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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/seq_file.c
4 *
5 * helper functions for making synthetic files from sequences of records.
6 * initial implementation -- AV, Oct 2001.
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/cache.h>
12#include <linux/fs.h>
13#include <linux/export.h>
14#include <linux/hex.h>
15#include <linux/seq_file.h>
16#include <linux/vmalloc.h>
17#include <linux/slab.h>
18#include <linux/cred.h>
19#include <linux/mm.h>
20#include <linux/printk.h>
21#include <linux/string_helpers.h>
22#include <linux/uio.h>
23
24#include <linux/uaccess.h>
25#include <asm/page.h>
26
27static struct kmem_cache *seq_file_cache __ro_after_init;
28
29static void seq_set_overflow(struct seq_file *m)
30{
31 m->count = m->size;
32}
33
34static void *seq_buf_alloc(unsigned long size)
35{
36 if (unlikely(size > MAX_RW_COUNT))
37 return NULL;
38
39 return kvmalloc(size, GFP_KERNEL_ACCOUNT);
40}
41
42/**
43 * seq_open - initialize sequential file
44 * @file: file we initialize
45 * @op: method table describing the sequence
46 *
47 * seq_open() sets @file, associating it with a sequence described
48 * by @op. @op->start() sets the iterator up and returns the first
49 * element of sequence. @op->stop() shuts it down. @op->next()
50 * returns the next element of sequence. @op->show() prints element
51 * into the buffer. In case of error ->start() and ->next() return
52 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
53 * returns 0 in case of success and negative number in case of error.
54 * Returning SEQ_SKIP means "discard this element and move on".
55 * Note: seq_open() will allocate a struct seq_file and store its
56 * pointer in @file->private_data. This pointer should not be modified.
57 */
58int seq_open(struct file *file, const struct seq_operations *op)
59{
60 struct seq_file *p;
61
62 WARN_ON(file->private_data);
63
64 p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL);
65 if (!p)
66 return -ENOMEM;
67
68 file->private_data = p;
69
70 mutex_init(&p->lock);
71 p->op = op;
72
73 // No refcounting: the lifetime of 'p' is constrained
74 // to the lifetime of the file.
75 p->file = file;
76
77 /*
78 * seq_files support lseek() and pread(). They do not implement
79 * write() at all, but we clear FMODE_PWRITE here for historical
80 * reasons.
81 *
82 * If a client of seq_files a) implements file.write() and b) wishes to
83 * support pwrite() then that client will need to implement its own
84 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
85 */
86 file->f_mode &= ~FMODE_PWRITE;
87 return 0;
88}
89EXPORT_SYMBOL(seq_open);
90
91static int traverse(struct seq_file *m, loff_t offset)
92{
93 loff_t pos = 0;
94 int error = 0;
95 void *p;
96
97 m->index = 0;
98 m->count = m->from = 0;
99 if (!offset)
100 return 0;
101
102 if (!m->buf) {
103 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
104 if (!m->buf)
105 return -ENOMEM;
106 }
107 p = m->op->start(m, &m->index);
108 while (p) {
109 error = PTR_ERR(p);
110 if (IS_ERR(p))
111 break;
112 error = m->op->show(m, p);
113 if (error < 0)
114 break;
115 if (unlikely(error)) {
116 error = 0;
117 m->count = 0;
118 }
119 if (seq_has_overflowed(m))
120 goto Eoverflow;
121 p = m->op->next(m, p, &m->index);
122 if (pos + m->count > offset) {
123 m->from = offset - pos;
124 m->count -= m->from;
125 break;
126 }
127 pos += m->count;
128 m->count = 0;
129 if (pos == offset)
130 break;
131 }
132 m->op->stop(m, p);
133 return error;
134
135Eoverflow:
136 m->op->stop(m, p);
137 kvfree(m->buf);
138 m->count = 0;
139 m->buf = seq_buf_alloc(m->size <<= 1);
140 return !m->buf ? -ENOMEM : -EAGAIN;
141}
142
143/**
144 * seq_read - ->read() method for sequential files.
