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| author | Eric Anholt <eric@anholt.net> | 2018-05-01 02:59:27 +0300 |
|---|---|---|
| committer | Eric Anholt <eric@anholt.net> | 2018-05-04 01:20:09 +0300 |
| commit | 4c70ac7639f6af6d7c2d01f0307665a4b9afada7 (patch) | |
| tree | 01ddc441926bc795463f9104eec134e2a233f643 /include | |
| parent | 0a4587a034a43e5076770df10446214cfb3de8f8 (diff) | |
| download | linux-4c70ac7639f6af6d7c2d01f0307665a4b9afada7.tar.xz | |
drm/vc4: Add a pad field to align drm_vc4_submit_cl to 64 bits.
I had originally asked Stefan Schake to drop the pad field from the
syncobj changes that just landed, because I couldn't come up with a
reason to align to 64 bits.
Talking with Dave Airlie about the new v3d driver's submit ioctl, we
came up with a reason: sizeof() on 64-bit platforms may align to 64
bits, in which case the userspace will be submitting the aligned size
and the final 32 bits won't be zero-padded by the kernel. If
userspace doesn't zero-fill, then a future ABI change adding a 32-bit
field at the end could potentially cause the kernel to read undefined
data from old userspace (our userspace happens to use structure
initialization that zero-fills, but as a general rule we try not to
rely on that in the kernel).
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180430235927.28712-1-eric@anholt.net
Reviewed-by: Stefan Schake <stschake@gmail.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/drm/vc4_drm.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/uapi/drm/vc4_drm.h b/include/uapi/drm/vc4_drm.h index 2be4fe3610b8..2cac6277a1d7 100644 --- a/include/uapi/drm/vc4_drm.h +++ b/include/uapi/drm/vc4_drm.h @@ -193,6 +193,8 @@ struct drm_vc4_submit_cl { * render job. 0 means ignore. */ __u32 out_sync; + + __u32 pad2; }; /** |