On Thu, Jul 29, 2021 at 9:52 PM John Stultz <john.stultz@xxxxxxxxxx> wrote: > > On Thu, Jul 29, 2021 at 12:24 AM Daniel Vetter <daniel@xxxxxxxx> 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@xxxxxxx> > > > > 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/libsync/sync.c;l=416 Hello, Like John mentioned, CONFIG_SW_SYNC is not turned on for the *-5.4 and newer branches in the Android Common Kernel. The references in AOSP are only in place to support devices with older kernels upgrading to newer Android versions. Regards, Hridya > > 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
