drm/nouveau: Make fences take a weak channel reference.

Fences didn't increment the channel reference count, and the fenced
channel could go away at any time. Fixes a potential race in
nouveau_fence_update().

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 0a22955998e8..e1ae9bab6e41 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -64,6 +64,7 @@ nouveau_fence_del(struct kref *ref)
         struct nouveau_fence *fence =
                 container_of(ref, struct nouveau_fence, refcount);
 
+        nouveau_channel_ref(NULL, &fence->channel);
         kfree(fence);
 }
 
@@ -113,7 +114,7 @@ nouveau_fence_new(struct nouveau_channel *chan, struct nouveau_fence **pfence,
         if (!fence)
                 return -ENOMEM;
         kref_init(&fence->refcount);
-        fence->channel = chan;
+        nouveau_channel_ref(chan, &fence->channel);
 
         if (emit)
                 ret = nouveau_fence_emit(fence);