drm/panfrost: Make sure a BO is only unmapped when appropriate

mmu_ops->unmap() will fail when called on a BO that has not been
previously mapped, and the error path in panfrost_ioctl_create_bo()
can call drm_gem_object_put_unlocked() (which in turn calls
panfrost_mmu_unmap()) on a BO that has not been mapped yet.

Keep track of the mapped/unmapped state to avoid such issues.

Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
Cc: <[e-mail]>
Signed-off-by: Boris Brezillon <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panfrost/panfrost_gem.c

···
 	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
 	struct panfrost_device *pfdev = obj->dev->dev_private;
 
-	panfrost_mmu_unmap(bo);
+	if (bo->is_mapped)
+		panfrost_mmu_unmap(bo);
 
 	spin_lock(&pfdev->mm_lock);
 	drm_mm_remove_node(&bo->node);

drivers/gpu/drm/panfrost/panfrost_gem.h

···
 	struct drm_gem_shmem_object base;
 
 	struct drm_mm_node node;
+	bool is_mapped;
 };
 
 static inline

drivers/gpu/drm/panfrost/panfrost_mmu.c

···
 	struct sg_table *sgt;
 	int ret;
 
+	if (WARN_ON(bo->is_mapped))
+		return 0;
+
 	sgt = drm_gem_shmem_get_pages_sgt(obj);
 	if (WARN_ON(IS_ERR(sgt)))
 		return PTR_ERR(sgt);
···
 
 	pm_runtime_mark_last_busy(pfdev->dev);
 	pm_runtime_put_autosuspend(pfdev->dev);
+	bo->is_mapped = true;
 
 	return 0;
 }
···
 	size_t len = bo->node.size << PAGE_SHIFT;
 	size_t unmapped_len = 0;
 	int ret;
+
+	if (WARN_ON(!bo->is_mapped))
+		return;
 
 	dev_dbg(pfdev->dev, "unmap: iova=%llx, len=%zx", iova, len);
 
···
 
 	pm_runtime_mark_last_busy(pfdev->dev);
 	pm_runtime_put_autosuspend(pfdev->dev);
+	bo->is_mapped = false;
 }
 
 static void mmu_tlb_inv_context_s1(void *cookie)