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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/seq_file.c4 *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 ": " fmt10 11#include <linux/cache.h>12#include <linux/fs.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>18#include <linux/mm.h>19#include <linux/printk.h>20#include <linux/string_helpers.h>21#include <linux/uio.h>22 23#include <linux/uaccess.h>24#include <asm/page.h>25 26static struct kmem_cache *seq_file_cache __ro_after_init;27 28static void seq_set_overflow(struct seq_file *m)29{30 m->count = m->size;31}32 33static void *seq_buf_alloc(unsigned long size)34{35 if (unlikely(size > MAX_RW_COUNT))36 return NULL;37 38 return kvmalloc(size, GFP_KERNEL_ACCOUNT);39}40 41/**42 * seq_open - initialize sequential file43 * @file: file we initialize44 * @op: method table describing the sequence45 *46 * seq_open() sets @file, associating it with a sequence described47 * by @op. @op->start() sets the iterator up and returns the first48 * element of sequence. @op->stop() shuts it down. @op->next()49 * returns the next element of sequence. @op->show() prints element50 * into the buffer. In case of error ->start() and ->next() return51 * 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 its55 * pointer in @file->private_data. This pointer should not be modified.56 */57int seq_open(struct file *file, const struct seq_operations *op)58{59 struct seq_file *p;60 61 WARN_ON(file->private_data);62 63 p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL);64 if (!p)65 return -ENOMEM;66 67 file->private_data = p;68 69 mutex_init(&p->lock);70 p->op = op;71 72 // No refcounting: the lifetime of 'p' is constrained73 // to the lifetime of the file.74 p->file = file;75 76 /*77 * seq_files support lseek() and pread(). They do not implement78 * write() at all, but we clear FMODE_PWRITE here for historical79 * reasons.80 *81 * If a client of seq_files a) implements file.write() and b) wishes to82 * support pwrite() then that client will need to implement its own83 * file.open() which calls seq_open() and then sets FMODE_PWRITE.84 */85 file->f_mode &= ~FMODE_PWRITE;86 return 0;87}88EXPORT_SYMBOL(seq_open);89 90static int traverse(struct seq_file *m, loff_t offset)91{92 loff_t pos = 0;93 int error = 0;94 void *p;95 96 m->index = 0;97 m->count = m->from = 0;98 if (!offset)99 return 0;100 101 if (!m->buf) {102 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);103 if (!m->buf)104 return -ENOMEM;105 }106 p = m->op->start(m, &m->index);107 while (p) {108 error = PTR_ERR(p);109 if (IS_ERR(p))110 break;111 error = m->op->show(m, p);112 if (error < 0)113 break;114 if (unlikely(error)) {115 error = 0;116 m->count = 0;117 }118 if (seq_has_overflowed(m))119 goto Eoverflow;120 p = m->op->next(m, p, &m->index);121 if (pos + m->count > offset) {122 m->from = offset - pos;123 m->count -= m->from;124 break;125 }126 pos += m->count;127 m->count = 0;128 if (pos == offset)129 break;130 }131 m->op->stop(m, p);132 return error;133 134Eoverflow:135 m->op->stop(m, p);136 kvfree(m->buf);137 m->count = 0;138 m->buf = seq_buf_alloc(m->size <<= 1);139 return !m->buf ? -ENOMEM : -EAGAIN;140}141 142/**143 * seq_read - ->read() method for sequential files.144 * @file: the file to read from145 * @buf: the buffer to read to146 * @size: the maximum number of bytes to read147 * @ppos: the current position in the file148 *149 * Ready-made ->f_op->read()150 */151ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)152{153 struct iovec iov = { .iov_base = buf, .iov_len = size};154 struct kiocb kiocb;155 struct iov_iter iter;156 ssize_t ret;157 158 init_sync_kiocb(&kiocb, file);159 iov_iter_init(&iter, ITER_DEST, &iov, 1, size);160 161 kiocb.ki_pos = *ppos;162 ret = seq_read_iter(&kiocb, &iter);163 *ppos = kiocb.ki_pos;164 return ret;165}166EXPORT_SYMBOL(seq_read);167 168/*169 * Ready-made ->f_op->read_iter()170 */171ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)172{173 struct seq_file *m = iocb->ki_filp->private_data;174 size_t copied = 0;175 size_t n;176 void *p;177 int err = 0;178 179 if (!iov_iter_count(iter))180 return 0;181 182 mutex_lock(&m->lock);183 184 /*185 * if request is to read from zero offset, reset iterator to first186 * record as it might have been already advanced by previous requests187 */188 if (iocb->ki_pos == 0) {189 m->index = 0;190 m->count = 0;191 }192 193 /* 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)196 ;197 if (err) {198 /* With prejudice... */199 m->read_pos = 0;200 m->index = 0;201 m->count = 0;202 goto Done;203 } else {204 m->read_pos = iocb->ki_pos;205 }206 }207 208 /* grab buffer if we didn't have one */209 if (!m->buf) {210 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);211 if (!m->buf)212 goto Enomem;213 }214 // something left in the buffer - copy it out first215 if (m->count) {216 n = copy_to_iter(m->buf + m->from, m->count, iter);217 m->count -= n;218 m->from += n;219 copied += n;220 if (m->count) // hadn't managed to copy everything221 goto Done;222 }223 // get a non-empty record in the buffer224 m->from = 0;225 p = m->op->start(m, &m->index);226 while (1) {227 err = PTR_ERR(p);228 if (!p || IS_ERR(p)) // EOF or an error229 break;230 err = m->op->show(m, p);231 if (err < 0) // hard error232 break;233 if (unlikely(err)) // ->show() says "skip it"234 m->count = 0;235 if (unlikely(!m->count)) { // empty record236 p = m->op->next(m, p, &m->index);237 continue;238 }239 if (!seq_has_overflowed(m)) // got it240 goto Fill;241 // need a bigger buffer242 m->op->stop(m, p);243 kvfree(m->buf);244 m->count = 0;245 m->buf = seq_buf_alloc(m->size <<= 1);246 if (!m->buf)247 goto Enomem;248 p = m->op->start(m, &m->index);249 }250 // EOF or an error251 m->op->stop(m, p);252 m->count = 0;253 goto Done;254Fill: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 advance257 // the iterator once for every record shown.258 while (1) {259 size_t offs = m->count;260 loff_t pos = m->index;261 262 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",265 m->op->next);266 m->index++;267 }268 if (!p || IS_ERR(p)) // no next record for us269 break;270 if (m->count >= iov_iter_count(iter))271 break;272 err = m->op->show(m, p);273 if (err > 0) { // ->show() says "skip it"274 m->count = offs;275 } else if (err || seq_has_overflowed(m)) {276 m->count = offs;277 break;278 }279 }280 m->op->stop(m, p);281 n = copy_to_iter(m->buf, m->count, iter);282 copied += n;283 m->count -= n;284 m->from = n;285Done:286 if (unlikely(!copied)) {287 copied = m->count ? -EFAULT : err;288 } else {289 iocb->ki_pos += copied;290 m->read_pos += copied;291 }292 mutex_unlock(&m->lock);293 return copied;294Enomem:295 err = -ENOMEM;296 goto Done;297}298EXPORT_SYMBOL(seq_read_iter);299 300/**301 * seq_lseek - ->llseek() method for sequential files.302 * @file: the file in question303 * @offset: new position304 * @whence: 0 for absolute, 1 for relative position305 *306 * Ready-made ->f_op->llseek()307 */308loff_t seq_lseek(struct file *file, loff_t offset, int whence)309{310 struct seq_file *m = file->private_data;311 loff_t retval = -EINVAL;312 313 mutex_lock(&m->lock);314 switch (whence) {315 case SEEK_CUR:316 offset += file->f_pos;317 fallthrough;318 case SEEK_SET:319 if (offset < 0)320 break;321 retval = offset;322 if (offset != m->read_pos) {323 while ((retval = traverse(m, offset)) == -EAGAIN)324 ;325 if (retval) {326 /* with extreme prejudice... */327 file->f_pos = 0;328 m->read_pos = 0;329 m->index = 0;330 m->count = 0;331 } else {332 m->read_pos = offset;333 retval = file->f_pos = offset;334 }335 } else {336 file->f_pos = offset;337 }338 }339 mutex_unlock(&m->lock);340 return retval;341}342EXPORT_SYMBOL(seq_lseek);343 344/**345 * seq_release - free the structures associated with sequential file.346 * @file: file in question347 * @inode: its inode348 *349 * Frees the structures associated with sequential file; can be used350 * as ->f_op->release() if you don't have private data to destroy.351 */352int seq_release(struct inode *inode, struct file *file)353{354 struct seq_file *m = file->private_data;355 kvfree(m->buf);356 kmem_cache_free(seq_file_cache, m);357 return 0;358}359EXPORT_SYMBOL(seq_release);360 361/**362 * seq_escape_mem - print data into buffer, escaping some characters363 * @m: target buffer364 * @src: source buffer365 * @len: size of source buffer366 * @flags: flags to pass to string_escape_mem()367 * @esc: set of characters that need escaping368 *369 * Puts data into buffer, replacing each occurrence of character from370 * given class (defined by @flags and @esc) with printable escaped sequence.371 *372 * Use seq_has_overflowed() to check for errors.373 */374void seq_escape_mem(struct seq_file *m, const char *src, size_t len,375 unsigned int flags, const char *esc)376{377 char *buf;378 size_t size = seq_get_buf(m, &buf);379 int ret;380 381 ret = string_escape_mem(src, len, buf, size, flags, esc);382 seq_commit(m, ret < size ? ret : -1);383}384EXPORT_SYMBOL(seq_escape_mem);385 386void seq_vprintf(struct seq_file *m, const char *f, va_list args)387{388 int len;389 390 if (m->count < m->size) {391 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);392 if (m->count + len < m->size) {393 m->count += len;394 return;395 }396 }397 seq_set_overflow(m);398}399EXPORT_SYMBOL(seq_vprintf);400 401void seq_printf(struct seq_file *m, const char *f, ...)402{403 va_list args;404 405 va_start(args, f);406 seq_vprintf(m, f, args);407 va_end(args);408}409EXPORT_SYMBOL(seq_printf);410 411#ifdef CONFIG_BINARY_PRINTF412void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)413{414 int len;415 416 if (m->count < m->size) {417 len = bstr_printf(m->buf + m->count, m->size - m->count, f,418 binary);419 if (m->count + len < m->size) {420 m->count += len;421 return;422 }423 }424 seq_set_overflow(m);425}426EXPORT_SYMBOL(seq_bprintf);427#endif /* CONFIG_BINARY_PRINTF */428 429/**430 * mangle_path - mangle and copy path to buffer beginning431 * @s: buffer start432 * @p: beginning of path in above buffer433 * @esc: set of characters that need escaping434 *435 * Copy the path from @p to @s, replacing each occurrence of character from436 * @esc with usual octal escape.437 * Returns pointer past last written character in @s, or NULL in case of438 * failure.439 */440char *mangle_path(char *s, const char *p, const char *esc)441{442 while (s <= p) {443 char c = *p++;444 if (!c) {445 return s;446 } else if (!strchr(esc, c)) {447 *s++ = c;448 } else if (s + 4 > p) {449 break;450 } else {451 *s++ = '\\';452 *s++ = '0' + ((c & 0300) >> 6);453 *s++ = '0' + ((c & 070) >> 3);454 *s++ = '0' + (c & 07);455 }456 }457 return NULL;458}459EXPORT_SYMBOL(mangle_path);460 461/**462 * seq_path - seq_file interface to print a pathname463 * @m: the seq_file handle464 * @path: the struct path to print465 * @esc: set of characters to escape in the output466 *467 * return the absolute path of 'path', as represented by the468 * 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 = 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 file492 * @m: the seq_file handle493 * @file: the struct file to print494 * @esc: set of characters to escape in the output495 *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 = mangle_path(buf, p, esc);523 if (end)524 res = end - buf;525 else526 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 = 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(sizeof(*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 else587 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 numbers680 * without rich format of printf().681 * only 'unsigned long long' is supported.682 * @m: seq_file identifying the buffer to which data should be written683 * @delimiter: a string which is printed before the number684 * @num: the number685 * @width: a minimum field width686 *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 else703 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 notation732 * @m: seq_file identifying the buffer to which data should be written733 * @delimiter: a string which is printed before the number734 * @v: the number735 * @width: a minimum field width736 *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 else752 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 else759 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 else787 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 buffer817 * @seq: seq_file identifying the buffer to which data should be written818 * @data: data address819 * @len: number of bytes820 *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 buffer837 * @m: seq_file identifying the buffer to which data should be written838 * @c: the byte to append after padding if non-zero839 */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 hlist961 * @head: the head of the hlist962 * @pos: the start position of the sequence963 *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 hlist979 * @head: the head of the hlist980 * @pos: the start position of the sequence981 *982 * Called at seq_file->op->start(). Call this function if you want to983 * 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 hlist996 * @v: the current iterator997 * @head: the head of the hlist998 * @ppos: the current position999 *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 else1011 return node->next;1012}1013EXPORT_SYMBOL(seq_hlist_next);1014 1015/**1016 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU1017 * @head: the head of the hlist1018 * @pos: the start position of the sequence1019 *1020 * Called at seq_file->op->start().1021 *1022 * This list-traversal primitive may safely run concurrently with1023 * 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 RCU1040 * @head: the head of the hlist1041 * @pos: the start position of the sequence1042 *1043 * Called at seq_file->op->start(). Call this function if you want to1044 * print a header at the top of the output.1045 *1046 * This list-traversal primitive may safely run concurrently with1047 * 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 RCU1062 * @v: the current iterator1063 * @head: the head of the hlist1064 * @ppos: the current position1065 *1066 * Called at seq_file->op->next().1067 *1068 * This list-traversal primitive may safely run concurrently with1069 * 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 else1082 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 array1088 * @head: pointer to percpu array of struct hlist_heads1089 * @cpu: pointer to cpu "cursor"1090 * @pos: start position of sequence1091 *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 array1111 * @v: pointer to current hlist_node1112 * @head: pointer to percpu array of struct hlist_heads1113 * @cpu: pointer to cpu "cursor"1114 * @pos: start position of sequence1115 *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}1144