145 * @file: the file to read from
146 * @buf: the buffer to read to
147 * @size: the maximum number of bytes to read
148 * @ppos: the current position in the file
149 *
150 * Ready-made ->f_op->read()
151 */
152ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
153{
154 struct iovec iov = { .iov_base = buf, .iov_len = size};
155 struct kiocb kiocb;
156 struct iov_iter iter;
157 ssize_t ret;
158
159 init_sync_kiocb(&kiocb, file);
160 iov_iter_init(&iter, ITER_DEST, &iov, 1, size);
161
162 kiocb.ki_pos = *ppos;
163 ret = seq_read_iter(&kiocb, &iter);
164 *ppos = kiocb.ki_pos;
165 return ret;
166}
167EXPORT_SYMBOL(seq_read);
168
169/*
170 * Ready-made ->f_op->read_iter()
171 */
172ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)
173{
174 struct seq_file *m = iocb->ki_filp->private_data;
175 size_t copied = 0;
176 size_t n;
177 void *p;
178 int err = 0;
179
180 if (!iov_iter_count(iter))
181 return 0;
182
183 mutex_lock(&m->lock);
184
185 /*
186 * if request is to read from zero offset, reset iterator to first
187 * record as it might have been already advanced by previous requests
188 */
189 if (iocb->ki_pos == 0) {
190 m->index = 0;
191 m->count = 0;
192 }
193
194 /* Don't assume ki_pos is where we left it */
195 if (unlikely(iocb->ki_pos != m->read_pos)) {
196 while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN)
197 ;
198 if (err) {
199 /* With prejudice... */
200 m->read_pos = 0;
201 m->index = 0;
202 m->count = 0;
203 goto Done;
204 } else {
205 m->read_pos = iocb->ki_pos;
206 }
207 }
208
209 /* grab buffer if we didn't have one */
210 if (!m->buf) {
211 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
212 if (!m->buf)
213 goto Enomem;
214 }
215 // something left in the buffer - copy it out first
216 if (m->count) {
217 n = copy_to_iter(m->buf + m->from, m->count, iter);
218 m->count -= n;
219 m->from += n;
220 copied += n;
221 if (m->count) // hadn't managed to copy everything
222 goto Done;
223 }
224 // get a non-empty record in the buffer
225 m->from = 0;
226 p = m->op->start(m, &m->index);
227 while (1) {
228 err = PTR_ERR(p);
229 if (!p || IS_ERR(p)) // EOF or an error
230 break;
231 err = m->op->show(m, p);
232 if (err < 0) // hard error
233 break;
234 if (unlikely(err)) // ->show() says "skip it"
235 m->count = 0;
236 if (unlikely(!m->count)) { // empty record
237 p = m->op->next(m, p, &m->index);
238 continue;
239 }
240 if (!seq_has_overflowed(m)) // got it
241 goto Fill;
242 // need a bigger buffer
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 p = m->op->start(m, &m->index);
250 }
251 // EOF or an error
252 m->op->stop(m, p);
253 m->count = 0;
254 goto Done;
255Fill:
256 // one non-empty record is in the buffer; if they want more,
257 // try to fit more in, but in any case we need to advance
258 // the iterator once for every record shown.
259 while (1) {
260 size_t offs = m->count;
261 loff_t pos = m->index;
262
263 p = m->op->next(m, p, &m->index);
264 if (pos == m->index) {
265 pr_info_ratelimited("buggy .next function %ps did not update position index\n",
266 m->op->next);
267 m->index++;
268 }
269 if (!p || IS_ERR(p)) // no next record for us
270 break;
271 if (m->count >= iov_iter_count(iter))
272 break;
273 err = m->op->show(m, p);
274 if (err > 0) { // ->show() says "skip it"
275 m->count = offs;
276 } else if (err || seq_has_overflowed(m)) {
277 m->count = offs;
278 break;
279 }
280 }
281 m->op->stop(m, p);
282 n = copy_to_iter(m->buf, m->count, iter);
283 copied += n;
284 m->count -= n;
285 m->from = n;
286Done:
287 if (unlikely(!copied)) {
288 copied = m->count ? -EFAULT : err;
289 } else {
290 iocb->ki_pos += copied;
291 m->read_pos += copied;
292 }
293 mutex_unlock(&m->lock);
294 return copied;
295Enomem:
296 err = -ENOMEM;
297 goto Done;
298}
299EXPORT_SYMBOL(seq_read_iter);
300
301/**
302 * seq_lseek - ->llseek() method for sequential files.
