linux-stable/fs/seq_file.c
Eric Sandeen 8cae8cd89f seq_file: disallow extremely large seq buffer allocations
There is no reasonable need for a buffer larger than this, and it avoids
int overflow pitfalls.

Fixes: 058504edd0 ("fs/seq_file: fallback to vmalloc allocation")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-19 17:18:48 -07:00

1134 lines
26 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/seq_file.c
*
* helper functions for making synthetic files from sequences of records.
* initial implementation -- AV, Oct 2001.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cache.h>
#include <linux/fs.h>
#include <linux/export.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/string_helpers.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <asm/page.h>
static struct kmem_cache *seq_file_cache __ro_after_init;
static void seq_set_overflow(struct seq_file *m)
{
m->count = m->size;
}
static void *seq_buf_alloc(unsigned long size)
{
if (unlikely(size > MAX_RW_COUNT))
return NULL;
return kvmalloc(size, GFP_KERNEL_ACCOUNT);
}
/**
* seq_open - initialize sequential file
* @file: file we initialize
* @op: method table describing the sequence
*
* seq_open() sets @file, associating it with a sequence described
* by @op. @op->start() sets the iterator up and returns the first
* element of sequence. @op->stop() shuts it down. @op->next()
* returns the next element of sequence. @op->show() prints element
* into the buffer. In case of error ->start() and ->next() return
* ERR_PTR(error). In the end of sequence they return %NULL. ->show()
* returns 0 in case of success and negative number in case of error.
* Returning SEQ_SKIP means "discard this element and move on".
* Note: seq_open() will allocate a struct seq_file and store its
* pointer in @file->private_data. This pointer should not be modified.
*/
int seq_open(struct file *file, const struct seq_operations *op)
{
struct seq_file *p;
WARN_ON(file->private_data);
p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL);
if (!p)
return -ENOMEM;
file->private_data = p;
mutex_init(&p->lock);
p->op = op;
// No refcounting: the lifetime of 'p' is constrained
// to the lifetime of the file.
p->file = file;
/*
* seq_files support lseek() and pread(). They do not implement
* write() at all, but we clear FMODE_PWRITE here for historical
* reasons.
*
* If a client of seq_files a) implements file.write() and b) wishes to
* support pwrite() then that client will need to implement its own
* file.open() which calls seq_open() and then sets FMODE_PWRITE.
*/
file->f_mode &= ~FMODE_PWRITE;
return 0;
}
EXPORT_SYMBOL(seq_open);
static int traverse(struct seq_file *m, loff_t offset)
{
loff_t pos = 0;
int error = 0;
void *p;
m->index = 0;
m->count = m->from = 0;
if (!offset)
return 0;
if (!m->buf) {
m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
if (!m->buf)
return -ENOMEM;
}
p = m->op->start(m, &m->index);
while (p) {
error = PTR_ERR(p);
if (IS_ERR(p))
break;
error = m->op->show(m, p);
if (error < 0)
break;
if (unlikely(error)) {
error = 0;
m->count = 0;
}
if (seq_has_overflowed(m))
goto Eoverflow;
p = m->op->next(m, p, &m->index);
if (pos + m->count > offset) {
m->from = offset - pos;
m->count -= m->from;
break;
}
pos += m->count;
m->count = 0;
if (pos == offset)
break;
}
m->op->stop(m, p);
return error;
Eoverflow:
m->op->stop(m, p);
kvfree(m->buf);
m->count = 0;
m->buf = seq_buf_alloc(m->size <<= 1);
return !m->buf ? -ENOMEM : -EAGAIN;
}
/**
* seq_read - ->read() method for sequential files.
