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TOMOYO Linux Cross Reference
Linux/fs/seq_file.c

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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/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 #include <linux/string_helpers.h>
 17 
 18 #include <linux/uaccess.h>
 19 #include <asm/page.h>
 20 
 21 static void seq_set_overflow(struct seq_file *m)
 22 {
 23         m->count = m->size;
 24 }
 25 
 26 static void *seq_buf_alloc(unsigned long size)
 27 {
 28         return kvmalloc(size, GFP_KERNEL);
 29 }
 30 
 31 /**
 32  *      seq_open -      initialize sequential file
 33  *      @file: file we initialize
 34  *      @op: method table describing the sequence
 35  *
 36  *      seq_open() sets @file, associating it with a sequence described
 37  *      by @op.  @op->start() sets the iterator up and returns the first
 38  *      element of sequence. @op->stop() shuts it down.  @op->next()
 39  *      returns the next element of sequence.  @op->show() prints element
 40  *      into the buffer.  In case of error ->start() and ->next() return
 41  *      ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
 42  *      returns 0 in case of success and negative number in case of error.
 43  *      Returning SEQ_SKIP means "discard this element and move on".
 44  *      Note: seq_open() will allocate a struct seq_file and store its
 45  *      pointer in @file->private_data. This pointer should not be modified.
 46  */
 47 int seq_open(struct file *file, const struct seq_operations *op)
 48 {
 49         struct seq_file *p;
 50 
 51         WARN_ON(file->private_data);
 52 
 53         p = kzalloc(sizeof(*p), GFP_KERNEL);
 54         if (!p)
 55                 return -ENOMEM;
 56 
 57         file->private_data = p;
 58 
 59         mutex_init(&p->lock);
 60         p->op = op;
 61 
 62         // No refcounting: the lifetime of 'p' is constrained
 63         // to the lifetime of the file.
 64         p->file = file;
 65 
 66         /*
 67          * Wrappers around seq_open(e.g. swaps_open) need to be
 68          * aware of this. If they set f_version themselves, they
 69          * should call seq_open first and then set f_version.
 70          */
 71         file->f_version = 0;
 72 
 73         /*
 74          * seq_files support lseek() and pread().  They do not implement
 75          * write() at all, but we clear FMODE_PWRITE here for historical
 76          * reasons.
 77          *
 78          * If a client of seq_files a) implements file.write() and b) wishes to
 79          * support pwrite() then that client will need to implement its own
 80          * file.open() which calls seq_open() and then sets FMODE_PWRITE.
 81          */
 82         file->f_mode &= ~FMODE_PWRITE;
 83         return 0;
 84 }
 85 EXPORT_SYMBOL(seq_open);
 86 
 87 static int traverse(struct seq_file *m, loff_t offset)
 88 {
 89         loff_t pos = 0, index;
 90         int error = 0;
 91         void *p;
 92 
 93         m->version = 0;
 94         index = 0;
 95         m->count = m->from = 0;
 96         if (!offset) {
 97                 m->index = index;
 98                 return 0;
 99         }
100         if (!m->buf) {
101                 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
102                 if (!m->buf)
103                         return -ENOMEM;
104         }
105         p = m->op->start(m, &index);
106         while (p) {
107                 error = PTR_ERR(p);
108                 if (IS_ERR(p))
109                         break;
110                 error = m->op->show(m, p);
111                 if (error < 0)
112                         break;
113                 if (unlikely(error)) {
114                         error = 0;
115                         m->count = 0;
116                 }
117                 if (seq_has_overflowed(m))
118                         goto Eoverflow;
119                 if (pos + m->count > offset) {
120                         m->from = offset - pos;
121                         m->count -= m->from;
122                         m->index = index;
123                         break;
124                 }
125                 pos += m->count;
126                 m->count = 0;
127                 if (pos == offset) {
128                         index++;
129                         m->index = index;
130                         break;
131                 }
132                 p = m->op->next(m, p, &index);
133         }
134         m->op->stop(m, p);
135         m->index = index;
136         return error;
137 
138 Eoverflow:
139         m->op->stop(m, p);
140         kvfree(m->buf);
141         m->count = 0;
142         m->buf = seq_buf_alloc(m->size <<= 1);
143         return !m->buf ? -ENOMEM : -EAGAIN;
144 }
145 
146 /**
147  *      seq_read -      ->read() method for sequential files.