303 * @file: the file in question
304 * @offset: new position
305 * @whence: 0 for absolute, 1 for relative position
306 *
307 * Ready-made ->f_op->llseek()
308 */
309loff_t seq_lseek(struct file *file, loff_t offset, int whence)
310{
311 struct seq_file *m = file->private_data;
312 loff_t retval = -EINVAL;
313
314 mutex_lock(&m->lock);
315 switch (whence) {
316 case SEEK_CUR:
317 offset += file->f_pos;
318 fallthrough;
319 case SEEK_SET:
320 if (offset < 0)
321 break;
322 retval = offset;
323 if (offset != m->read_pos) {
324 while ((retval = traverse(m, offset)) == -EAGAIN)
325 ;
326 if (retval) {
327 /* with extreme prejudice... */
328 file->f_pos = 0;
329 m->read_pos = 0;
330 m->index = 0;
331 m->count = 0;
332 } else {
333 m->read_pos = offset;
334 retval = file->f_pos = offset;
335 }
336 } else {
337 file->f_pos = offset;
338 }
339 }
340 mutex_unlock(&m->lock);
341 return retval;
342}
343EXPORT_SYMBOL(seq_lseek);
344
345/**
346 * seq_release - free the structures associated with sequential file.
347 * @inode: its inode
348 * @file: file in question
349 *
350 * Frees the structures associated with sequential file; can be used
351 * as ->f_op->release() if you don't have private data to destroy.
352 */
353int seq_release(struct inode *inode, struct file *file)
354{
355 struct seq_file *m = file->private_data;
356 kvfree(m->buf);
357 kmem_cache_free(seq_file_cache, m);
358 return 0;
359}
360EXPORT_SYMBOL(seq_release);
361
362/**
363 * seq_escape_mem - print data into buffer, escaping some characters
364 * @m: target buffer
365 * @src: source buffer
366 * @len: size of source buffer
367 * @flags: flags to pass to string_escape_mem()
368 * @esc: set of characters that need escaping
369 *
370 * Puts data into buffer, replacing each occurrence of character from
371 * given class (defined by @flags and @esc) with printable escaped sequence.
372 *
373 * Use seq_has_overflowed() to check for errors.
374 */
375void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
376 unsigned int flags, const char *esc)
377{
378 char *buf;
379 size_t size = seq_get_buf(m, &buf);
380 int ret;
381
382 ret = string_escape_mem(src, len, buf, size, flags, esc);
383 seq_commit(m, ret < size ? ret : -1);
384}
385EXPORT_SYMBOL(seq_escape_mem);
386
387void seq_vprintf(struct seq_file *m, const char *f, va_list args)
388{
389 int len;
390
391 if (m->count < m->size) {
392 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
393 if (m->count + len < m->size) {
394 m->count += len;
395 return;
396 }
397 }
398 seq_set_overflow(m);
399}
400EXPORT_SYMBOL(seq_vprintf);
401
402void seq_printf(struct seq_file *m, const char *f, ...)
403{
404 va_list args;
405
406 va_start(args, f);
407 seq_vprintf(m, f, args);
408 va_end(args);
409}
410EXPORT_SYMBOL(seq_printf);
411
412#ifdef CONFIG_BINARY_PRINTF
413void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
414{
415 int len;
416
417 if (m->count < m->size) {
418 len = bstr_printf(m->buf + m->count, m->size - m->count, f,
419 binary);
420 if (m->count + len < m->size) {
421 m->count += len;
422 return;
423 }
424 }
425 seq_set_overflow(m);
426}
427EXPORT_SYMBOL(seq_bprintf);
428#endif /* CONFIG_BINARY_PRINTF */
429
430/**
431 * seq_mangle_path - mangle and copy path to buffer beginning
432 * @s: buffer start
433 * @p: beginning of path in above buffer
434 * @esc: set of characters that need escaping
435 *
436 * Copy the path from @p to @s, replacing each occurrence of character from
437 * @esc with usual octal escape.
438 * Returns pointer past last written character in @s, or NULL in case of
439 * failure.
440 */
441char *seq_mangle_path(char *s, const char *p, const char *esc)
442{
443 while (s <= p) {
444 char c = *p++;
445 if (!c) {
446 return s;
447 } else if (!strchr(esc, c)) {
448 *s++ = c;
449 } else if (s + 4 > p) {
450 break;
451 } else {
452 *s++ = '\\';
453 *s++ = '0' + ((c & 0300) >> 6);
454 *s++ = '0' + ((c & 070) >> 3);
455 *s++ = '0' + (c & 07);
456 }
457 }
458 return NULL;
459}
460
461/**
462 * seq_path - seq_file interface to print a pathname
463 * @m: the seq_file handle
464 * @path: the struct path to print
465 * @esc: set of characters to escape in the output
466 *
467 * return the absolute path of 'path', as represented by the
468 * dentry / mnt pair in the path parameter.