* @file: the file to read from
* @buf: the buffer to read to
* @size: the maximum number of bytes to read
* @ppos: the current position in the file
*
* Ready-made ->f_op->read()
*/
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
struct iovec iov = { .iov_base = buf, .iov_len = size};
struct kiocb kiocb;
struct iov_iter iter;
ssize_t ret;
init_sync_kiocb(&kiocb, file);
iov_iter_init(&iter, READ, &iov, 1, size);
kiocb.ki_pos = *ppos;
ret = seq_read_iter(&kiocb, &iter);
*ppos = kiocb.ki_pos;
return ret;
}
EXPORT_SYMBOL(seq_read);
/*
* Ready-made ->f_op->read_iter()
*/
ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct seq_file *m = iocb->ki_filp->private_data;
size_t copied = 0;
size_t n;
void *p;
int err = 0;
if (!iov_iter_count(iter))
return 0;
mutex_lock(&m->lock);
/*
* if request is to read from zero offset, reset iterator to first
* record as it might have been already advanced by previous requests
*/
if (iocb->ki_pos == 0) {
m->index = 0;
m->count = 0;
}
/* Don't assume ki_pos is where we left it */
if (unlikely(iocb->ki_pos != m->read_pos)) {
while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN)
;
if (err) {
/* With prejudice... */
m->read_pos = 0;
m->index = 0;
m->count = 0;
goto Done;
} else {
m->read_pos = iocb->ki_pos;
}
}
/* grab buffer if we didn't have one */
if (!m->buf) {
m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
if (!m->buf)
goto Enomem;
}
// something left in the buffer - copy it out first
if (m->count) {
n = copy_to_iter(m->buf + m->from, m->count, iter);
m->count -= n;
m->from += n;
copied += n;
if (m->count) // hadn't managed to copy everything
goto Done;
}
// get a non-empty record in the buffer
m->from = 0;
p = m->op->start(m, &m->index);
while (1) {
err = PTR_ERR(p);
if (!p || IS_ERR(p)) // EOF or an error
break;
err = m->op->show(m, p);
if (err < 0) // hard error
break;
if (unlikely(err)) // ->show() says "skip it"
m->count = 0;
if (unlikely(!m->count)) { // empty record
p = m->op->next(m, p, &m->index);
continue;
}
if (!seq_has_overflowed(m)) // got it
goto Fill;
// need a bigger buffer
m->op->stop(m, p);
kvfree(m->buf);
m->count = 0;
m->buf = seq_buf_alloc(m->size <<= 1);
if (!m->buf)
goto Enomem;
p = m->op->start(m, &m->index);
}
// EOF or an error
m->op->stop(m, p);
m->count = 0;
goto Done;
Fill:
// one non-empty record is in the buffer; if they want more,
// try to fit more in, but in any case we need to advance
// the iterator once for every record shown.
while (1) {
size_t offs = m->count;
loff_t pos = m->index;
p = m->op->next(m, p, &m->index);
if (pos == m->index) {
pr_info_ratelimited("buggy .next function %ps did not update position index\n",
m->op->next);
m->index++;
}
if (!p || IS_ERR(p)) // no next record for us
break;
if (m->count >= iov_iter_count(iter))
break;
err = m->op->show(m, p);
if (err > 0) { // ->show() says "skip it"
m->count = offs;
} else if (err || seq_has_overflowed(m)) {
m->count = offs;
break;
}
}
m->op->stop(m, p);
n = copy_to_iter(m->buf, m->count, iter);
copied += n;
m->count -= n;
m->from = n;
Done:
if (unlikely(!copied)) {
copied = m->count ? -EFAULT : err;
} else {
iocb->ki_pos += copied;
m->read_pos += copied;
}
mutex_unlock(&m->lock);
return copied;
Enomem:
err = -ENOMEM;
goto Done;
}
EXPORT_SYMBOL(seq_read_iter);
/**
* seq_lseek - ->llseek() method for sequential files.
* @file: the file in question
* @offset: new position
* @whence: 0 for absolute, 1 for relative position
*
* Ready-made ->f_op->llseek()
*/
loff_t seq_lseek(struct file *file, loff_t offset, int whence)
{
struct seq_file *m = file->private_data;
loff_t retval = -EINVAL;
mutex_lock(&m->lock);
switch (whence) {
case SEEK_CUR:
offset += file->f_pos;
fallthrough;
case SEEK_SET:
if (offset < 0)
break;
retval = offset;
if (offset != m->read_pos) {
while ((retval = traverse(m, offset)) == -EAGAIN)
;
if (retval) {
/* with extreme prejudice... */
file->f_pos = 0;
m->read_pos = 0;
m->index = 0;
m->count = 0;
} else {
m->read_pos = offset;
retval = file->f_pos = offset;
}
} else {
file->f_pos = offset;
}
}
mutex_unlock(&m->lock);
return retval;
}
EXPORT_SYMBOL(seq_lseek);
/**
* seq_release - free the structures associated with sequential file.
