Re: [PATCH 1/4] introduce intel_ring_buffer structure

[Simon Farnsworth <simon.farnsworth@onelan.com>]

On Wednesday 19 May 2010, "Zou, Nanhai" <nanhai.zou@intel.com> wrote:
> 	Currently we do not find any regression or slowness. We have been testing
> full HD video test along with regression tests for more than 1 month. The
> only slowness we find now is with playing 2 1080p H.264 video. That was
> caused by too much GPU memory usage which is not related to the interface.
> 
And are you utterly confident that if anyone finds a way to use your new ioctl 
to (e.g.) hang the GPU, stall rendering indefinitely waiting for media engine 
events that will never happen, or perhaps bypass system security, you can fix 
it without changing the ioctl interface to userspace? If not, you have a 
problem, and need to redesign the ioctl.

Bear in mind that I don't have to use VAAPI to call your ioctl; I can write 
evil code that calls it directly. On the other hand, you can't remove the 
ioctl later - users will want to use older VAAPI versions with new kernels, so 
that they can upgrade without too much fear of regression.
-- 
Simon Farnsworth
Software Engineer
ONELAN Limited
http://www.onelan.com/