int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
{
	struct address_space *mapping = inode->i_mapping;
	struct page *page;
	void *fsdata;
	int err;
	unsigned int flags = 0;
	if (nofs)
		flags |= AOP_FLAG_NOFS;

retry:
	err = pagecache_write_begin(NULL, mapping, 0, len-1,
				flags, &page, &fsdata);
	if (err)
		goto fail;

	memcpy(page_address(page), symname, len-1);

	err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
							page, fsdata);
	if (err < 0)
		goto fail;
	if (err < len-1)
		goto retry;

	mark_inode_dirty(inode);
	return 0;
fail:
	return err;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.