head)
914 if (pos-- == 0)
915 return node;
916 return NULL;
917}
918EXPORT_SYMBOL(seq_hlist_start_rcu);
919
920/**
921 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
922 * @head: the head of the hlist
923 * @pos: the start position of the sequence
924 *
925 * Called at seq_file->op->start(). Call this function if you want to
926 * print a header at the top of the output.
927 *
928 * This list-traversal primitive may safely run concurrently with
929 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
930 * as long as the traversal is guarded by rcu_read_lock().
931 */
932struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
933 loff_t pos)
934{
935 if (!pos)
936 return SEQ_START_TOKEN;
937
938 return seq_hlist_start_rcu(head, pos - 1);
939}
940EXPORT_SYMBOL(seq_hlist_start_head_rcu);
941
942/**
943 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
944 * @v: the current iterator
945 * @head: the head of the hlist
946 * @ppos: the current position
947 *
948 * Called at seq_file->op->next().
949 *
950 * This list-traversal primitive may safely run concurrently with
951 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
952 * as long as the traversal is guarded by rcu_read_lock().
953 */
954struct hlist_node *seq_hlist_next_rcu(void *v,
955 struct hlist_head *head,
956 loff_t *ppos)
957{
958 struct hlist_node *node = v;
959
960 ++*ppos;
961 if (v == SEQ_START_TOKEN)
962 return rcu_dereference(head->first);
963 else
964 return rcu_dereference(node->next);
965}
966EXPORT_SYMBOL(seq_hlist_next_rcu);
967
968/**
969 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
970 * @head: pointer to percpu array of struct hlist_heads
971 * @cpu: pointer to cpu "cursor"
972 * @pos: start position of sequence
973 *
974 * Called at seq_file->op->start().
975 */
976struct hlist_node *
977seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
978{
979 struct hlist_node *node;
980
981 for_each_possible_cpu(*cpu) {
982 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
983 if (pos-- == 0)
984 return node;
985 }
986 }
987 return NULL;
988}
989EXPORT_SYMBOL(seq_hlist_start_percpu);
990
991/**
992 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
993 * @v: pointer to current hlist_node
994 * @head: pointer to percpu array of struct hlist_heads
995 * @cpu: pointer to cpu "cursor"
996 * @pos: start position of sequence
997 *
998 * Called at seq_file->op->next().
999 */
1000struct hlist_node *
1001seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1002 int *cpu, loff_t *pos)
1003{
1004 struct hlist_node *node = v;
1005
1006 ++*pos;
1007
1008 if (node->next)
1009 return node->next;
1010
1011 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1012 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1013 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1014
1015 if (!hlist_empty(bucket))
1016 return bucket->first;
1017 }
1018 return NULL;
1019}
1020EXPORT_SYMBOL(seq_hlist_next_percpu);