1 // SPDX-License-Identifier: GPL-2.0
5 * helper functions for making synthetic files from sequences of records.
6 * initial implementation -- AV, Oct 2001.
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/cache.h>
13 #include <linux/export.h>
14 #include <linux/seq_file.h>
15 #include <linux/vmalloc.h>
16 #include <linux/slab.h>
17 #include <linux/cred.h>
19 #include <linux/printk.h>
20 #include <linux/string_helpers.h>
21 #include <linux/uio.h>
23 #include <linux/uaccess.h>
26 static struct kmem_cache
*seq_file_cache __ro_after_init
;
28 static void seq_set_overflow(struct seq_file
*m
)
33 static void *seq_buf_alloc(unsigned long size
)
35 if (unlikely(size
> MAX_RW_COUNT
))
38 return kvmalloc(size
, GFP_KERNEL_ACCOUNT
);
42 * seq_open - initialize sequential file
43 * @file: file we initialize
44 * @op: method table describing the sequence
46 * seq_open() sets @file, associating it with a sequence described
47 * by @op. @op->start() sets the iterator up and returns the first
48 * element of sequence. @op->stop() shuts it down. @op->next()
49 * returns the next element of sequence. @op->show() prints element
50 * into the buffer. In case of error ->start() and ->next() return
51 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
52 * returns 0 in case of success and negative number in case of error.
53 * Returning SEQ_SKIP means "discard this element and move on".
54 * Note: seq_open() will allocate a struct seq_file and store its
55 * pointer in @file->private_data. This pointer should not be modified.
57 int seq_open(struct file
*file
, const struct seq_operations
*op
)
61 WARN_ON(file
->private_data
);
63 p
= kmem_cache_zalloc(seq_file_cache
, GFP_KERNEL
);
67 file
->private_data
= p
;
72 // No refcounting: the lifetime of 'p' is constrained
73 // to the lifetime of the file.
77 * seq_files support lseek() and pread(). They do not implement
78 * write() at all, but we clear FMODE_PWRITE here for historical
81 * If a client of seq_files a) implements file.write() and b) wishes to
82 * support pwrite() then that client will need to implement its own
83 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
85 file
->f_mode
&= ~FMODE_PWRITE
;
88 EXPORT_SYMBOL(seq_open
);
90 static int traverse(struct seq_file
*m
, loff_t offset
)
97 m
->count
= m
->from
= 0;
102 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
106 p
= m
->op
->start(m
, &m
->index
);
111 error
= m
->op
->show(m
, p
);
114 if (unlikely(error
)) {
118 if (seq_has_overflowed(m
))
120 p
= m
->op
->next(m
, p
, &m
->index
);
121 if (pos
+ m
->count
> offset
) {
122 m
->from
= offset
- pos
;
138 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
139 return !m
->buf
? -ENOMEM
: -EAGAIN
;
143 * seq_read - ->read() method for sequential files.
144 * @file: the file to read from
145 * @buf: the buffer to read to
146 * @size: the maximum number of bytes to read
147 * @ppos: the current position in the file
149 * Ready-made ->f_op->read()
151 ssize_t
seq_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*ppos
)
153 struct iovec iov
= { .iov_base
= buf
, .iov_len
= size
};
155 struct iov_iter iter
;
158 init_sync_kiocb(&kiocb
, file
);
159 iov_iter_init(&iter
, READ
, &iov
, 1, size
);
161 kiocb
.ki_pos
= *ppos
;
162 ret
= seq_read_iter(&kiocb
, &iter
);
163 *ppos
= kiocb
.ki_pos
;
166 EXPORT_SYMBOL(seq_read
);
169 * Ready-made ->f_op->read_iter()
171 ssize_t
seq_read_iter(struct kiocb
*iocb
, struct iov_iter
*iter
)
173 struct seq_file
*m
= iocb
->ki_filp
->private_data
;
179 if (!iov_iter_count(iter
))
182 mutex_lock(&m
->lock
);
185 * if request is to read from zero offset, reset iterator to first
186 * record as it might have been already advanced by previous requests
188 if (iocb
->ki_pos
== 0) {
193 /* Don't assume ki_pos is where we left it */
194 if (unlikely(iocb
->ki_pos
!= m
->read_pos
)) {
195 while ((err
= traverse(m
, iocb
->ki_pos
)) == -EAGAIN
)
198 /* With prejudice... */
204 m
->read_pos
= iocb
->ki_pos
;
208 /* grab buffer if we didn't have one */
210 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
214 // something left in the buffer - copy it out first
216 n
= copy_to_iter(m
->buf
+ m
->from
, m
->count
, iter
);
220 if (m
->count
) // hadn't managed to copy everything
223 // get a non-empty record in the buffer
225 p
= m
->op
->start(m
, &m
->index
);
228 if (!p
|| IS_ERR(p
)) // EOF or an error
230 err
= m
->op
->show(m
, p
);
231 if (err
< 0) // hard error
233 if (unlikely(err
)) // ->show() says "skip it"
235 if (unlikely(!m
->count
)) { // empty record
236 p
= m
->op
->next(m
, p
, &m
->index
);
239 if (!seq_has_overflowed(m
)) // got it
241 // need a bigger buffer
245 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
248 p
= m
->op
->start(m
, &m
->index
);
255 // one non-empty record is in the buffer; if they want more,
256 // try to fit more in, but in any case we need to advance
257 // the iterator once for every record shown.
