zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/fs/seq_file.c b/ap/os/linux/linux-3.4.x/fs/seq_file.c
new file mode 100644
index 0000000..0cbd049
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/seq_file.c
@@ -0,0 +1,891 @@
+/*
+ * linux/fs/seq_file.c
+ *
+ * helper functions for making synthetic files from sequences of records.
+ * initial implementation -- AV, Oct 2001.
+ */
+
+#include <linux/fs.h>
+#include <linux/export.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+
+#include <asm/uaccess.h>
+#include <asm/page.h>
+
+
+/*
+ * seq_files have a buffer which can may overflow. When this happens a larger
+ * buffer is reallocated and all the data will be printed again.
+ * The overflow state is true when m->count == m->size.
+ */
+static bool seq_overflow(struct seq_file *m)
+{
+ return m->count == m->size;
+}
+
+static void seq_set_overflow(struct seq_file *m)
+{
+ m->count = m->size;
+}
+
+/**
+ * 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".
+ */
+int seq_open(struct file *file, const struct seq_operations *op)
+{
+ struct seq_file *p = file->private_data;
+
+ if (!p) {
+ p = kmalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+ file->private_data = p;
+ }
+ memset(p, 0, sizeof(*p));
+ mutex_init(&p->lock);
+ p->op = op;
+
+ /*
+ * Wrappers around seq_open(e.g. swaps_open) need to be
+ * aware of this. If they set f_version themselves, they
+ * should call seq_open first and then set f_version.
+ */
+ file->f_version = 0;
+
+ /*
+ * 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, index;
+ int error = 0;
+ void *p;
+
+ m->version = 0;
+ index = 0;
+ m->count = m->from = 0;
+ if (!offset) {
+ m->index = index;
+ return 0;
+ }
+ if (!m->buf) {
+ m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
+ if (!m->buf)
+ return -ENOMEM;
+ }
+ p = m->op->start(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_overflow(m))
+ goto Eoverflow;
+ if (pos + m->count > offset) {
+ m->from = offset - pos;
+ m->count -= m->from;
+ m->index = index;
+ break;
+ }
+ pos += m->count;
+ m->count = 0;
+ if (pos == offset) {
+ index++;
+ m->index = index;
+ break;
+ }
+ p = m->op->next(m, p, &index);
+ }
+ m->op->stop(m, p);
+ m->index = index;
+ return error;
+
+Eoverflow:
+ m->op->stop(m, p);
+ kfree(m->buf);
+ m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
+ 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 seq_file *m = file->private_data;
+ size_t copied = 0;
+ loff_t pos;
+ size_t n;
+ void *p;
+ int err = 0;
+
+ mutex_lock(&m->lock);
+
+ /*
+ * seq_file->op->..m_start/m_stop/m_next may do special actions
+ * or optimisations based on the file->f_version, so we want to
+ * pass the file->f_version to those methods.
+ *
+ * seq_file->version is just copy of f_version, and seq_file
+ * methods can treat it simply as file version.
+ * It is copied in first and copied out after all operations.
+ * It is convenient to have it as part of structure to avoid the
+ * need of passing another argument to all the seq_file methods.
+ */
+ m->version = file->f_version;
+
+ /* Don't assume *ppos is where we left it */
+ if (unlikely(*ppos != m->read_pos)) {
+ while ((err = traverse(m, *ppos)) == -EAGAIN)
+ ;
+ if (err) {
+ /* With prejudice... */
+ m->read_pos = 0;
+ m->version = 0;
+ m->index = 0;
+ m->count = 0;
+ goto Done;
+ } else {
+ m->read_pos = *ppos;
+ }
+ }
+
+ /* grab buffer if we didn't have one */
+ if (!m->buf) {
+ m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
+ if (!m->buf)
+ goto Enomem;
+ }
+ /* if not empty - flush it first */
+ if (m->count) {
+ n = min(m->count, size);
+ err = copy_to_user(buf, m->buf + m->from, n);
+ if (err)
+ goto Efault;
+ m->count -= n;
+ m->from += n;
+ size -= n;
+ buf += n;
+ copied += n;
+ if (!m->count)
+ m->index++;
+ if (!size)
+ goto Done;
+ }
+ /* we need at least one record in buffer */
+ pos = m->index;
+ p = m->op->start(m, &pos);
+ while (1) {
+ err = PTR_ERR(p);
+ if (!p || IS_ERR(p))
+ break;
+ err = m->op->show(m, p);
+ if (err < 0)
+ break;
+ if (unlikely(err))
+ m->count = 0;
+ if (unlikely(!m->count)) {
+ p = m->op->next(m, p, &pos);
+ m->index = pos;
+ continue;
+ }
+ if (m->count < m->size)
+ goto Fill;
+ m->op->stop(m, p);
+ kfree(m->buf);
+ m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
+ if (!m->buf)
+ goto Enomem;
+ m->count = 0;
+ m->version = 0;
+ pos = m->index;
+ p = m->op->start(m, &pos);
+ }
+ m->op->stop(m, p);
+ m->count = 0;
+ goto Done;
+Fill:
+ /* they want more? let's try to get some more */
+ while (m->count < size) {
+ size_t offs = m->count;
+ loff_t next = pos;
+ p = m->op->next(m, p, &next);
+ if (!p || IS_ERR(p)) {
+ err = PTR_ERR(p);
+ break;
+ }
+ err = m->op->show(m, p);
+ if (seq_overflow(m) || err) {
+ m->count = offs;
+ if (likely(err <= 0))
+ break;
+ }
+ pos = next;
+ }
+ m->op->stop(m, p);
+ n = min(m->count, size);
+ err = copy_to_user(buf, m->buf, n);
+ if (err)
+ goto Efault;
+ copied += n;
+ m->count -= n;
+ if (m->count)
+ m->from = n;
+ else
+ pos++;
+ m->index = pos;
+Done:
+ if (!copied)
+ copied = err;
+ else {
+ *ppos += copied;
+ m->read_pos += copied;
+ }
+ file->f_version = m->version;
+ mutex_unlock(&m->lock);
+ return copied;
+Enomem:
+ err = -ENOMEM;
+ goto Done;
+Efault:
+ err = -EFAULT;
+ goto Done;
+}
+EXPORT_SYMBOL(seq_read);
+
+/**
+ * seq_lseek - ->llseek() method for sequential files.