469 */
470int seq_path(struct seq_file *m, const struct path *path, const char *esc)
471{
472 char *buf;
473 size_t size = seq_get_buf(m, &buf);
474 int res = -1;
475
476 if (size) {
477 char *p = d_path(path, buf, size);
478 if (!IS_ERR(p)) {
479 char *end = seq_mangle_path(buf, p, esc);
480 if (end)
481 res = end - buf;
482 }
483 }
484 seq_commit(m, res);
485
486 return res;
487}
488EXPORT_SYMBOL(seq_path);
489
490/**
491 * seq_file_path - seq_file interface to print a pathname of a file
492 * @m: the seq_file handle
493 * @file: the struct file to print
494 * @esc: set of characters to escape in the output
495 *
496 * return the absolute path to the file.
497 */
498int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
499{
500 return seq_path(m, &file->f_path, esc);
501}
502EXPORT_SYMBOL(seq_file_path);
503
504/*
505 * Same as seq_path, but relative to supplied root.
506 */
507int seq_path_root(struct seq_file *m, const struct path *path,
508 const struct path *root, const char *esc)
509{
510 char *buf;
511 size_t size = seq_get_buf(m, &buf);
512 int res = -ENAMETOOLONG;
513
514 if (size) {
515 char *p;
516
517 p = __d_path(path, root, buf, size);
518 if (!p)
519 return SEQ_SKIP;
520 res = PTR_ERR(p);
521 if (!IS_ERR(p)) {
522 char *end = seq_mangle_path(buf, p, esc);
523 if (end)
524 res = end - buf;
525 else
526 res = -ENAMETOOLONG;
527 }
528 }
529 seq_commit(m, res);
530
531 return res < 0 && res != -ENAMETOOLONG ? res : 0;
532}
533
534/*
535 * returns the path of the 'dentry' from the root of its filesystem.
536 */
537int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
538{
539 char *buf;
540 size_t size = seq_get_buf(m, &buf);
541 int res = -1;
542
543 if (size) {
544 char *p = dentry_path(dentry, buf, size);
545 if (!IS_ERR(p)) {
546 char *end = seq_mangle_path(buf, p, esc);
547 if (end)
548 res = end - buf;
549 }
550 }
551 seq_commit(m, res);
552
553 return res;
554}
555EXPORT_SYMBOL(seq_dentry);
556
557void *single_start(struct seq_file *p, loff_t *pos)
558{
559 return *pos ? NULL : SEQ_START_TOKEN;
560}
561
562static void *single_next(struct seq_file *p, void *v, loff_t *pos)
563{
564 ++*pos;
565 return NULL;
566}
567
568static void single_stop(struct seq_file *p, void *v)
569{
570}
571
572int single_open(struct file *file, int (*show)(struct seq_file *, void *),
573 void *data)
574{
575 struct seq_operations *op = kmalloc_obj(*op, GFP_KERNEL_ACCOUNT);
576 int res = -ENOMEM;
577
578 if (op) {
579 op->start = single_start;
580 op->next = single_next;
581 op->stop = single_stop;
582 op->show = show;
583 res = seq_open(file, op);
584 if (!res)
585 ((struct seq_file *)file->private_data)->private = data;
586 else
587 kfree(op);
588 }
589 return res;
590}
591EXPORT_SYMBOL(single_open);
592
593int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
594 void *data, size_t size)
595{
596 char *buf = seq_buf_alloc(size);
597 int ret;
598 if (!buf)
599 return -ENOMEM;
600 ret = single_open(file, show, data);
601 if (ret) {
602 kvfree(buf);
603 return ret;
604 }
605 ((struct seq_file *)file->private_data)->buf = buf;
606 ((struct seq_file *)file->private_data)->size = size;
607 return 0;
608}
609EXPORT_SYMBOL(single_open_size);
610
611int single_release(struct inode *inode, struct file *file)
612{
613 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
614 int res = seq_release(inode, file);
615 kfree(op);
616 return res;
617}
618EXPORT_SYMBOL(single_release);
619
620int seq_release_private(struct inode *inode, struct file *file)
621{
622 struct seq_file *seq = file->private_data;
623
624 kfree(seq->private);
625 seq->private = NULL;
626 return seq_release(inode, file);
627}
628EXPORT_SYMBOL(seq_release_private);
629
630void *__seq_open_private(struct file *f, const struct seq_operations *ops,
631 int psize)
632{
633 int rc;
634 void *private;
635 struct seq_file *seq;
636
637 private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
638 if (private == NULL)
639 goto out;
640
641 rc = seq_open(f, ops);
642 if (rc < 0)
643 goto out_free;
644
645 seq = f->private_data;
646 seq->private = private;
647 return private;
648
649out_free:
650 kfree(private);
651out:
652 return NULL;
653}
654EXPORT_SYMBOL(__seq_open_private);
655
656int seq_open_private(struct file *filp, const struct seq_operations *ops,
657 int psize)
658{
659 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
660}
661EXPORT_SYMBOL(seq_open_private);
662
663void seq_putc(struct seq_file *m, char c)
664{
665 if (m->count >= m->size)
666 return;
667
668 m->buf[m->count++] = c;
669}
670EXPORT_SYMBOL(seq_putc);
671
672void __seq_puts(struct seq_file *m, const char *s)
673{
674 seq_write(m, s, strlen(s));
675}
676EXPORT_SYMBOL(__seq_puts);
677
678/**
679 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers
680 * without rich format of printf().