259 size_t offs
= m
->count
;
260 loff_t pos
= m
->index
;
262 p
= m
->op
->next(m
, p
, &m
->index
);
263 if (pos
== m
->index
) {
264 pr_info_ratelimited("buggy .next function %ps did not update position index\n",
268 if (!p
|| IS_ERR(p
)) // no next record for us
270 if (m
->count
>= iov_iter_count(iter
))
272 err
= m
->op
->show(m
, p
);
273 if (err
> 0) { // ->show() says "skip it"
275 } else if (err
|| seq_has_overflowed(m
)) {
281 n
= copy_to_iter(m
->buf
, m
->count
, iter
);
286 if (unlikely(!copied
)) {
287 copied
= m
->count
? -EFAULT
: err
;
289 iocb
->ki_pos
+= copied
;
290 m
->read_pos
+= copied
;
292 mutex_unlock(&m
->lock
);
298 EXPORT_SYMBOL(seq_read_iter
);
301 * seq_lseek - ->llseek() method for sequential files.
302 * @file: the file in question
303 * @offset: new position
304 * @whence: 0 for absolute, 1 for relative position
306 * Ready-made ->f_op->llseek()
308 loff_t
seq_lseek(struct file
*file
, loff_t offset
, int whence
)
310 struct seq_file
*m
= file
->private_data
;
311 loff_t retval
= -EINVAL
;
313 mutex_lock(&m
->lock
);
316 offset
+= file
->f_pos
;
322 if (offset
!= m
->read_pos
) {
323 while ((retval
= traverse(m
, offset
)) == -EAGAIN
)
326 /* with extreme prejudice... */
332 m
->read_pos
= offset
;
333 retval
= file
->f_pos
= offset
;
336 file
->f_pos
= offset
;
339 mutex_unlock(&m
->lock
);
342 EXPORT_SYMBOL(seq_lseek
);
345 * seq_release - free the structures associated with sequential file.
346 * @file: file in question
349 * Frees the structures associated with sequential file; can be used
350 * as ->f_op->release() if you don't have private data to destroy.
352 int seq_release(struct inode
*inode
, struct file
*file
)
354 struct seq_file
*m
= file
->private_data
;
356 kmem_cache_free(seq_file_cache
, m
);
359 EXPORT_SYMBOL(seq_release
);
362 * seq_escape_mem - print data into buffer, escaping some characters
364 * @src: source buffer
365 * @len: size of source buffer
366 * @flags: flags to pass to string_escape_mem()
367 * @esc: set of characters that need escaping
369 * Puts data into buffer, replacing each occurrence of character from
370 * given class (defined by @flags and @esc) with printable escaped sequence.
372 * Use seq_has_overflowed() to check for errors.
374 void seq_escape_mem(struct seq_file
*m
, const char *src
, size_t len
,
375 unsigned int flags
, const char *esc
)
378 size_t size
= seq_get_buf(m
, &buf
);
381 ret
= string_escape_mem(src
, len
, buf
, size
, flags
, esc
);
382 seq_commit(m
, ret
< size
? ret
: -1);
384 EXPORT_SYMBOL(seq_escape_mem
);
387 * seq_escape - print string into buffer, escaping some characters
390 * @esc: set of characters that need escaping
392 * Puts string into buffer, replacing each occurrence of character from
393 * @esc with usual octal escape.
394 * Use seq_has_overflowed() to check for errors.