+ * @file: the file in question
+ * @offset: new position
+ * @origin: 0 for absolute, 1 for relative position
+ *
+ * Ready-made ->f_op->llseek()
+ */
+loff_t seq_lseek(struct file *file, loff_t offset, int origin)
+{
+ struct seq_file *m = file->private_data;
+ loff_t retval = -EINVAL;
+
+ mutex_lock(&m->lock);
+ m->version = file->f_version;
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ 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->version = 0;
+ m->index = 0;
+ m->count = 0;
+ } else {
+ m->read_pos = offset;
+ retval = file->f_pos = offset;
+ }
+ }
+ }
+ file->f_version = m->version;
+ mutex_unlock(&m->lock);
+ return retval;
+}
+EXPORT_SYMBOL(seq_lseek);
+
+/**
+ * seq_release - free the structures associated with sequential file.
+ * @file: file in question
+ * @inode: file->f_path.dentry->d_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;
+ kfree(m->buf);
+ kfree(m);
+ return 0;
+}
+EXPORT_SYMBOL(seq_release);
+
+/**
+ * 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. Returns 0 in case of success, -1 - in
+ * case of overflow.
+ */
+int seq_escape(struct seq_file *m, const char *s, const char *esc)
+{
+ char *end = m->buf + m->size;
+ char *p;
+ char c;
+
+ for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
+ if (!strchr(esc, c)) {
+ *p++ = c;
+ continue;
+ }
+ if (p + 3 < end) {
+ *p++ = '\\';
+ *p++ = '0' + ((c & 0300) >> 6);
+ *p++ = '0' + ((c & 070) >> 3);
+ *p++ = '0' + (c & 07);
+ continue;
+ }
+ seq_set_overflow(m);
+ return -1;
+ }
+ m->count = p - m->buf;
+ return 0;
+}
+EXPORT_SYMBOL(seq_escape);
+
+int seq_printf(struct seq_file *m, const char *f, ...)
+{
+ va_list args;
+ int len;
+
+ if (m->count < m->size) {
+ va_start(args, f);
+ len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
+ va_end(args);
+ if (m->count + len < m->size) {
+ m->count += len;
+ return 0;
+ }
+ }
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_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);
+
+/*
+ * 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;
+}
+
+int seq_bitmap(struct seq_file *m, const unsigned long *bits,
+ unsigned int nr_bits)
+{
+ if (m->count < m->size) {
+ int len = bitmap_scnprintf(m->buf + m->count,
+ m->size - m->count, bits, nr_bits);
+ if (m->count + len < m->size) {
+ m->count += len;
+ return 0;
+ }
+ }
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_bitmap);
+
+int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
+ unsigned int nr_bits)
+{
+ if (m->count < m->size) {
+ int len = bitmap_scnlistprintf(m->buf + m->count,
+ m->size - m->count, bits, nr_bits);
+ if (m->count + len < m->size) {
+ m->count += len;
+ return 0;
+ }
+ }
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_bitmap_list);
+
+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);
+ 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_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);
+ 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);
+
+int seq_putc(struct seq_file *m, char c)
+{
+ if (m->count < m->size) {
+ m->buf[m->count++] = c;
+ return 0;
+ }
+ return -1;
+}
+EXPORT_SYMBOL(seq_putc);
+
+int seq_puts(struct seq_file *m, const char *s)
+{
+ int len = strlen(s);
+ if (m->count + len < m->size) {
+ memcpy(m->buf + m->count, s, len);
+ m->count += len;
+ return 0;
+ }
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_puts);
+
+/*
+ * A helper routine for putting decimal numbers without rich format of printf().
+ * only 'unsigned long long' is supported.
+ * This routine will put one byte delimiter + number into seq_file.
+ * 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.
+ */
+int seq_put_decimal_ull(struct seq_file *m, char delimiter,
+ unsigned long long num)
+{
+ int len;
+
+ if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
+ goto overflow;
+
+ if (delimiter)
+ m->buf[m->count++] = delimiter;
+
+ if (num < 10) {
+ m->buf[m->count++] = num + '0';
+ return 0;
+ }
+
+ len = num_to_str(m->buf + m->count, m->size - m->count, num);
+ if (!len)
+ goto overflow;
+ m->count += len;
+ return 0;
+overflow:
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_put_decimal_ull);
+
+int seq_put_decimal_ll(struct seq_file *m, char delimiter,
+ long long num)
+{
+ if (num < 0) {
+ if (m->count + 3 >= m->size) {
+ seq_set_overflow(m);
+ return -1;
+ }
+ if (delimiter)
+ m->buf[m->count++] = delimiter;
+ num = -num;
+ delimiter = '-';
+ }
+ return seq_put_decimal_ull(m, delimiter, num);
+
+}
+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);
+
+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);