The following patch series fixes the mutex corruption problem due to bit-copying of drm_crtc structure that happens when drm_crtc_helper_set_config function takes the error-recovery path. The patch series is the alternative solution for the patch that was proposed and NACK-ed two weeks ago [1].
The actual fix is implemented in patch #6; preceding 5 patches are necessary prerequisites.
A couple of my own remarks:
1) Someone (including myself) may be tempted to eliminate the bit-copy for encoder and connector structures as well. I would, however, prefer to leave that improvement for a different patch series. The primary reason is that this patch series addresses an acute (and serious) problem (mutex corruption), while doing the equivalent rework for connector and encoder structure would be only for the sake of improving the code quality.
2) The problem exists in old (stable@...) kernels and my original intention (in the patch that was NACK-ed [1]) was to make the fix simple enough to be eligible for stable@.... This patch series is now probably more complex than what stable@... may be willing to accept. So the question in my mind is what we should do with the old kernels.
3) This patch series does not include the fix for incidental finding described in earlier discussions about this problem [2] because it's not the part of the fix that this patch series is targeting, so I'd leave it for later.
regards,
Ilija
[1] http://lists.freedesktop.org/archives/dri-devel/2013-October/047479.html [2] http://lists.freedesktop.org/archives/dri-devel/2013-October/047557.html