[RFC PATCH v1 04/16] drm/nouveau: require reservations for nouveau_fence_sync and nouveau_bo_fence

[Maarten Lankhorst]

This will ensure we always hold the required lock when calling those functions.
---
 drivers/gpu/drm/nouveau/nouveau_bo.c      |    2 ++
 drivers/gpu/drm/nouveau/nouveau_display.c |   17 +++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c 
b/drivers/gpu/drm/nouveau/nouveau_bo.c
index b6dc85c614be..33eb7164525a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -1431,6 +1431,8 @@ nouveau_bo_fence(struct nouveau_bo *nvbo, struct 
nouveau_fence *fence)
        struct nouveau_fence *new_fence = nouveau_fence_ref(fence);
        struct nouveau_fence *old_fence = NULL;

+       lockdep_assert_held(&nvbo->bo.resv->lock.base);
+
        spin_lock(&nvbo->bo.bdev->fence_lock);
        old_fence = nvbo->bo.sync_obj;
        nvbo->bo.sync_obj = new_fence;
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c 
b/drivers/gpu/drm/nouveau/nouveau_display.c
index da764a4ed958..61b8c3375135 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -716,6 +716,9 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc, struct 
drm_framebuffer *fb,
        }

        mutex_lock(&chan->cli->mutex);
+       ret = ttm_bo_reserve(&new_bo->bo, true, false, false, NULL);
+       if (ret)
+               goto fail_unpin;

        /* synchronise rendering channel with the kernel's channel */
        spin_lock(&new_bo->bo.bdev->fence_lock);
@@ -723,12 +726,18 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc, struct 
drm_framebuffer *fb,
        spin_unlock(&new_bo->bo.bdev->fence_lock);
        ret = nouveau_fence_sync(fence, chan);
        nouveau_fence_unref(&fence);
-       if (ret)
+       if (ret) {
+               ttm_bo_unreserve(&new_bo->bo);
                goto fail_unpin;
+       }

-       ret = ttm_bo_reserve(&old_bo->bo, true, false, false, NULL);
-       if (ret)
-               goto fail_unpin;
+       if (new_bo != old_bo) {
+               ttm_bo_unreserve(&new_bo->bo);
+
+               ret = ttm_bo_reserve(&old_bo->bo, true, false, false, NULL);
+               if (ret)
+                       goto fail_unpin;
+       }

        /* Initialize a page flip struct */
        *s = (struct nouveau_page_flip_state)