148  *      @file: the file to read from
149  *      @buf: the buffer to read to
150  *      @size: the maximum number of bytes to read
151  *      @ppos: the current position in the file
152  *
153  *      Ready-made ->f_op->read()
154  */
155 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
156 {
157         struct seq_file *m = file->private_data;
158         size_t copied = 0;
159         loff_t pos;
160         size_t n;
161         void *p;
162         int err = 0;
163 
164         mutex_lock(&m->lock);
165 
166         /*
167          * seq_file->op->..m_start/m_stop/m_next may do special actions
168          * or optimisations based on the file->f_version, so we want to
169          * pass the file->f_version to those methods.
170          *
171          * seq_file->version is just copy of f_version, and seq_file
172          * methods can treat it simply as file version.
173          * It is copied in first and copied out after all operations.
174          * It is convenient to have it as  part of structure to avoid the
175          * need of passing another argument to all the seq_file methods.
176          */
177         m->version = file->f_version;
178 
179         /*
180          * if request is to read from zero offset, reset iterator to first
181          * record as it might have been already advanced by previous requests
182          */
183         if (*ppos == 0)
184                 m->index = 0;
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->from = 0;
221                         m->index++;
222                 }
223                 if (!size)
224                         goto Done;
225         }
226         /* we need at least one record in buffer */
227         pos = m->index;
228         p = m->op->start(m, &pos);
229         while (1) {
230                 err = PTR_ERR(p);
231                 if (!p || IS_ERR(p))
232                         break;
233                 err = m->op->show(m, p);
234                 if (err < 0)
235                         break;
236                 if (unlikely(err))
237                         m->count = 0;
238                 if (unlikely(!m->count)) {
239                         p = m->op->next(m, p, &pos);
240                         m->index = pos;
241                         continue;
242                 }
243                 if (m->count < m->size)
244                         goto Fill;
245                 m->op->stop(m, p);
246                 kvfree(m->buf);
247                 m->count = 0;
248                 m->buf = seq_buf_alloc(m->size <<= 1);
249                 if (!m->buf)
250                         goto Enomem;
251                 m->version = 0;
252                 pos = m->index;
253                 p = m->op->start(m, &pos);
254         }
255         m->op->stop(m, p);
256         m->count = 0;
257         goto Done;
258 Fill:
259         /* they want more? let's try to get some more */
260         while (m->count < size) {
261                 size_t offs = m->count;
262                 loff_t next = pos;
263                 p = m->op->next(m, p, &next);
264                 if (!p || IS_ERR(p)) {
265                         err = PTR_ERR(p);
266                         break;
267                 }
268                 err = m->op->show(m, p);
269                 if (seq_has_overflowed(m) || err) {
270                         m->count = offs;
271                         if (likely(err <= 0))
272                                 break;
273                 }
274                 pos = next;
275         }
276         m->op->stop(m, p);
277         n = min(m->count, size);
278         err = copy_to_user(buf, m->buf, n);
279         if (err)
280                 goto Efault;
281         copied += n;
282         m->count -= n;
283         if (m->count)
284                 m->from = n;
285         else
286                 pos++;
287         m->index = pos;
288 Done:
289         if (!copied)
290                 copied = err;
291         else {
292                 *ppos += copied;
293                 m->read_pos += copied;
294         }
295         file->f_version = m->version;
296         mutex_unlock(&m->lock);
297         return copied;
298 Enomem:
299         err = -ENOMEM;
300         goto Done;
301 Efault:
302         err = -EFAULT;
303         goto Done;
304 }
305 EXPORT_SYMBOL(seq_read);
306 
307 /**
308  *      seq_lseek -     ->llseek() method for sequential files.
