-int lprocfs_call_handler(void *data, int write, loff_t *ppos, void *buffer,
- size_t *lenp, int (*handler)(void *data, int write,
- loff_t pos, void *buffer, int len));
+int lprocfs_call_handler(void *data, int write, loff_t *ppos,
+ void __user *buffer, size_t *lenp,
+ int (*handler)(void *data, int write,
+ loff_t pos, void __user *buffer, int len));