gpu: nvgpu: check sync existence in channel update

The channel sync object can get deleted before all channel updates have
finished if the channel is freed before them, so work around a null
dereference by testing if the sync exists. Channel and/or c->sync
refcounting would be necessary for proper fix.

Bug 200076344

Change-Id: Ica8ef2df9cd95cfa593cd4f41768dbb6641357b2
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/734266
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index 444a1c2f..5691a7cd 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -1331,7 +1331,8 @@ void gk20a_channel_update(struct channel_gk20a *c, int nr_completed)
                 if (!completed)
                         break;
 
-                c->sync->signal_timeline(c->sync);
+                if (c->sync)
+                        c->sync->signal_timeline(c->sync);
 
                 gk20a_vm_put_buffers(vm, job->mapped_buffers,
                                 job->num_mapped_buffers);