On Thu, Jun 26, 2025 at 8:32 PM Maíra Canal <[email protected]> wrote: > > Hi Pranav, > > On 26/06/25 11:22, Pranav Tyagi wrote: > > From: Maíra Canal <[email protected]> > > > > [ Upstream commit a0e6a017ab56936c0405fe914a793b241ed25ee0 ] > > > > Currently, it is possible for the composer to be set as enabled and then > > as disabled without a proper call for the vkms_vblank_simulate(). This > > is problematic, because the driver would skip one CRC output, causing CRC > > tests to fail. Therefore, we need to make sure that, for each time the > > composer is set as enabled, a composer job is added to the queue. > > > > In order to provide this guarantee, add a mutex that will lock before > > the composer is set as enabled and will unlock only after the composer > > job is added to the queue. This way, we can have a guarantee that the > > driver won't skip a CRC entry. > > > > This race-condition is affecting the IGT test "writeback-check-output", > > making the test fail and also, leaking writeback framebuffers, as the > > writeback job is queued, but it is not signaled. This patch avoids both > > problems. > > > > [v2]: > > * Create a new mutex and keep the spinlock across the atomic commit in > > order to avoid interrupts that could result in deadlocks. > > > > [ Backport to 5.15: context cleanly applied with no semantic changes. > > Build-tested. ] > > > > Signed-off-by: Maíra Canal <[email protected]> > > Reviewed-by: Arthur Grillo <[email protected]> > > Signed-off-by: Maíra Canal <[email protected]> > > Link: > > https://patchwork.freedesktop.org/patch/msgid/[email protected] > > Signed-off-by: Pranav Tyagi <[email protected]> > > This patch violates locking rules and it was reversed a while ago. > Please, check commit 7908632f2927 ("Revert "drm/vkms: Fix race-condition > between the hrtimer and the atomic commit""). > > Best Regards, > - Maíra
Thanks for pointing that out. I missed the revert. I now see that commit 7908632f2927 reversed this due to locking issues. I’ll drop this backport from 5.15 accordingly. Regards Pranav Tyagi
