tree 598ddd92e822e0734348d4d74dca2073182f82d3
parent 951499710be258b85c135ee1f7ebe5f7a4b7ac91
author Laura Abbott <labbott@redhat.com> 1472856144 -0700
committer Jonathan Corbet <corbet@lwn.net> 1473163222 -0600

doc: ioctl: Add some clarifications to botching-up-ioctls

- The guide currently says to pad the structure to a multiple of
  64-bits. This is not necessary in cases where the structure contains
  no 64-bit types. Clarify this concept to avoid unnecessary padding.
- When using __u64 to hold user pointers, blindly trying to do a cast to
  a void __user * may generate a warning on 32-bit systems about a cast
  from an integer to a pointer of different size. There is a macro to
  deal with this which hides an ugly double cast. Add a reference to
  this macro.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>