On Fri, 26 Jul 2024 14:37:53 +1000
Ben Skeggs <bske...@nvidia.com> wrote:

> Unify some more of the PCI/Tegra DRM driver init, both as a general
> cleanup, and because a subsequent commit changes the pointer stored
> via dev_set_drvdata(), and this allows the change to be made in one
> place.
> 
> Signed-off-by: Ben Skeggs <bske...@nvidia.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_drm.c      | 93
> ++++++++++++++-------- drivers/gpu/drm/nouveau/nouveau_platform.c |
> 6 -- 2 files changed, 60 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
> b/drivers/gpu/drm/nouveau/nouveau_drm.c index
> eae48c87e3d5..9beff8737617 100644 ---
> a/drivers/gpu/drm/nouveau/nouveau_drm.c +++
> b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -628,20 +628,14 @@
> nouveau_drm_device_fini(struct drm_device *dev)
> destroy_workqueue(drm->sched_wq); nvif_parent_dtor(&drm->parent);
>       mutex_destroy(&drm->clients_lock);
> -     kfree(drm);
>  }
>  
>  static int
> -nouveau_drm_device_init(struct drm_device *dev)
> +nouveau_drm_device_init(struct nouveau_drm *drm)
>  {
> -     struct nouveau_drm *drm;
> +     struct drm_device *dev = drm->dev;
>       int ret;
>  
> -     if (!(drm = kzalloc(sizeof(*drm), GFP_KERNEL)))
> -             return -ENOMEM;
> -     dev->dev_private = drm;
> -     drm->dev = dev;
> -
>       nvif_parent_ctor(&nouveau_parent, &drm->parent);
>       drm->master.base.object.parent = &drm->parent;
>  
> @@ -711,6 +705,12 @@ nouveau_drm_device_init(struct drm_device *dev)
>               pm_runtime_put(dev->dev);
>       }
>  
> +     ret = drm_dev_register(drm->dev, 0);
> +     if (ret) {
> +             nouveau_drm_device_fini(drm->dev);
> +             return ret;
> +     }
> +
>       return 0;
>  fail_dispinit:
>       nouveau_display_destroy(dev);
> @@ -728,10 +728,47 @@ nouveau_drm_device_init(struct drm_device *dev)
>       destroy_workqueue(drm->sched_wq);
>  fail_alloc:
>       nvif_parent_dtor(&drm->parent);
> -     kfree(drm);
>       return ret;
>  }
>  
> +static void
> +nouveau_drm_device_del(struct nouveau_drm *drm)
> +{
> +     if (drm->dev)
> +             drm_dev_put(drm->dev);
> +

Out of curiosity, Is it a valid convention in nouveau that allowing to
call the de-constructor of the *failing* object construction in the
error handling path? This usually means the de-constructor has to clean
the half-baked object silently while not be able to catch an invalid use
of the object somewhere else. 

E.g. if (drm->dev)... seems more like for error handling. In a normal
tearing down path, if !drm->dev, then a WARN_ON() or OOPs is expected
to catch the case. IMO, we should not let it slip away silently.

