-int cfs_trace_copyin_string(char *knl_buffer, int knl_buffer_nob,
- const char __user *usr_buffer, int usr_buffer_nob);
int cfs_trace_copyout_string(char __user *usr_buffer, int usr_buffer_nob,
const char *knl_str, char *append);
int cfs_trace_allocate_string_buffer(char **str, int nob);