396 void seq_escape(struct seq_file
*m
, const char *s
, const char *esc
)
398 seq_escape_str(m
, s
, ESCAPE_OCTAL
, esc
);
400 EXPORT_SYMBOL(seq_escape
);
402 void seq_vprintf(struct seq_file
*m
, const char *f
, va_list args
)
406 if (m
->count
< m
->size
) {
407 len
= vsnprintf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
, args
);
408 if (m
->count
+ len
< m
->size
) {
415 EXPORT_SYMBOL(seq_vprintf
);
417 void seq_printf(struct seq_file
*m
, const char *f
, ...)
422 seq_vprintf(m
, f
, args
);
425 EXPORT_SYMBOL(seq_printf
);
427 #ifdef CONFIG_BINARY_PRINTF
428 void seq_bprintf(struct seq_file
*m
, const char *f
, const u32
*binary
)
432 if (m
->count
< m
->size
) {
433 len
= bstr_printf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
,
435 if (m
->count
+ len
< m
->size
) {
442 EXPORT_SYMBOL(seq_bprintf
);
443 #endif /* CONFIG_BINARY_PRINTF */
446 * mangle_path - mangle and copy path to buffer beginning
448 * @p: beginning of path in above buffer
449 * @esc: set of characters that need escaping
451 * Copy the path from @p to @s, replacing each occurrence of character from
452 * @esc with usual octal escape.
453 * Returns pointer past last written character in @s, or NULL in case of
456 char *mangle_path(char *s
, const char *p
, const char *esc
)
462 } else if (!strchr(esc
, c
)) {
464 } else if (s
+ 4 > p
) {
468 *s
++ = '0' + ((c
& 0300) >> 6);
469 *s
++ = '0' + ((c
& 070) >> 3);
470 *s
++ = '0' + (c
& 07);
475 EXPORT_SYMBOL(mangle_path
);
478 * seq_path - seq_file interface to print a pathname
479 * @m: the seq_file handle
480 * @path: the struct path to print
481 * @esc: set of characters to escape in the output
483 * return the absolute path of 'path', as represented by the
484 * dentry / mnt pair in the path parameter.
486 int seq_path(struct seq_file
*m
, const struct path
*path
, const char *esc
)
489 size_t size
= seq_get_buf(m
, &buf
);
493 char *p
= d_path(path
, buf
, size
);
495 char *end
= mangle_path(buf
, p
, esc
);
504 EXPORT_SYMBOL(seq_path
);
507 * seq_file_path - seq_file interface to print a pathname of a file
508 * @m: the seq_file handle
509 * @file: the struct file to print
510 * @esc: set of characters to escape in the output
512 * return the absolute path to the file.
514 int seq_file_path(struct seq_file
*m
, struct file
*file
, const char *esc
)
516 return seq_path(m
, &file
->f_path
, esc
);
518 EXPORT_SYMBOL(seq_file_path
);
521 * Same as seq_path, but relative to supplied root.
523 int seq_path_root(struct seq_file
*m
, const struct path
*path
,
524 const struct path
*root
, const char *esc
)
527 size_t size
= seq_get_buf(m
, &buf
);
528 int res
= -ENAMETOOLONG
;
533 p
= __d_path(path
, root
, buf
, size
);
538 char *end
= mangle_path(buf
, p
, esc
);
547 return res
< 0 && res
!= -ENAMETOOLONG
? res
: 0;
551 * returns the path of the 'dentry' from the root of its filesystem.