> +     kfree(drm);
> +}
> +
> +static struct nouveau_drm *
> +nouveau_drm_device_new(const struct drm_driver *drm_driver, struct
> device *parent,
> +                    struct nvkm_device *device)
> +{
> +     struct nouveau_drm *drm;
> +     int ret;
> +
> +     drm = kzalloc(sizeof(*drm), GFP_KERNEL);
> +     if (!drm)
> +             return ERR_PTR(-ENOMEM);
> +
> +     drm->dev = drm_dev_alloc(drm_driver, parent);
> +     if (IS_ERR(drm->dev)) {
> +             ret = PTR_ERR(drm->dev);
> +             goto done;
> +     }
> +
> +     drm->dev->dev_private = drm;
> +     dev_set_drvdata(parent, drm->dev);
> +
> +done:
> +     if (ret) {
> +             nouveau_drm_device_del(drm);
> +             drm = NULL;
> +     }
> +
> +     return ret ? ERR_PTR(ret) : drm;
> +}
> +
>  /*
>   * On some Intel PCIe bridge controllers doing a
>   * D0 -> D3hot -> D3cold -> D0 sequence causes Nvidia GPUs to not
> reappear. @@ -794,7 +831,7 @@ static int nouveau_drm_probe(struct
> pci_dev *pdev, const struct pci_device_id *pent)
>  {
>       struct nvkm_device *device;
> -     struct drm_device *drm_dev;
> +     struct nouveau_drm *drm;
>       int ret;
>  
>       if (vga_switcheroo_client_probe_defer(pdev))
> @@ -825,9 +862,9 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
>       if (nouveau_atomic)
>               driver_pci.driver_features |= DRIVER_ATOMIC;
>  
> -     drm_dev = drm_dev_alloc(&driver_pci, &pdev->dev);
> -     if (IS_ERR(drm_dev)) {
> -             ret = PTR_ERR(drm_dev);
> +     drm = nouveau_drm_device_new(&driver_pci, &pdev->dev,
> device);
> +     if (IS_ERR(drm)) {
> +             ret = PTR_ERR(drm);
>               goto fail_nvkm;
>       }
>  
> @@ -835,30 +872,22 @@ static int nouveau_drm_probe(struct pci_dev
> *pdev, if (ret)
>               goto fail_drm;
>  
> -     pci_set_drvdata(pdev, drm_dev);
> -
> -     ret = nouveau_drm_device_init(drm_dev);
> +     ret = nouveau_drm_device_init(drm);
>       if (ret)
>               goto fail_pci;
>  
> -     ret = drm_dev_register(drm_dev, pent->driver_data);
> -     if (ret)
> -             goto fail_drm_dev_init;
> -
> -     if (nouveau_drm(drm_dev)->client.device.info.ram_size <= 32
> * 1024 * 1024)
> -             drm_fbdev_ttm_setup(drm_dev, 8);
> +     if (drm->client.device.info.ram_size <= 32 * 1024 * 1024)
> +             drm_fbdev_ttm_setup(drm->dev, 8);
>       else
> -             drm_fbdev_ttm_setup(drm_dev, 32);
> +             drm_fbdev_ttm_setup(drm->dev, 32);
>  
>       quirk_broken_nv_runpm(pdev);
>       return 0;
>  
> -fail_drm_dev_init:
> -     nouveau_drm_device_fini(drm_dev);
>  fail_pci:
>       pci_disable_device(pdev);
>  fail_drm:
> -     drm_dev_put(drm_dev);
> +     nouveau_drm_device_del(drm);
>  fail_nvkm:
>       nvkm_device_del(&device);
>       return ret;
> @@ -877,7 +906,7 @@ nouveau_drm_device_remove(struct drm_device *dev)
>       device = nvkm_device_find(client->device);
>  
>       nouveau_drm_device_fini(dev);
> -     drm_dev_put(dev);
> +     nouveau_drm_device_del(drm);
>       nvkm_device_del(&device);
>  }
>  
> @@ -1369,7 +1398,7 @@ nouveau_platform_device_create(const struct
> nvkm_device_tegra_func *func, struct platform_device *pdev,
>                              struct nvkm_device **pdevice)
>  {
> -     struct drm_device *drm;
> +     struct nouveau_drm *drm;
>       int err;
>  
>       err = nvkm_device_tegra_new(func, pdev, nouveau_config,
> nouveau_debug, @@ -1377,7 +1406,7 @@
> nouveau_platform_device_create(const struct nvkm_device_tegra_func
> *func, if (err) goto err_free;
>  
> -     drm = drm_dev_alloc(&driver_platform, &pdev->dev);
> +     drm = nouveau_drm_device_new(&driver_platform, &pdev->dev,
> *pdevice); if (IS_ERR(drm)) {
>               err = PTR_ERR(drm);
>               goto err_free;
> @@ -1387,12 +1416,10 @@ nouveau_platform_device_create(const struct
> nvkm_device_tegra_func *func, if (err)
>               goto err_put;
>  
> -     platform_set_drvdata(pdev, drm);
> -
> -     return drm;
> +     return drm->dev;
>  
>  err_put:
> -     drm_dev_put(drm);
> +     nouveau_drm_device_del(drm);
>  err_free:
>       nvkm_device_del(pdevice);
>  
> diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c
> b/drivers/gpu/drm/nouveau/nouveau_platform.c index
> bf2dc7567ea4..d0a63f0f54a2 100644 ---
> a/drivers/gpu/drm/nouveau/nouveau_platform.c +++
> b/drivers/gpu/drm/nouveau/nouveau_platform.c @@ -34,12 +34,6 @@
> static int nouveau_platform_probe(struct platform_device *pdev) if
> (IS_ERR(drm)) return PTR_ERR(drm);
>  
> -     ret = drm_dev_register(drm, 0);
> -     if (ret < 0) {
> -             drm_dev_put(drm);
> -             return ret;
> -     }
> -
>       return 0;
>  }
>  

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