* @file: file in question
* @inode: its inode
*
* Frees the structures associated with sequential file; can be used
* as ->f_op->release() if you don't have private data to destroy.
*/
int seq_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
kvfree(m->buf);
kmem_cache_free(seq_file_cache, m);
return 0;
}
EXPORT_SYMBOL(seq_release);
/**
* seq_escape_mem - print data into buffer, escaping some characters
* @m: target buffer
* @src: source buffer
* @len: size of source buffer
* @flags: flags to pass to string_escape_mem()
* @esc: set of characters that need escaping
*
* Puts data into buffer, replacing each occurrence of character from
* given class (defined by @flags and @esc) with printable escaped sequence.
*
* Use seq_has_overflowed() to check for errors.
*/
void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
unsigned int flags, const char *esc)
{
char *buf;
size_t size = seq_get_buf(m, &buf);
int ret;
ret = string_escape_mem(src, len, buf, size, flags, esc);
seq_commit(m, ret < size ? ret : -1);
}
EXPORT_SYMBOL(seq_escape_mem);
/**
* seq_escape - print string into buffer, escaping some characters
* @m: target buffer
* @s: string
* @esc: set of characters that need escaping
*
* Puts string into buffer, replacing each occurrence of character from
* @esc with usual octal escape.
* Use seq_has_overflowed() to check for errors.
*/
void seq_escape(struct seq_file *m, const char *s, const char *esc)
{
seq_escape_str(m, s, ESCAPE_OCTAL, esc);
}
EXPORT_SYMBOL(seq_escape);
void seq_vprintf(struct seq_file *m, const char *f, va_list args)
{
int len;
if (m->count < m->size) {
len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
if (m->count + len < m->size) {
m->count += len;
return;
}
}
seq_set_overflow(m);
}
EXPORT_SYMBOL(seq_vprintf);
void seq_printf(struct seq_file *m, const char *f, ...)
{
va_list args;
va_start(args, f);
seq_vprintf(m, f, args);
va_end(args);
}
EXPORT_SYMBOL(seq_printf);
#ifdef CONFIG_BINARY_PRINTF
void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
{
int len;
if (m->count < m->size) {
len = bstr_printf(m->buf + m->count, m->size - m->count, f,
binary);
if (m->count + len < m->size) {
m->count += len;
return;
}
}
seq_set_overflow(m);
}
EXPORT_SYMBOL(seq_bprintf);
#endif /* CONFIG_BINARY_PRINTF */
/**
* mangle_path - mangle and copy path to buffer beginning
* @s: buffer start
* @p: beginning of path in above buffer
* @esc: set of characters that need escaping
*
* Copy the path from @p to @s, replacing each occurrence of character from
* @esc with usual octal escape.
* Returns pointer past last written character in @s, or NULL in case of
* failure.
*/
char *mangle_path(char *s, const char *p, const char *esc)
{
while (s <= p) {
char c = *p++;
if (!c) {
return s;
} else if (!strchr(esc, c)) {
*s++ = c;
} else if (s + 4 > p) {
break;
} else {
*s++ = '\\';
*s++ = '0' + ((c & 0300) >> 6);
*s++ = '0' + ((c & 070) >> 3);
*s++ = '0' + (c & 07);
}
}
return NULL;
}
EXPORT_SYMBOL(mangle_path);
/**
* seq_path - seq_file interface to print a pathname
* @m: the seq_file handle
* @path: the struct path to print
* @esc: set of characters to escape in the output
*
* return the absolute path of 'path', as represented by the
* dentry / mnt pair in the path parameter.
*/
int seq_path(struct seq_file *m, const struct path *path, const char *esc)
{
char *buf;
size_t size = seq_get_buf(m, &buf);
int res = -1;
if (size) {
char *p = d_path(path, buf, size);
if (!IS_ERR(p)) {
char *end = mangle_path(buf, p, esc);
if (end)
res = end - buf;
}
}
seq_commit(m, res);
return res;
}
EXPORT_SYMBOL(seq_path);
/**
* seq_file_path - seq_file interface to print a pathname of a file
* @m: the seq_file handle
* @file: the struct file to print
* @esc: set of characters to escape in the output
*
* return the absolute path to the file.
