drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()

Implement pinning without locking in nouveau_bo_pin_locked(). Keep
nouveau_bo_pin() for acquiring the buffer object's reservation lock.
The new helper will be useful for implementing the GEM pin callback
with correct semantics. Same for unpin.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # virtio-gpu
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240227113853.8464-6-tzimmermann@suse.de

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -467,17 +467,14 @@ nouveau_bo_placement_set(struct nouveau_bo *nvbo, uint32_t domain,
 	set_placement_range(nvbo, domain);
 }
 
-int
-nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
+int nouveau_bo_pin_locked(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_buffer_object *bo = &nvbo->bo;
 	bool force = false, evict = false;
-	int ret;
+	int ret = 0;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return ret;
+	dma_resv_assert_held(bo->base.resv);
 
 	if (drm->client.device.info.family >= NV_DEVICE_INFO_V0_TESLA &&
 	    domain == NOUVEAU_GEM_DOMAIN_VRAM && contig) {
@@ -540,20 +537,15 @@ nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
 out:
 	if (force && ret)
 		nvbo->contig = false;
-	ttm_bo_unreserve(bo);
 	return ret;
 }
 
-int
-nouveau_bo_unpin(struct nouveau_bo *nvbo)
+void nouveau_bo_unpin_locked(struct nouveau_bo *nvbo)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_buffer_object *bo = &nvbo->bo;
-	int ret;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return ret;
+	dma_resv_assert_held(bo->base.resv);
 
 	ttm_bo_unpin(&nvbo->bo);
 	if (!nvbo->bo.pin_count) {
@@ -568,8 +560,33 @@ nouveau_bo_unpin(struct nouveau_bo *nvbo)
 			break;
 		}
 	}
+}
+
+int nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
+{
+	struct ttm_buffer_object *bo = &nvbo->bo;
+	int ret;
 
+	ret = ttm_bo_reserve(bo, false, false, NULL);
+	if (ret)
+		return ret;
+	ret = nouveau_bo_pin_locked(nvbo, domain, contig);
+	ttm_bo_unreserve(bo);
+
+	return ret;
+}
+
+int nouveau_bo_unpin(struct nouveau_bo *nvbo)
+{
+	struct ttm_buffer_object *bo = &nvbo->bo;
+	int ret;
+
+	ret = ttm_bo_reserve(bo, false, false, NULL);
+	if (ret)
+		return ret;
+	nouveau_bo_unpin_locked(nvbo);
 	ttm_bo_unreserve(bo);
+
 	return 0;
 }
 

drivers/gpu/drm/nouveau/nouveau_bo.h

@@ -85,6 +85,8 @@ int  nouveau_bo_new(struct nouveau_cli *, u64 size, int align, u32 domain,
 		    u32 tile_mode, u32 tile_flags, struct sg_table *sg,
 		    struct dma_resv *robj,
 		    struct nouveau_bo **);
+int  nouveau_bo_pin_locked(struct nouveau_bo *nvbo, uint32_t domain, bool contig);
+void nouveau_bo_unpin_locked(struct nouveau_bo *nvbo);
 int  nouveau_bo_pin(struct nouveau_bo *, u32 flags, bool contig);
 int  nouveau_bo_unpin(struct nouveau_bo *);
 int  nouveau_bo_map(struct nouveau_bo *);