681 * only 'unsigned long long' is supported.
682 * @m: seq_file identifying the buffer to which data should be written
683 * @delimiter: a string which is printed before the number
684 * @num: the number
685 * @width: a minimum field width
686 *
687 * This routine will put strlen(delimiter) + number into seq_filed.
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_width(struct seq_file *m, const char *delimiter,
692 unsigned long long num, unsigned int width)
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 && delimiter[0]) {
700 if (delimiter[1] == 0)
701 seq_putc(m, delimiter[0]);
702 else
703 seq_puts(m, delimiter);
704 }
705
706 if (!width)
707 width = 1;
708
709 if (m->count + width >= m->size)
710 goto overflow;
711
712 len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
713 if (!len)
714 goto overflow;
715
716 m->count += len;
717 return;
718
719overflow:
720 seq_set_overflow(m);
721}
722
723void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
724 unsigned long long num)
725{
726 return seq_put_decimal_ull_width(m, delimiter, num, 0);
727}
728EXPORT_SYMBOL(seq_put_decimal_ull);
729
730/**
731 * seq_put_hex_ll - put a number in hexadecimal notation
732 * @m: seq_file identifying the buffer to which data should be written
733 * @delimiter: a string which is printed before the number
734 * @v: the number
735 * @width: a minimum field width
736 *
737 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
738 *
739 * This routine is very quick when you show lots of numbers.
740 * In usual cases, it will be better to use seq_printf(). It's easier to read.
741 */
742void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
743 unsigned long long v, unsigned int width)
744{
745 unsigned int len;
746 int i;
747
748 if (delimiter && delimiter[0]) {
749 if (delimiter[1] == 0)
750 seq_putc(m, delimiter[0]);
751 else
752 seq_puts(m, delimiter);
753 }
754
755 /* If x is 0, the result of __builtin_clzll is undefined */
756 if (v == 0)
757 len = 1;
758 else
759 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
760
761 if (len < width)
762 len = width;
763
764 if (m->count + len > m->size) {
765 seq_set_overflow(m);
766 return;
767 }
768
769 for (i = len - 1; i >= 0; i--) {
770 m->buf[m->count + i] = hex_asc[0xf & v];
771 v = v >> 4;
772 }
773 m->count += len;
774}
775
776void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
777{
778 int len;
779
780 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
781 goto overflow;
782
783 if (delimiter && delimiter[0]) {
784 if (delimiter[1] == 0)
785 seq_putc(m, delimiter[0]);
786 else
787 seq_puts(m, delimiter);
788 }
789
790 if (m->count + 2 >= m->size)
791 goto overflow;
792
793 if (num < 0) {
794 m->buf[m->count++] = '-';
795 num = -num;
796 }
797
798 if (num < 10) {
799 m->buf[m->count++] = num + '0';
800 return;
801 }
802
803 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
804 if (!len)
805 goto overflow;
806
807 m->count += len;
808 return;
809
810overflow:
811 seq_set_overflow(m);
812}
813EXPORT_SYMBOL(seq_put_decimal_ll);
814
815/**
816 * seq_write - write arbitrary data to buffer
817 * @seq: seq_file identifying the buffer to which data should be written
818 * @data: data address
819 * @len: number of bytes
820 *
821 * Return 0 on success, non-zero otherwise.