309  *      @file: the file in question
310  *      @offset: new position
311  *      @whence: 0 for absolute, 1 for relative position
312  *
313  *      Ready-made ->f_op->llseek()
314  */
315 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
316 {
317         struct seq_file *m = file->private_data;
318         loff_t retval = -EINVAL;
319 
320         mutex_lock(&m->lock);
321         m->version = file->f_version;
322         switch (whence) {
323         case SEEK_CUR:
324                 offset += file->f_pos;
325         case SEEK_SET:
326                 if (offset < 0)
327                         break;
328                 retval = offset;
329                 if (offset != m->read_pos) {
330                         while ((retval = traverse(m, offset)) == -EAGAIN)
331                                 ;
332                         if (retval) {
333                                 /* with extreme prejudice... */
334                                 file->f_pos = 0;
335                                 m->read_pos = 0;
336                                 m->version = 0;
337                                 m->index = 0;
338                                 m->count = 0;
339                         } else {
340                                 m->read_pos = offset;
341                                 retval = file->f_pos = offset;
342                         }
343                 } else {
344                         file->f_pos = offset;
345                 }
346         }
347         file->f_version = m->version;
348         mutex_unlock(&m->lock);
349         return retval;
350 }
351 EXPORT_SYMBOL(seq_lseek);
352 
353 /**
354  *      seq_release -   free the structures associated with sequential file.
355  *      @file: file in question
356  *      @inode: its inode
357  *
358  *      Frees the structures associated with sequential file; can be used
359  *      as ->f_op->release() if you don't have private data to destroy.
360  */
361 int seq_release(struct inode *inode, struct file *file)
362 {
363         struct seq_file *m = file->private_data;
364         kvfree(m->buf);
365         kfree(m);
366         return 0;
367 }
368 EXPORT_SYMBOL(seq_release);
369 
370 /**
371  *      seq_escape -    print string into buffer, escaping some characters
372  *      @m:     target buffer
373  *      @s:     string
374  *      @esc:   set of characters that need escaping
375  *
376  *      Puts string into buffer, replacing each occurrence of character from
377  *      @esc with usual octal escape.
378  *      Use seq_has_overflowed() to check for errors.
379  */
380 void seq_escape(struct seq_file *m, const char *s, const char *esc)
381 {
382         char *buf;
383         size_t size = seq_get_buf(m, &buf);
384         int ret;
385 
386         ret = string_escape_str(s, buf, size, ESCAPE_OCTAL, esc);
387         seq_commit(m, ret < size ? ret : -1);
388 }
389 EXPORT_SYMBOL(seq_escape);
390 
391 void seq_vprintf(struct seq_file *m, const char *f, va_list args)
392 {
393         int len;
394 
395         if (m->count < m->size) {
396                 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
397                 if (m->count + len < m->size) {
398                         m->count += len;
399                         return;
400                 }
401         }
402         seq_set_overflow(m);
403 }
404 EXPORT_SYMBOL(seq_vprintf);
405 
406 void seq_printf(struct seq_file *m, const char *f, ...)
407 {
408         va_list args;
409 
410         va_start(args, f);
411         seq_vprintf(m, f, args);
412         va_end(args);
413 }
414 EXPORT_SYMBOL(seq_printf);
415 
416 /**
417  *      mangle_path -   mangle and copy path to buffer beginning
418  *      @s: buffer start
419  *      @p: beginning of path in above buffer
420  *      @esc: set of characters that need escaping
421  *
422  *      Copy the path from @p to @s, replacing each occurrence of character from
423  *      @esc with usual octal escape.
424  *      Returns pointer past last written character in @s, or NULL in case of
425  *      failure.
