Daniel Vetter <daniel.vetter@xxxxxxxx> writes: > This came up in discussions when reviewing drm patches. > > Cc: Eric Anholt <eric@xxxxxxxxxx> > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: Jonathan Corbet <corbet@xxxxxxx> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > > -- > > Aside: I wonder whether we shouldn't move this to some other place and > rst-ify it? Any good suggestions? > -Daniel > --- > Documentation/ioctl/botching-up-ioctls.txt | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/Documentation/ioctl/botching-up-ioctls.txt b/Documentation/ioctl/botching-up-ioctls.txt > index d02cfb48901c..883fb034bd04 100644 > --- a/Documentation/ioctl/botching-up-ioctls.txt > +++ b/Documentation/ioctl/botching-up-ioctls.txt > @@ -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. I hadn't realized that we had this document in git, or I probably would have written this patch. I think this makes it clear enough how I got vc4 and v3d wrong. Thanks! Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
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