Hi
On Tue, Jan 21, 2014 at 12:42 PM, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
On Tue, Jan 21, 2014 at 12:17:35PM +0100, David Herrmann wrote:
Hi
On Tue, Jan 21, 2014 at 10:49 AM, Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Jan 20, 2014 at 08:26:28PM +0100, David Herrmann wrote:
Lets make sure some basic expressions are always true: bpp != NULL width != NULL height != NULL stride = bpp * width < 2^32 size = stride * height < 2^32 PAGE_ALIGN(size) < 2^32
At least the udl driver doesn't check for multiplication-overflows, so lets just make sure it will never happen. These checks allow drivers to do any 32bit math without having to test for mult-overflows themselves.
The two divisions might hurt performance a bit, but dumb_create() is only used for scanout-buffers, so that should be fine. We could use 64bit math to avoid the divisions, but that may be slow on 32bit machines.. Or maybe there should just be a "safe_mult32()" helper, which currently doesn't exist (I think?).
Signed-off-by: David Herrmann dh.herrmann@gmail.com
drivers/gpu/drm/drm_crtc.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 266a01d..ff647fa 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -3738,9 +3738,24 @@ int drm_mode_create_dumb_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { struct drm_mode_create_dumb *args = data;
u32 Bpp, stride, size;s/Bpp/bpp/
It's actually "Bytes per pixel", not "Bits per pixel". We generally use "bpp" as "bits per pixel" so I'd like to avoid the confusion. But yeah, upper-case names are unusual so I can also use bytes_pp or sth similar?
cpp is fairly commonly used for bytes per pixel, if you want to stick to something short but still recognizable.
Because "c" comes after "b"? Or is there any other logic here? But sounds good, will send a v2 shortly.
Thanks David