[u]

[..]
  1. u_char
  2. uid_t
  3. umode_t
  4. un_wp_page
  5. unexpected_hd_interrupt
  6. unlock_buffer
  7. unlock_inode
  8. usage
  9. ushort
  10. ustat
  11. utimbuf
  12. utsname
[..]