426  */
427 char *mangle_path(char *s, const char *p, const char *esc)
428 {
429         while (s <= p) {
430                 char c = *p++;
431                 if (!c) {
432                         return s;
433                 } else if (!strchr(esc, c)) {
434                         *s++ = c;
435                 } else if (s + 4 > p) {
436                         break;
437                 } else {
438                         *s++ = '\\';
439                         *s++ = '' + ((c & 0300) >> 6);
440                         *s++ = '' + ((c & 070) >> 3);
441                         *s++ = '' + (c & 07);
442                 }
443         }
444         return NULL;
445 }
446 EXPORT_SYMBOL(mangle_path);
447 
448 /**
449  * seq_path - seq_file interface to print a pathname
450  * @m: the seq_file handle
451  * @path: the struct path to print
452  * @esc: set of characters to escape in the output
453  *
454  * return the absolute path of 'path', as represented by the
455  * dentry / mnt pair in the path parameter.
456  */
457 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
458 {
459         char *buf;
460         size_t size = seq_get_buf(m, &buf);
461         int res = -1;
462 
463         if (size) {
464                 char *p = d_path(path, buf, size);
465                 if (!IS_ERR(p)) {
466                         char *end = mangle_path(buf, p, esc);
467                         if (end)
468                                 res = end - buf;
469                 }
470         }
471         seq_commit(m, res);
472 
473         return res;
474 }
475 EXPORT_SYMBOL(seq_path);
476 
477 /**
478  * seq_file_path - seq_file interface to print a pathname of a file
479  * @m: the seq_file handle
480  * @file: the struct file to print
481  * @esc: set of characters to escape in the output
482  *
483  * return the absolute path to the file.
484  */
485 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
486 {
487         return seq_path(m, &file->f_path, esc);
488 }
489 EXPORT_SYMBOL(seq_file_path);
490 
491 /*
492  * Same as seq_path, but relative to supplied root.
493  */
494 int seq_path_root(struct seq_file *m, const struct path *path,
495                   const struct path *root, const char *esc)
496 {
497         char *buf;
498         size_t size = seq_get_buf(m, &buf);
499         int res = -ENAMETOOLONG;
500 
501         if (size) {
502                 char *p;
503 
504                 p = __d_path(path, root, buf, size);
505                 if (!p)
506                         return SEQ_SKIP;
507                 res = PTR_ERR(p);
508                 if (!IS_ERR(p)) {
509                         char *end = mangle_path(buf, p, esc);
510                         if (end)
511                                 res = end - buf;
512                         else
513                                 res = -ENAMETOOLONG;
514                 }
515         }
516         seq_commit(m, res);
517 
518         return res < 0 && res != -ENAMETOOLONG ? res : 0;
519 }
520 
521 /*
522  * returns the path of the 'dentry' from the root of its filesystem.
523  */
524 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
525 {
526         char *buf;
527         size_t size = seq_get_buf(m, &buf);
528         int res = -1;
529 
530         if (size) {
531                 char *p = dentry_path(dentry, buf, size);
532                 if (!IS_ERR(p)) {
533                         char *end = mangle_path(buf, p, esc);
534                         if (end)
535                                 res = end - buf;
536                 }
537         }
538         seq_commit(m, res);
539 
540         return res;
541 }
542 EXPORT_SYMBOL(seq_dentry);
543 
544 static void *single_start(struct seq_file *p, loff_t *pos)
545 {
546         return NULL + (*pos == 0);
547 }
548 
549 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
550 {
551         ++*pos;
552         return NULL;
553 }
554 
555 static void single_stop(struct seq_file *p, void *v)
556 {
557 }
558 
559 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
560                 void *data)
561 {
562         struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
563         int res = -ENOMEM;
564 
565         if (op) {
566                 op->start = single_start;
567                 op->next = single_next;
568                 op->stop = single_stop;
569                 op->show = show;
570                 res = seq_open(file, op);
571                 if (!res)
572                         ((struct seq_file *)file->private_data)->private = data;
573                 else
574                         kfree(op);
575         }
576         return res;
577 }
578 EXPORT_SYMBOL(single_open);
579 
580 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
581                 void *data, size_t size)
582 {
583         char *buf = seq_buf_alloc(size);
584         int ret;
585         if (!buf)
586                 return -ENOMEM;