553 int seq_dentry(struct seq_file
*m
, struct dentry
*dentry
, const char *esc
)
556 size_t size
= seq_get_buf(m
, &buf
);
560 char *p
= dentry_path(dentry
, buf
, size
);
562 char *end
= mangle_path(buf
, p
, esc
);
571 EXPORT_SYMBOL(seq_dentry
);
573 static void *single_start(struct seq_file
*p
, loff_t
*pos
)
575 return NULL
+ (*pos
== 0);
578 static void *single_next(struct seq_file
*p
, void *v
, loff_t
*pos
)
584 static void single_stop(struct seq_file
*p
, void *v
)
588 int single_open(struct file
*file
, int (*show
)(struct seq_file
*, void *),
591 struct seq_operations
*op
= kmalloc(sizeof(*op
), GFP_KERNEL_ACCOUNT
);
595 op
->start
= single_start
;
596 op
->next
= single_next
;
597 op
->stop
= single_stop
;
599 res
= seq_open(file
, op
);
601 ((struct seq_file
*)file
->private_data
)->private = data
;
607 EXPORT_SYMBOL(single_open
);
609 int single_open_size(struct file
*file
, int (*show
)(struct seq_file
*, void *),
610 void *data
, size_t size
)
612 char *buf
= seq_buf_alloc(size
);
616 ret
= single_open(file
, show
, data
);
621 ((struct seq_file
*)file
->private_data
)->buf
= buf
;
622 ((struct seq_file
*)file
->private_data
)->size
= size
;
625 EXPORT_SYMBOL(single_open_size
);
627 int single_release(struct inode
*inode
, struct file
*file
)
629 const struct seq_operations
*op
= ((struct seq_file
*)file
->private_data
)->op
;
630 int res
= seq_release(inode
, file
);
634 EXPORT_SYMBOL(single_release
);
636 int seq_release_private(struct inode
*inode
, struct file
*file
)
638 struct seq_file
*seq
= file
->private_data
;
642 return seq_release(inode
, file
);
644 EXPORT_SYMBOL(seq_release_private
);
646 void *__seq_open_private(struct file
*f
, const struct seq_operations
*ops
,
651 struct seq_file
*seq
;
653 private = kzalloc(psize
, GFP_KERNEL_ACCOUNT
);
657 rc
= seq_open(f
, ops
);
661 seq
= f
->private_data
;
662 seq
->private = private;
670 EXPORT_SYMBOL(__seq_open_private
);
672 int seq_open_private(struct file
*filp
, const struct seq_operations
*ops
,
675 return __seq_open_private(filp
, ops
, psize
) ? 0 : -ENOMEM
;
677 EXPORT_SYMBOL(seq_open_private
);
679 void seq_putc(struct seq_file
*m
, char c
)
681 if (m
->count
>= m
->size
)
684 m
->buf
[m
->count
++] = c
;
686 EXPORT_SYMBOL(seq_putc
);
688 void seq_puts(struct seq_file
*m
, const char *s
)
692 if (m
->count
+ len
>= m
->size
) {
696 memcpy(m
->buf
+ m
->count
, s
, len
);
699 EXPORT_SYMBOL(seq_puts
);
702 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers
703 * without rich format of printf().
704 * only 'unsigned long long' is supported.
705 * @m: seq_file identifying the buffer to which data should be written
706 * @delimiter: a string which is printed before the number
708 * @width: a minimum field width
710 * This routine will put strlen(delimiter) + number into seq_filed.
711 * This routine is very quick when you show lots of numbers.
712 * In usual cases, it will be better to use seq_printf(). It's easier to read.
714 void seq_put_decimal_ull_width(struct seq_file
*m
, const char *delimiter
,
715 unsigned long long num
, unsigned int width
)
719 if (m
->count
+ 2 >= m
->size
) /* we'll write 2 bytes at least */
722 if (delimiter
&& delimiter
[0]) {
723 if (delimiter
[1] == 0)
724 seq_putc(m
, delimiter
[0]);
726 seq_puts(m
, delimiter
);
732 if (m
->count
+ width
>= m
->size
)
735 len
= num_to_str(m
->buf
+ m
->count
, m
->size
- m
->count
, num
, width
);
746 void seq_put_decimal_ull(struct seq_file
*m
, const char *delimiter
,
747 unsigned long long num
)
749 return seq_put_decimal_ull_width(m
, delimiter
, num
, 0);
751 EXPORT_SYMBOL(seq_put_decimal_ull
);
754 * seq_put_hex_ll - put a number in hexadecimal notation
755 * @m: seq_file identifying the buffer to which data should be written
756 * @delimiter: a string which is printed before the number
758 * @width: a minimum field width
760 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
762 * This routine is very quick when you show lots of numbers.
763 * In usual cases, it will be better to use seq_printf(). It's easier to read.
