On Thu, Jul 29, 2021 at 12:24 AM Daniel Vetter daniel@ffwll.ch wrote:
On Thu, Jul 29, 2021 at 09:03:30AM +0200, Christian König wrote:
As we now knew controlling dma_fence synchronization from userspace is extremely dangerous and can not only deadlock drivers but trivially also the whole kernel memory management.
Entirely remove this option. We now have in kernel unit tests to exercise the dma_fence framework and it's containers.
Signed-off-by: Christian König christian.koenig@amd.com
There's also igts for this, and Android heavily uses this. So I'm not sure we can just nuke it.
Eeeeh... I don't think that's actually the case anymore. As of android12-5.10 CONFIG_SW_SYNC is not turned on. Further, Android is disabling debugfs in their kernels as it exposes too much to userland.
That said, there still are some references to it: https://cs.android.com/android/platform/superproject/+/master:system/core/li...
But it looks like the actual users are only kselftest and igt?
Adding Alistair, Hridya and Sandeep in case they have more context.
thanks -john