*/
int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
{
return seq_path(m, &file->f_path, esc);
}
EXPORT_SYMBOL(seq_file_path);
/*
* Same as seq_path, but relative to supplied root.
*/
int seq_path_root(struct seq_file *m, const struct path *path,
const struct path *root, const char *esc)
{
char *buf;
size_t size = seq_get_buf(m, &buf);
int res = -ENAMETOOLONG;
if (size) {
char *p;
p = __d_path(path, root, buf, size);
if (!p)
return SEQ_SKIP;
res = PTR_ERR(p);
if (!IS_ERR(p)) {
char *end = mangle_path(buf, p, esc);
if (end)
res = end - buf;
else
res = -ENAMETOOLONG;
}
}
seq_commit(m, res);
return res < 0 && res != -ENAMETOOLONG ? res : 0;
}
/*
* returns the path of the 'dentry' from the root of its filesystem.
*/
int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
{
char *buf;
size_t size = seq_get_buf(m, &buf);
int res = -1;
if (size) {
char *p = dentry_path(dentry, buf, size);
if (!IS_ERR(p)) {
char *end = mangle_path(buf, p, esc);
if (end)
res = end - buf;
}
}
seq_commit(m, res);
return res;
}
EXPORT_SYMBOL(seq_dentry);
static void *single_start(struct seq_file *p, loff_t *pos)
{
return NULL + (*pos == 0);
}
static void *single_next(struct seq_file *p, void *v, loff_t *pos)
{
++*pos;
return NULL;
}
static void single_stop(struct seq_file *p, void *v)
{
}
int single_open(struct file *file, int (*show)(struct seq_file *, void *),
void *data)
{
struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT);
int res = -ENOMEM;
if (op) {
op->start = single_start;
op->next = single_next;
op->stop = single_stop;
op->show = show;
res = seq_open(file, op);
if (!res)
((struct seq_file *)file->private_data)->private = data;
else
kfree(op);
}
return res;
}
EXPORT_SYMBOL(single_open);
int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
void *data, size_t size)
{
char *buf = seq_buf_alloc(size);
int ret;
if (!buf)
return -ENOMEM;
ret = single_open(file, show, data);
if (ret) {
kvfree(buf);
return ret;
}
((struct seq_file *)file->private_data)->buf = buf;
((struct seq_file *)file->private_data)->size = size;
return 0;
}
EXPORT_SYMBOL(single_open_size);
int single_release(struct inode *inode, struct file *file)
{
const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
int res = seq_release(inode, file);
kfree(op);
return res;
}
EXPORT_SYMBOL(single_release);
int seq_release_private(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
kfree(seq->private);
seq->private = NULL;
return seq_release(inode, file);
}
EXPORT_SYMBOL(seq_release_private);
void *__seq_open_private(struct file *f, const struct seq_operations *ops,
int psize)
{
int rc;
void *private;
struct seq_file *seq;
private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
if (private == NULL)
goto out;
rc = seq_open(f, ops);
if (rc < 0)
goto out_free;
seq = f->private_data;
seq->private = private;
return private;
out_free:
kfree(private);
out:
return NULL;
}
EXPORT_SYMBOL(__seq_open_private);
int seq_open_private(struct file *filp, const struct seq_operations *ops,
int psize)
{
return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(seq_open_private);
void seq_putc(struct seq_file *m, char c)
{
if (m->count >= m->size)
return;
m->buf[m->count++] = c;
}
EXPORT_SYMBOL(seq_putc);
void seq_puts(struct seq_file *m, const char *s)
{
int len = strlen(s);
if (m->count + len >= m->size) {
seq_set_overflow(m);
return;
}
memcpy(m->buf + m->count, s, len);
m->count += len;
}
EXPORT_SYMBOL(seq_puts);
/**
* seq_put_decimal_ull_width - A helper routine for putting decimal numbers
* without rich format of printf().
* only 'unsigned long long' is supported.
* @m: seq_file identifying the buffer to which data should be written
* @delimiter: a string which is printed before the number
* @num: the number
* @width: a minimum field width
*
* This routine will put strlen(delimiter) + number into seq_filed.
* This routine is very quick when you show lots of numbers.
* In usual cases, it will be better to use seq_printf(). It's easier to read.