765 void seq_put_hex_ll(struct seq_file
*m
, const char *delimiter
,
766 unsigned long long v
, unsigned int width
)
771 if (delimiter
&& delimiter
[0]) {
772 if (delimiter
[1] == 0)
773 seq_putc(m
, delimiter
[0]);
775 seq_puts(m
, delimiter
);
778 /* If x is 0, the result of __builtin_clzll is undefined */
782 len
= (sizeof(v
) * 8 - __builtin_clzll(v
) + 3) / 4;
787 if (m
->count
+ len
> m
->size
) {
792 for (i
= len
- 1; i
>= 0; i
--) {
793 m
->buf
[m
->count
+ i
] = hex_asc
[0xf & v
];
799 void seq_put_decimal_ll(struct seq_file
*m
, const char *delimiter
, long long num
)
803 if (m
->count
+ 3 >= m
->size
) /* we'll write 2 bytes at least */
806 if (delimiter
&& delimiter
[0]) {
807 if (delimiter
[1] == 0)
808 seq_putc(m
, delimiter
[0]);
810 seq_puts(m
, delimiter
);
813 if (m
->count
+ 2 >= m
->size
)
817 m
->buf
[m
->count
++] = '-';
822 m
->buf
[m
->count
++] = num
+ '0';
826 len
= num_to_str(m
->buf
+ m
->count
, m
->size
- m
->count
, num
, 0);
836 EXPORT_SYMBOL(seq_put_decimal_ll
);
839 * seq_write - write arbitrary data to buffer
840 * @seq: seq_file identifying the buffer to which data should be written
841 * @data: data address
842 * @len: number of bytes
844 * Return 0 on success, non-zero otherwise.
846 int seq_write(struct seq_file
*seq
, const void *data
, size_t len
)
848 if (seq
->count
+ len
< seq
->size
) {
849 memcpy(seq
->buf
+ seq
->count
, data
, len
);
853 seq_set_overflow(seq
);
856 EXPORT_SYMBOL(seq_write
);
859 * seq_pad - write padding spaces to buffer
860 * @m: seq_file identifying the buffer to which data should be written
861 * @c: the byte to append after padding if non-zero
863 void seq_pad(struct seq_file
*m
, char c
)
865 int size
= m
->pad_until
- m
->count
;
867 if (size
+ m
->count
> m
->size
) {
871 memset(m
->buf
+ m
->count
, ' ', size
);
877 EXPORT_SYMBOL(seq_pad
);
879 /* A complete analogue of print_hex_dump() */
880 void seq_hex_dump(struct seq_file
*m
, const char *prefix_str
, int prefix_type
,
881 int rowsize
, int groupsize
, const void *buf
, size_t len
,
885 int i
, linelen
, remaining
= len
;
890 if (rowsize
!= 16 && rowsize
!= 32)
893 for (i
= 0; i
< len
&& !seq_has_overflowed(m
); i
+= rowsize
) {
894 linelen
= min(remaining
, rowsize
);
895 remaining
-= rowsize
;
897 switch (prefix_type
) {
898 case DUMP_PREFIX_ADDRESS
:
899 seq_printf(m
, "%s%p: ", prefix_str
, ptr
+ i
);
901 case DUMP_PREFIX_OFFSET
:
902 seq_printf(m
, "%s%.8x: ", prefix_str
, i
);
905 seq_printf(m
, "%s", prefix_str
);
909 size
= seq_get_buf(m
, &buffer
);
910 ret
= hex_dump_to_buffer(ptr
+ i
, linelen
, rowsize
, groupsize
,
911 buffer
, size
, ascii
);
912 seq_commit(m
, ret
< size
? ret
: -1);
917 EXPORT_SYMBOL(seq_hex_dump
);
919 struct list_head
*seq_list_start(struct list_head
*head
, loff_t pos
)
921 struct list_head
*lh
;
923 list_for_each(lh
, head
)
929 EXPORT_SYMBOL(seq_list_start
);
931 struct list_head
*seq_list_start_head(struct list_head
*head
, loff_t pos
)
936 return seq_list_start(head
, pos
- 1);
938 EXPORT_SYMBOL(seq_list_start_head
);
940 struct list_head
*seq_list_next(void *v
, struct list_head
*head
, loff_t
*ppos
)
942 struct list_head
*lh
;
944 lh
= ((struct list_head
*)v
)->next
;
946 return lh
== head
? NULL
: lh
;
948 EXPORT_SYMBOL(seq_list_next
);
951 * seq_hlist_start - start an iteration of a hlist
952 * @head: the head of the hlist
953 * @pos: the start position of the sequence
955 * Called at seq_file->op->start().
957 struct hlist_node
*seq_hlist_start(struct hlist_head
*head
, loff_t pos
)
959 struct hlist_node
*node
;
961 hlist_for_each(node
, head
)
966 EXPORT_SYMBOL(seq_hlist_start
);
969 * seq_hlist_start_head - start an iteration of a hlist
970 * @head: the head of the hlist
971 * @pos: the start position of the sequence
973 * Called at seq_file->op->start(). Call this function if you want to
974 * print a header at the top of the output.
