On 09/29/2015 01:56 AM, Daniel Vetter wrote: > With atomic drivers we need to make sure that (at least in general) > property reads hold the right locks. But the legacy dpms property is > special and can be read locklessly. Since userspace loves to just > randomly look at that all the time (like with "status") do that. > > To make it clear that we play tricks use the READ_ONCE compiler > barrier (and also for paranoia). > > Note that there's not really anything bad going on since even with the > new atomic paths we eventually end up not chasing any pointers (and > hence possibly freed memory and other fun stuff). The locking WARNING > has been added in > > commit 88a48e297b3a3bac6022c03babfb038f1a886cea > Author: Rob Clark <robdclark at gmail.com> > Date: Thu Dec 18 16:01:50 2014 -0500 > > drm: add atomic properties > > but since drivers are converting not everyone will have seen this from > the start. > > Jens reported this and submitted a patch to just grab the > mode_config.connection_mutex, but we can do a bit better. > > v2: Remove unused variables I failed to git add for real. > > Reported-by: Jens Axboe <axboe at fb.com> > Cc: Jens Axboe <axboe at fb.com> > Cc: Rob Clark <robdclark at gmail.com> > Cc: stable at vger.kernel.org > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Works for me, thanks Daniel. Tested-by: Jens Axboe <axboe at fb.com> -- Jens Axboe