*/
void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
unsigned long long num, unsigned int width)
{
int len;
if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
goto overflow;
if (delimiter && delimiter[0]) {
if (delimiter[1] == 0)
seq_putc(m, delimiter[0]);
else
seq_puts(m, delimiter);
}
if (!width)
width = 1;
if (m->count + width >= m->size)
goto overflow;
len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
if (!len)
goto overflow;
m->count += len;
return;
overflow:
seq_set_overflow(m);
}
void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
unsigned long long num)
{
return seq_put_decimal_ull_width(m, delimiter, num, 0);
}
EXPORT_SYMBOL(seq_put_decimal_ull);
/**
* seq_put_hex_ll - put a number in hexadecimal notation
* @m: seq_file identifying the buffer to which data should be written
* @delimiter: a string which is printed before the number
* @v: the number
* @width: a minimum field width
*
* seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
*
* This routine is very quick when you show lots of numbers.
* In usual cases, it will be better to use seq_printf(). It's easier to read.
*/
void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
unsigned long long v, unsigned int width)
{
unsigned int len;
int i;
if (delimiter && delimiter[0]) {
if (delimiter[1] == 0)
seq_putc(m, delimiter[0]);
else
seq_puts(m, delimiter);
}
/* If x is 0, the result of __builtin_clzll is undefined */
if (v == 0)
len = 1;
else
len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
if (len < width)
len = width;
if (m->count + len > m->size) {
seq_set_overflow(m);
return;
}
for (i = len - 1; i >= 0; i--) {
m->buf[m->count + i] = hex_asc[0xf & v];
v = v >> 4;
}
m->count += len;
}
void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
{
int len;
if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
goto overflow;
if (delimiter && delimiter[0]) {
if (delimiter[1] == 0)
seq_putc(m, delimiter[0]);
else
seq_puts(m, delimiter);
}
if (m->count + 2 >= m->size)
goto overflow;
if (num < 0) {
m->buf[m->count++] = '-';
num = -num;
}
if (num < 10) {
m->buf[m->count++] = num + '0';
return;
}
len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
if (!len)
goto overflow;
m->count += len;
return;
overflow:
seq_set_overflow(m);
}
EXPORT_SYMBOL(seq_put_decimal_ll);
/**
* seq_write - write arbitrary data to buffer
* @seq: seq_file identifying the buffer to which data should be written
* @data: data address
* @len: number of bytes
*
* Return 0 on success, non-zero otherwise.
*/
int seq_write(struct seq_file *seq, const void *data, size_t len)
{
if (seq->count + len < seq->size) {
memcpy(seq->buf + seq->count, data, len);
seq->count += len;
return 0;
}
seq_set_overflow(seq);
return -1;
}
EXPORT_SYMBOL(seq_write);
/**
* seq_pad - write padding spaces to buffer
* @m: seq_file identifying the buffer to which data should be written
* @c: the byte to append after padding if non-zero
*/
void seq_pad(struct seq_file *m, char c)
{
int size = m->pad_until - m->count;
if (size > 0) {
if (size + m->count > m->size) {
seq_set_overflow(m);
return;
}
memset(m->buf + m->count, ' ', size);
m->count += size;
}
if (c)
seq_putc(m, c);
}
EXPORT_SYMBOL(seq_pad);
/* A complete analogue of print_hex_dump() */
void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
int rowsize, int groupsize, const void *buf, size_t len,
bool ascii)
{
const u8 *ptr = buf;
int i, linelen, remaining = len;
char *buffer;
size_t size;
int ret;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
switch (prefix_type) {
case DUMP_PREFIX_ADDRESS:
seq_printf(m, "%s%p: ", prefix_str, ptr + i);
break;
case DUMP_PREFIX_OFFSET:
seq_printf(m, "%s%.8x: ", prefix_str, i);
break;
default:
seq_printf(m, "%s", prefix_str);
break;
}
size = seq_get_buf(m, &buffer);
ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
buffer, size, ascii);
seq_commit(m, ret < size ? ret : -1);
seq_putc(m, '\n');
}
}
EXPORT_SYMBOL(seq_hex_dump);
struct list_head *seq_list_start(struct list_head *head, loff_t pos)
{
struct list_head *lh;
list_for_each(lh, head)
if (pos-- == 0)
return lh;
return NULL;
}
EXPORT_SYMBOL(seq_list_start);
struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
{
if (!pos)
return head;
return seq_list_start(head, pos - 1);
}
EXPORT_SYMBOL(seq_list_start_head);
struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
{
struct list_head *lh;
lh = ((struct list_head *)v)->next;
++*ppos;
return lh == head ? NULL : lh;
}
EXPORT_SYMBOL(seq_list_next);
/**
* seq_hlist_start - start an iteration of a hlist
* @head: the head of the hlist
* @pos: the start position of the sequence
*
* Called at seq_file->op->start().