976 struct hlist_node
*seq_hlist_start_head(struct hlist_head
*head
, loff_t pos
)
979 return SEQ_START_TOKEN
;
981 return seq_hlist_start(head
, pos
- 1);
983 EXPORT_SYMBOL(seq_hlist_start_head
);
986 * seq_hlist_next - move to the next position of the hlist
987 * @v: the current iterator
988 * @head: the head of the hlist
989 * @ppos: the current position
991 * Called at seq_file->op->next().
993 struct hlist_node
*seq_hlist_next(void *v
, struct hlist_head
*head
,
996 struct hlist_node
*node
= v
;
999 if (v
== SEQ_START_TOKEN
)
1004 EXPORT_SYMBOL(seq_hlist_next
);
1007 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
1008 * @head: the head of the hlist
1009 * @pos: the start position of the sequence
1011 * Called at seq_file->op->start().
1013 * This list-traversal primitive may safely run concurrently with
1014 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1015 * as long as the traversal is guarded by rcu_read_lock().
1017 struct hlist_node
*seq_hlist_start_rcu(struct hlist_head
*head
,
1020 struct hlist_node
*node
;
1022 __hlist_for_each_rcu(node
, head
)
1027 EXPORT_SYMBOL(seq_hlist_start_rcu
);
1030 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
1031 * @head: the head of the hlist
1032 * @pos: the start position of the sequence
1034 * Called at seq_file->op->start(). Call this function if you want to
1035 * print a header at the top of the output.
1037 * This list-traversal primitive may safely run concurrently with
1038 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1039 * as long as the traversal is guarded by rcu_read_lock().
1041 struct hlist_node
*seq_hlist_start_head_rcu(struct hlist_head
*head
,
1045 return SEQ_START_TOKEN
;
1047 return seq_hlist_start_rcu(head
, pos
- 1);
1049 EXPORT_SYMBOL(seq_hlist_start_head_rcu
);
1052 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1053 * @v: the current iterator
1054 * @head: the head of the hlist
1055 * @ppos: the current position
1057 * Called at seq_file->op->next().
1059 * This list-traversal primitive may safely run concurrently with
1060 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1061 * as long as the traversal is guarded by rcu_read_lock().
1063 struct hlist_node
*seq_hlist_next_rcu(void *v
,
1064 struct hlist_head
*head
,
1067 struct hlist_node
*node
= v
;
1070 if (v
== SEQ_START_TOKEN
)
1071 return rcu_dereference(head
->first
);
1073 return rcu_dereference(node
->next
);
1075 EXPORT_SYMBOL(seq_hlist_next_rcu
);
1078 * seq_hlist_start_percpu - start an iteration of a percpu hlist array
1079 * @head: pointer to percpu array of struct hlist_heads
1080 * @cpu: pointer to cpu "cursor"
1081 * @pos: start position of sequence
1083 * Called at seq_file->op->start().
1086 seq_hlist_start_percpu(struct hlist_head __percpu
*head
, int *cpu
, loff_t pos
)
1088 struct hlist_node
*node
;
1090 for_each_possible_cpu(*cpu
) {
1091 hlist_for_each(node
, per_cpu_ptr(head
, *cpu
)) {
1098 EXPORT_SYMBOL(seq_hlist_start_percpu
);
1101 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1102 * @v: pointer to current hlist_node
1103 * @head: pointer to percpu array of struct hlist_heads
1104 * @cpu: pointer to cpu "cursor"
1105 * @pos: start position of sequence
1107 * Called at seq_file->op->next().
1110 seq_hlist_next_percpu(void *v
, struct hlist_head __percpu
*head
,
1111 int *cpu
, loff_t
*pos
)
1113 struct hlist_node
*node
= v
;
1120 for (*cpu
= cpumask_next(*cpu
, cpu_possible_mask
); *cpu
< nr_cpu_ids
;
1121 *cpu
= cpumask_next(*cpu
, cpu_possible_mask
)) {
1122 struct hlist_head
*bucket
= per_cpu_ptr(head
, *cpu
);
1124 if (!hlist_empty(bucket
))
1125 return bucket
->first
;
1129 EXPORT_SYMBOL(seq_hlist_next_percpu
);
1131 void __init
seq_file_init(void)
1133 seq_file_cache
= KMEM_CACHE(seq_file
, SLAB_ACCOUNT
|SLAB_PANIC
);