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Commit 1897e8f3 authored by Daniel Vetter's avatar Daniel Vetter Committed by Jonathan Corbet
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doc: botching-up-ioctls: Make it clearer why structs must be padded 



This came up in discussions when reviewing drm patches.

Reviewed-by: default avatarEric Anholt <eric@anholt.net>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent c9161088

Documentation/ioctl/botching-up-ioctls.txt

+3 −1
Original line number Diff line number Diff line
@@ -73,7 +73,9 @@ will have a second iteration or at least an extension for any given interface. 
   future extensions is going right down the gutters since someone will submit

   an ioctl struct with random stack garbage in the yet unused parts. Which

   then bakes in the ABI that those fields can never be used for anything else

   but garbage.

   but garbage. This is also the reason why you must explicitly pad all

   structures, even if you never use them in an array - the padding the compiler

   might insert could contain garbage.



 * Have simple testcases for all of the above.