822 */
823int seq_write(struct seq_file *seq, const void *data, size_t len)
824{
825 if (seq->count + len < seq->size) {
826 memcpy(seq->buf + seq->count, data, len);
827 seq->count += len;
828 return 0;
829 }
830 seq_set_overflow(seq);
831 return -1;
832}
833EXPORT_SYMBOL(seq_write);
834
835/**
836 * seq_pad - write padding spaces to buffer
837 * @m: seq_file identifying the buffer to which data should be written
838 * @c: the byte to append after padding if non-zero
839 */
840void seq_pad(struct seq_file *m, char c)
841{
842 int size = m->pad_until - m->count;
843 if (size > 0) {
844 if (size + m->count > m->size) {
845 seq_set_overflow(m);
846 return;
847 }
848 memset(m->buf + m->count, ' ', size);
849 m->count += size;
850 }
851 if (c)
852 seq_putc(m, c);
853}
854EXPORT_SYMBOL(seq_pad);
855
856/* A complete analogue of print_hex_dump() */
857void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
858 int rowsize, int groupsize, const void *buf, size_t len,
859 bool ascii)
860{
861 const u8 *ptr = buf;
862 int i, linelen, remaining = len;
863 char *buffer;
864 size_t size;
865 int ret;
866
867 if (rowsize != 16 && rowsize != 32)
868 rowsize = 16;
869
870 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
871 linelen = min(remaining, rowsize);
872 remaining -= rowsize;
873
874 switch (prefix_type) {
875 case DUMP_PREFIX_ADDRESS:
876 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
877 break;
878 case DUMP_PREFIX_OFFSET:
879 seq_printf(m, "%s%.8x: ", prefix_str, i);
880 break;
881 default:
882 seq_printf(m, "%s", prefix_str);
883 break;
884 }
885
886 size = seq_get_buf(m, &buffer);
887 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
888 buffer, size, ascii);
889 seq_commit(m, ret < size ? ret : -1);
890
891 seq_putc(m, '\n');
892 }
893}
894EXPORT_SYMBOL(seq_hex_dump);
895
896struct list_head *seq_list_start(struct list_head *head, loff_t pos)
897{
898 struct list_head *lh;
899
900 list_for_each(lh, head)
901 if (pos-- == 0)
902 return lh;
903
904 return NULL;
905}
906EXPORT_SYMBOL(seq_list_start);
907
908struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
909{
910 if (!pos)
911 return head;
912
913 return seq_list_start(head, pos - 1);
914}
915EXPORT_SYMBOL(seq_list_start_head);
916
917struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
918{
919 struct list_head *lh;
920
921 lh = ((struct list_head *)v)->next;
922 ++*ppos;
923 return lh == head ? NULL : lh;
924}
925EXPORT_SYMBOL(seq_list_next);
926
927struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos)
928{
929 struct list_head *lh;
930
931 list_for_each_rcu(lh, head)
932 if (pos-- == 0)
933 return lh;
934
935 return NULL;
936}
937EXPORT_SYMBOL(seq_list_start_rcu);
938
939struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos)
940{
941 if (!pos)
942 return head;
943
944 return seq_list_start_rcu(head, pos - 1);
945}
946EXPORT_SYMBOL(seq_list_start_head_rcu);
947
948struct list_head *seq_list_next_rcu(void *v, struct list_head *head,
949 loff_t *ppos)
950{
951 struct list_head *lh;
952
953 lh = list_next_rcu((struct list_head *)v);
954 ++*ppos;
955 return lh == head ? NULL : lh;
956}
957EXPORT_SYMBOL(seq_list_next_rcu);
958
959/**
960 * seq_hlist_start - start an iteration of a hlist
961 * @head: the head of the hlist
962 * @pos: the start position of the sequence
963 *
964 * Called at seq_file->op->start().
965 */
966struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
967{
968 struct hlist_node *node;
969
970 hlist_for_each(node, head)
971 if (pos-- == 0)
972 return node;
973 return NULL;
974}
975EXPORT_SYMBOL(seq_hlist_start);
976
977/**
978 * seq_hlist_start_head - start an iteration of a hlist
979 * @head: the head of the hlist
980 * @pos: the start position of the sequence
981 *
982 * Called at seq_file->op->start(). Call this function if you want to
983 * print a header at the top of the output.
