/* * custom_method.c - debugfs interface for customizing ACPI control method */ #include <linux/init.h>#include <linux/module.h>#include <linux/kernel.h>#include <linux/uaccess.h>#include <linux/debugfs.h>#include <linux/acpi.h> #include "internal.h" #define _COMPONENT		ACPI_SYSTEM_COMPONENTACPI_MODULE_NAME("custom_method");MODULE_LICENSE("GPL"); static struct dentry *cm_dentry; /* /sys/kernel/debug/acpi/custom_method */ static ssize_t cm_write(struct file *file, const char __user * user_buf,			size_t count, loff_t *ppos){	static char *buf;	static u32 max_size;	static u32 uncopied_bytes; 	struct acpi_table_header table;	acpi_status status; 	if (!(*ppos)) {		/* parse the table header to get the table length */		if (count <= sizeof(struct acpi_table_header))			return -EINVAL;		if (copy_from_user(&table, user_buf,				   sizeof(struct acpi_table_header)))			return -EFAULT;		uncopied_bytes = max_size = table.length;		buf = kzalloc(max_size, GFP_KERNEL);		if (!buf)			return -ENOMEM;	} 	if (buf == NULL)		return -EINVAL; 	if ((*ppos > max_size) ||	    (*ppos + count > max_size) ||	    (*ppos + count < count) ||	    (count > uncopied_bytes))		return -EINVAL; 	if (copy_from_user(buf + (*ppos), user_buf, count)) {		kfree(buf);		buf = NULL;		return -EFAULT;	} 	uncopied_bytes -= count;	*ppos += count; 	if (!uncopied_bytes) {		status = acpi_install_method(buf);		kfree(buf);		buf = NULL;		if (ACPI_FAILURE(status))			return -EINVAL;		add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);	} 	return count;} static const struct file_operations cm_fops = {	.write = cm_write,	.llseek = default_llseek,}; static int __init acpi_custom_method_init(void){	if (acpi_debugfs_dir == NULL)		return -ENOENT; 	cm_dentry = debugfs_create_file("custom_method", S_IWUSR,					acpi_debugfs_dir, NULL, &cm_fops);	if (cm_dentry == NULL)		return -ENODEV; 	return 0;} static void __exit acpi_custom_method_exit(void){	if (cm_dentry)		debugfs_remove(cm_dentry); } module_init(acpi_custom_method_init);module_exit(acpi_custom_method_exit);