587         ret = single_open(file, show, data);
588         if (ret) {
589                 kvfree(buf);
590                 return ret;
591         }
592         ((struct seq_file *)file->private_data)->buf = buf;
593         ((struct seq_file *)file->private_data)->size = size;
594         return 0;
595 }
596 EXPORT_SYMBOL(single_open_size);
597 
598 int single_release(struct inode *inode, struct file *file)
599 {
600         const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
601         int res = seq_release(inode, file);
602         kfree(op);
603         return res;
604 }
605 EXPORT_SYMBOL(single_release);
606 
607 int seq_release_private(struct inode *inode, struct file *file)
608 {
609         struct seq_file *seq = file->private_data;
610 
611         kfree(seq->private);
612         seq->private = NULL;
613         return seq_release(inode, file);
614 }
615 EXPORT_SYMBOL(seq_release_private);
616 
617 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
618                 int psize)
619 {
620         int rc;
621         void *private;
622         struct seq_file *seq;
623 
624         private = kzalloc(psize, GFP_KERNEL);
625         if (private == NULL)
626                 goto out;
627 
628         rc = seq_open(f, ops);
629         if (rc < 0)
630                 goto out_free;
631 
632         seq = f->private_data;
633         seq->private = private;
634         return private;
635 
636 out_free:
637         kfree(private);
638 out:
639         return NULL;
640 }
641 EXPORT_SYMBOL(__seq_open_private);
642 
643 int seq_open_private(struct file *filp, const struct seq_operations *ops,
644                 int psize)
645 {
646         return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
647 }
648 EXPORT_SYMBOL(seq_open_private);
649 
650 void seq_putc(struct seq_file *m, char c)
651 {
652         if (m->count >= m->size)
653                 return;
654 
655         m->buf[m->count++] = c;
656 }
657 EXPORT_SYMBOL(seq_putc);
658 
659 void seq_puts(struct seq_file *m, const char *s)
660 {
661         int len = strlen(s);
662 
663         if (m->count + len >= m->size) {
664                 seq_set_overflow(m);
665                 return;
666         }
667         memcpy(m->buf + m->count, s, len);
668         m->count += len;
669 }
670 EXPORT_SYMBOL(seq_puts);
671 
672 /*
673  * A helper routine for putting decimal numbers without rich format of printf().
674  * only 'unsigned long long' is supported.
675  * This routine will put strlen(delimiter) + number into seq_file.
676  * This routine is very quick when you show lots of numbers.
677  * In usual cases, it will be better to use seq_printf(). It's easier to read.
678  */
679 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
680                          unsigned long long num)
681 {
682         int len;
683 
684         if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
685                 goto overflow;
686 
687         len = strlen(delimiter);
688         if (m->count + len >= m->size)
689                 goto overflow;
690 
691         memcpy(m->buf + m->count, delimiter, len);
692         m->count += len;
693 
694         if (m->count + 1 >= m->size)
695                 goto overflow;
696 
697         if (num < 10) {
698                 m->buf[m->count++] = num + '';
699                 return;
700         }
701 
702         len = num_to_str(m->buf + m->count, m->size - m->count, num);
703         if (!len)
704                 goto overflow;
705 
706         m->count += len;
707         return;
708 
709 overflow:
710         seq_set_overflow(m);
711 }
712 EXPORT_SYMBOL(seq_put_decimal_ull);
713 
714 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
715 {
716         int len;
717 
718         if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
719                 goto overflow;
720 
721         len = strlen(delimiter);
722         if (m->count + len >= m->size)
723                 goto overflow;
724 
725         memcpy(m->buf + m->count, delimiter, len);
726         m->count += len;
727 
728         if (m->count + 2 >= m->size)
729                 goto overflow;
730 
731         if (num < 0) {
732                 m->buf[m->count++] = '-';
733                 num = -num;
734         }
735 
736         if (num < 10) {
737                 m->buf[m->count++] = num + '';
738                 return;
739         }
740 
741         len = num_to_str(m->buf + m->count, m->size - m->count, num);
742         if (!len)
743                 goto overflow;
744 
745         m->count += len;
746         return;
747 
748 overflow:
749         seq_set_overflow(m);
750 }
751 EXPORT_SYMBOL(seq_put_decimal_ll);
752 
753 /**
754  * seq_write - write arbitrary data to buffer
755  * @seq: seq_file identifying the buffer to which data should be written
756  * @data: data address
757  * @len: number of bytes
758  *
759  * Return 0 on success, non-zero otherwise.
