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Commit 0ae6d7bc authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/nouveau: try to protect nbo->pin_refcount 



... by moving the bo_pin/bo_unpin manipulation of the pin_refcount
under the protection of the ttm reservation lock. pin/unpin seems
to get called from all over the place, so atm this is completely racy.

After this patch there are only a few places in cleanup functions
left which access ->pin_refcount without locking. But I'm hoping that
those are safe and some other code invariant guarantees that this
won't blow up.

In any case, I only need to fix up pin/unpin to make ->pageflip work
safely, so let's keep it at that.

Add a comment to the header to explain the new locking rule.

Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 59ad1465

drivers/gpu/drm/nouveau/nouveau_bo.c

+11 −11
Original line number Diff line number Diff line
@@ -300,17 +300,18 @@ nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t memtype) 
	struct ttm_buffer_object *bo = &nvbo->bo;

	int ret;



	ret = ttm_bo_reserve(bo, false, false, false, 0);

	if (ret)

		goto out;



	if (nvbo->pin_refcnt && !(memtype & (1 << bo->mem.mem_type))) {

		NV_ERROR(drm, "bo %p pinned elsewhere: 0x%08x vs 0x%08x\n", bo,

			 1 << bo->mem.mem_type, memtype);

		return -EINVAL;

		ret = -EINVAL;

		goto out;

	}



	if (nvbo->pin_refcnt++)

		return 0;



	ret = ttm_bo_reserve(bo, false, false, false, 0);

	if (ret)

		goto out;



	nouveau_bo_placement_set(nvbo, memtype, 0);
@@ -328,10 +329,8 @@ nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t memtype) 
			break;

		}

	}

	ttm_bo_unreserve(bo);

out:

	if (unlikely(ret))

		nvbo->pin_refcnt--;

	ttm_bo_unreserve(bo);

	return ret;

}
@@ -342,13 +341,13 @@ nouveau_bo_unpin(struct nouveau_bo *nvbo) 
	struct ttm_buffer_object *bo = &nvbo->bo;

	int ret;



	if (--nvbo->pin_refcnt)

		return 0;



	ret = ttm_bo_reserve(bo, false, false, false, 0);

	if (ret)

		return ret;



	if (--nvbo->pin_refcnt)

		goto out;



	nouveau_bo_placement_set(nvbo, bo->mem.placement, 0);



	ret = nouveau_bo_validate(nvbo, false, false);
@@ -365,6 +364,7 @@ nouveau_bo_unpin(struct nouveau_bo *nvbo) 
		}

	}



out:

	ttm_bo_unreserve(bo);

	return ret;

}

drivers/gpu/drm/nouveau/nouveau_bo.h

+2 −0
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ struct nouveau_bo { 
	struct nouveau_drm_tile *tile;



	struct drm_gem_object *gem;



	/* protect by the ttm reservation lock */

	int pin_refcnt;



	struct ttm_bo_kmap_obj dma_buf_vmap;