984 */
985struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
986{
987 if (!pos)
988 return SEQ_START_TOKEN;
989
990 return seq_hlist_start(head, pos - 1);
991}
992EXPORT_SYMBOL(seq_hlist_start_head);
993
994/**
995 * seq_hlist_next - move to the next position of the hlist
996 * @v: the current iterator
997 * @head: the head of the hlist
998 * @ppos: the current position
999 *
1000 * Called at seq_file->op->next().
1001 */
1002struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
1003 loff_t *ppos)
1004{
1005 struct hlist_node *node = v;
1006
1007 ++*ppos;
1008 if (v == SEQ_START_TOKEN)
1009 return head->first;
1010 else
1011 return node->next;
1012}
1013EXPORT_SYMBOL(seq_hlist_next);
1014
1015/**
1016 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
1017 * @head: the head of the hlist
1018 * @pos: the start position of the sequence
1019 *
1020 * Called at seq_file->op->start().
1021 *
1022 * This list-traversal primitive may safely run concurrently with
1023 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1024 * as long as the traversal is guarded by rcu_read_lock().
1025 */
1026struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
1027 loff_t pos)
1028{
1029 struct hlist_node *node;
1030
1031 __hlist_for_each_rcu(node, head)
1032 if (pos-- == 0)
1033 return node;
1034 return NULL;
1035}
1036EXPORT_SYMBOL(seq_hlist_start_rcu);
1037
1038/**
1039 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
1040 * @head: the head of the hlist
1041 * @pos: the start position of the sequence
1042 *
1043 * Called at seq_file->op->start(). Call this function if you want to
1044 * print a header at the top of the output.
1045 *
1046 * This list-traversal primitive may safely run concurrently with
1047 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1048 * as long as the traversal is guarded by rcu_read_lock().
1049 */
1050struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
1051 loff_t pos)
1052{
1053 if (!pos)
1054 return SEQ_START_TOKEN;
1055
1056 return seq_hlist_start_rcu(head, pos - 1);
1057}
1058EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1059
1060/**
1061 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1062 * @v: the current iterator
1063 * @head: the head of the hlist
1064 * @ppos: the current position
1065 *
1066 * Called at seq_file->op->next().
1067 *
1068 * This list-traversal primitive may safely run concurrently with
1069 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1070 * as long as the traversal is guarded by rcu_read_lock().
1071 */
1072struct hlist_node *seq_hlist_next_rcu(void *v,
1073 struct hlist_head *head,
1074 loff_t *ppos)
1075{
1076 struct hlist_node *node = v;
1077
1078 ++*ppos;
1079 if (v == SEQ_START_TOKEN)
1080 return rcu_dereference(head->first);
1081 else
1082 return rcu_dereference(node->next);
1083}
1084EXPORT_SYMBOL(seq_hlist_next_rcu);
1085
1086/**
1087 * seq_hlist_start_percpu - start an iteration of a percpu hlist array
1088 * @head: pointer to percpu array of struct hlist_heads
1089 * @cpu: pointer to cpu "cursor"
1090 * @pos: start position of sequence
1091 *
1092 * Called at seq_file->op->start().
1093 */
1094struct hlist_node *
1095seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1096{
1097 struct hlist_node *node;
1098
1099 for_each_possible_cpu(*cpu) {
1100 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1101 if (pos-- == 0)
1102 return node;
1103 }
1104 }
1105 return NULL;
1106}
1107EXPORT_SYMBOL(seq_hlist_start_percpu);
1108
1109/**
1110 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1111 * @v: pointer to current hlist_node
1112 * @head: pointer to percpu array of struct hlist_heads
1113 * @cpu: pointer to cpu "cursor"
1114 * @pos: start position of sequence
1115 *
1116 * Called at seq_file->op->next().
1117 */
1118struct hlist_node *
1119seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1120 int *cpu, loff_t *pos)
1121{
1122 struct hlist_node *node = v;
1123
1124 ++*pos;
1125
1126 if (node->next)
1127 return node->next;
1128
1129 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1130 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1131 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1132
1133 if (!hlist_empty(bucket))
1134 return bucket->first;
1135 }
1136 return NULL;
1137}
1138EXPORT_SYMBOL(seq_hlist_next_percpu);
1139
1140void __init seq_file_init(void)
1141{
1142 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
1143}