*/
struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
{
struct hlist_node *node;
hlist_for_each(node, head)
if (pos-- == 0)
return node;
return NULL;
}
EXPORT_SYMBOL(seq_hlist_start);
/**
* seq_hlist_start_head - start an iteration of a hlist
* @head: the head of the hlist
* @pos: the start position of the sequence
*
* Called at seq_file->op->start(). Call this function if you want to
* print a header at the top of the output.
*/
struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
{
if (!pos)
return SEQ_START_TOKEN;
return seq_hlist_start(head, pos - 1);
}
EXPORT_SYMBOL(seq_hlist_start_head);
/**
* seq_hlist_next - move to the next position of the hlist
* @v: the current iterator
* @head: the head of the hlist
* @ppos: the current position
*
* Called at seq_file->op->next().
*/
struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
loff_t *ppos)
{
struct hlist_node *node = v;
++*ppos;
if (v == SEQ_START_TOKEN)
return head->first;
else
return node->next;
}
EXPORT_SYMBOL(seq_hlist_next);
/**
* seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
* @head: the head of the hlist
* @pos: the start position of the sequence
*
* Called at seq_file->op->start().
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as hlist_add_head_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
loff_t pos)
{
struct hlist_node *node;
__hlist_for_each_rcu(node, head)
if (pos-- == 0)
return node;
return NULL;
}
EXPORT_SYMBOL(seq_hlist_start_rcu);
/**
* seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
* @head: the head of the hlist
* @pos: the start position of the sequence
*
* Called at seq_file->op->start(). Call this function if you want to
* print a header at the top of the output.
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as hlist_add_head_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
loff_t pos)
{
if (!pos)
return SEQ_START_TOKEN;
return seq_hlist_start_rcu(head, pos - 1);
}
EXPORT_SYMBOL(seq_hlist_start_head_rcu);
/**
* seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
* @v: the current iterator
* @head: the head of the hlist
* @ppos: the current position
*
* Called at seq_file->op->next().
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as hlist_add_head_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
struct hlist_node *seq_hlist_next_rcu(void *v,
struct hlist_head *head,
loff_t *ppos)
{
struct hlist_node *node = v;
++*ppos;
if (v == SEQ_START_TOKEN)
return rcu_dereference(head->first);
else
return rcu_dereference(node->next);
}
EXPORT_SYMBOL(seq_hlist_next_rcu);
/**
* seq_hlist_start_percpu - start an iteration of a percpu hlist array
* @head: pointer to percpu array of struct hlist_heads
* @cpu: pointer to cpu "cursor"
* @pos: start position of sequence
*
* Called at seq_file->op->start().
*/
struct hlist_node *
seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
{
struct hlist_node *node;
for_each_possible_cpu(*cpu) {
hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
if (pos-- == 0)
return node;
}
}
return NULL;
}
EXPORT_SYMBOL(seq_hlist_start_percpu);
/**
* seq_hlist_next_percpu - move to the next position of the percpu hlist array
* @v: pointer to current hlist_node
* @head: pointer to percpu array of struct hlist_heads
* @cpu: pointer to cpu "cursor"
* @pos: start position of sequence
*
* Called at seq_file->op->next().
*/
struct hlist_node *
seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
int *cpu, loff_t *pos)
{
struct hlist_node *node = v;
++*pos;
if (node->next)
return node->next;
for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
*cpu = cpumask_next(*cpu, cpu_possible_mask)) {
struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
if (!hlist_empty(bucket))
return bucket->first;
}
return NULL;
}
EXPORT_SYMBOL(seq_hlist_next_percpu);
void __init seq_file_init(void)
{
seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
}