#include <linux/slab.h>#include <linux/string.h>#include <linux/module.h>#include <linux/err.h>#include <asm/uaccess.h> /** * __kzalloc - allocate memory. The memory is set to zero. * @size: how many bytes of memory are required. * @flags: the type of memory to allocate. */void *__kzalloc(size_t size, gfp_t flags){	void *ret = ____kmalloc(size, flags);	if (ret)		memset(ret, 0, size);	return ret;}EXPORT_SYMBOL(__kzalloc); /* * kstrdup - allocate space for and copy an existing string * * @s: the string to duplicate * @gfp: the GFP mask used in the kmalloc() call when allocating memory */char *kstrdup(const char *s, gfp_t gfp){	size_t len;	char *buf; 	if (!s)		return NULL; 	len = strlen(s) + 1;	buf = ____kmalloc(len, gfp);	if (buf)		memcpy(buf, s, len);	return buf;}EXPORT_SYMBOL(kstrdup); /* * strndup_user - duplicate an existing string from user space * * @s: The string to duplicate * @n: Maximum number of bytes to copy, including the trailing NUL. */char *strndup_user(const char __user *s, long n){	char *p;	long length; 	length = strnlen_user(s, n); 	if (!length)		return ERR_PTR(-EFAULT); 	if (length > n)		return ERR_PTR(-EINVAL); 	p = kmalloc(length, GFP_KERNEL); 	if (!p)		return ERR_PTR(-ENOMEM); 	if (copy_from_user(p, s, length)) {		kfree(p);		return ERR_PTR(-EFAULT);	} 	p[length - 1] = '\0'; 	return p;}EXPORT_SYMBOL(strndup_user);