760  */
761 int seq_write(struct seq_file *seq, const void *data, size_t len)
762 {
763         if (seq->count + len < seq->size) {
764                 memcpy(seq->buf + seq->count, data, len);
765                 seq->count += len;
766                 return 0;
767         }
768         seq_set_overflow(seq);
769         return -1;
770 }
771 EXPORT_SYMBOL(seq_write);
772 
773 /**
774  * seq_pad - write padding spaces to buffer
775  * @m: seq_file identifying the buffer to which data should be written
776  * @c: the byte to append after padding if non-zero
777  */
778 void seq_pad(struct seq_file *m, char c)
779 {
780         int size = m->pad_until - m->count;
781         if (size > 0)
782                 seq_printf(m, "%*s", size, "");
783         if (c)
784                 seq_putc(m, c);
785 }
786 EXPORT_SYMBOL(seq_pad);
787 
788 /* A complete analogue of print_hex_dump() */
789 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
790                   int rowsize, int groupsize, const void *buf, size_t len,
791                   bool ascii)
792 {
793         const u8 *ptr = buf;
794         int i, linelen, remaining = len;
795         char *buffer;
796         size_t size;
797         int ret;
798 
799         if (rowsize != 16 && rowsize != 32)
800                 rowsize = 16;
801 
802         for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
803                 linelen = min(remaining, rowsize);
804                 remaining -= rowsize;
805 
806                 switch (prefix_type) {
807                 case DUMP_PREFIX_ADDRESS:
808                         seq_printf(m, "%s%p: ", prefix_str, ptr + i);
809                         break;
810                 case DUMP_PREFIX_OFFSET:
811                         seq_printf(m, "%s%.8x: ", prefix_str, i);
812                         break;
813                 default:
814                         seq_printf(m, "%s", prefix_str);
815                         break;
816                 }
817 
818                 size = seq_get_buf(m, &buffer);
819                 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
820                                          buffer, size, ascii);
821                 seq_commit(m, ret < size ? ret : -1);
822 
823                 seq_putc(m, '\n');
824         }
825 }
826 EXPORT_SYMBOL(seq_hex_dump);
827 
828 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
829 {
830         struct list_head *lh;
831 
832         list_for_each(lh, head)
833                 if (pos-- == 0)
834                         return lh;
835 
836         return NULL;
837 }
838 EXPORT_SYMBOL(seq_list_start);
839 
840 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
841 {
842         if (!pos)
843                 return head;
844 
845         return seq_list_start(head, pos - 1);
846 }
847 EXPORT_SYMBOL(seq_list_start_head);
848 
849 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
850 {
851         struct list_head *lh;
852 
853         lh = ((struct list_head *)v)->next;
854         ++*ppos;
855         return lh == head ? NULL : lh;
856 }
857 EXPORT_SYMBOL(seq_list_next);
858 
859 /**
860  * seq_hlist_start - 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().
865  */
866 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
867 {
868         struct hlist_node *node;
869 
870         hlist_for_each(node, head)
871                 if (pos-- == 0)
872                         return node;
873         return NULL;
874 }
875 EXPORT_SYMBOL(seq_hlist_start);
876 
877 /**
878  * seq_hlist_start_head - start an iteration of a hlist
879  * @head: the head of the hlist
880  * @pos:  the start position of the sequence
881  *
882  * Called at seq_file->op->start(). Call this function if you want to
883  * print a header at the top of the output.
