Hello,

I propose to add the following commonly used RTDM inline functions to
rtdm_driver.h:

    static inline int rtdm_safe_copy_from_user()
    static inline int rtdm_safe_copy_to_user()

The attached patch also fixes a bug in rtdm_strncpy_from_user(). I think
__xn_access_ok() returns a non-zero value if the access is safe. Has it
ever worked? I don't care about the real name.

Wolfgang.