884  */
885 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
886 {
887         if (!pos)
888                 return SEQ_START_TOKEN;
889 
890         return seq_hlist_start(head, pos - 1);
891 }
892 EXPORT_SYMBOL(seq_hlist_start_head);
893 
894 /**
895  * seq_hlist_next - move to the next position of the hlist
896  * @v:    the current iterator
897  * @head: the head of the hlist
898  * @ppos: the current position
899  *
900  * Called at seq_file->op->next().
901  */
902 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
903                                   loff_t *ppos)
904 {
905         struct hlist_node *node = v;
906 
907         ++*ppos;
908         if (v == SEQ_START_TOKEN)
909                 return head->first;
910         else
911                 return node->next;
912 }
913 EXPORT_SYMBOL(seq_hlist_next);
914 
915 /**
916  * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
917  * @head: the head of the hlist
918  * @pos:  the start position of the sequence
919  *
920  * Called at seq_file->op->start().
921  *
922  * This list-traversal primitive may safely run concurrently with
923  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
924  * as long as the traversal is guarded by rcu_read_lock().
925  */
926 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
927                                        loff_t pos)
928 {
929         struct hlist_node *node;
930 
931         __hlist_for_each_rcu(node, head)
932                 if (pos-- == 0)
933                         return node;
934         return NULL;
935 }
936 EXPORT_SYMBOL(seq_hlist_start_rcu);
937 
938 /**
939  * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
940  * @head: the head of the hlist
941  * @pos:  the start position of the sequence
942  *
943  * Called at seq_file->op->start(). Call this function if you want to
944  * print a header at the top of the output.
945  *
946  * This list-traversal primitive may safely run concurrently with
947  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
948  * as long as the traversal is guarded by rcu_read_lock().
949  */
950 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
951                                             loff_t pos)
952 {
953         if (!pos)
954                 return SEQ_START_TOKEN;
955 
956         return seq_hlist_start_rcu(head, pos - 1);
957 }
958 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
959 
960 /**
961  * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
962  * @v:    the current iterator
963  * @head: the head of the hlist
964  * @ppos: the current position
965  *
966  * Called at seq_file->op->next().
967  *
968  * This list-traversal primitive may safely run concurrently with
969  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
970  * as long as the traversal is guarded by rcu_read_lock().
971  */
972 struct hlist_node *seq_hlist_next_rcu(void *v,
973                                       struct hlist_head *head,
974                                       loff_t *ppos)
975 {
976         struct hlist_node *node = v;
977 
978         ++*ppos;
979         if (v == SEQ_START_TOKEN)
980                 return rcu_dereference(head->first);
981         else
982                 return rcu_dereference(node->next);
983 }
984 EXPORT_SYMBOL(seq_hlist_next_rcu);
985 
986 /**
987  * seq_hlist_start_precpu - start an iteration of a percpu hlist array
988  * @head: pointer to percpu array of struct hlist_heads
989  * @cpu:  pointer to cpu "cursor"
990  * @pos:  start position of sequence
991  *
992  * Called at seq_file->op->start().
993  */
994 struct hlist_node *
995 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
996 {
997         struct hlist_node *node;
998 
999         for_each_possible_cpu(*cpu) {
1000                 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1001                         if (pos-- == 0)
1002                                 return node;
1003                 }
1004         }
1005         return NULL;
1006 }
1007 EXPORT_SYMBOL(seq_hlist_start_percpu);
1008 
1009 /**
1010  * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1011  * @v:    pointer to current hlist_node
1012  * @head: pointer to percpu array of struct hlist_heads
1013  * @cpu:  pointer to cpu "cursor"
1014  * @pos:  start position of sequence
1015  *
1016  * Called at seq_file->op->next().
1017  */
1018 struct hlist_node *
1019 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1020                         int *cpu, loff_t *pos)
1021 {
1022         struct hlist_node *node = v;
1023 
1024         ++*pos;
1025 
1026         if (node->next)
1027                 return node->next;
1028 
1029         for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1030              *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1031                 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1032 
1033                 if (!hlist_empty(bucket))
1034                         return bucket->first;
1035         }
1036         return NULL;
1037 }
1038 EXPORT_SYMBOL(seq_hlist_next_percpu);
1039 

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