Re: [Nouveau] [PATCH 2/3] drm/nouveau: manage nouveau_drm lifetime with devres
From: Karol Herbst
Date: Fri Nov 06 2020 - 08:32:03 EST
On Fri, Nov 6, 2020 at 3:17 AM Jeremy Cline <jcline@xxxxxxxxxx> wrote:
>
> Make use of the devm_drm_dev_alloc() API to bind the lifetime of
> nouveau_drm structure to the drm_device. This is important because a
> reference to nouveau_drm is accessible from drm_device, which is
> provided to a number of DRM layer callbacks that can run after the
> deallocation of nouveau_drm currently occurs.
>
> Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
> ---
> drivers/gpu/drm/nouveau/nouveau_drm.c | 44 ++++++++++++---------------
> drivers/gpu/drm/nouveau/nouveau_drv.h | 10 ++++--
> 2 files changed, 26 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index bc6f51bf23b7..f750c25e92f9 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -30,9 +30,11 @@
> #include <linux/vga_switcheroo.h>
> #include <linux/mmu_notifier.h>
>
> +#include <drm/drm_drv.h>
> #include <drm/drm_crtc_helper.h>
> #include <drm/drm_ioctl.h>
> #include <drm/drm_vblank.h>
> +#include <drm/drm_managed.h>
>
> #include <core/gpuobj.h>
> #include <core/option.h>
> @@ -532,13 +534,8 @@ nouveau_parent = {
> static int
> nouveau_drm_device_init(struct drm_device *dev)
> {
> - struct nouveau_drm *drm;
> int ret;
> -
> - if (!(drm = kzalloc(sizeof(*drm), GFP_KERNEL)))
> - return -ENOMEM;
> - dev->dev_private = drm;
> - drm->dev = dev;
> + struct nouveau_drm *drm = nouveau_drm(dev);
>
> nvif_parent_ctor(&nouveau_parent, &drm->parent);
> drm->master.base.object.parent = &drm->parent;
> @@ -620,7 +617,6 @@ nouveau_drm_device_init(struct drm_device *dev)
> nouveau_cli_fini(&drm->master);
> fail_alloc:
> nvif_parent_dtor(&drm->parent);
> - kfree(drm);
> return ret;
> }
>
> @@ -654,7 +650,6 @@ nouveau_drm_device_fini(struct drm_device *dev)
> nouveau_cli_fini(&drm->client);
> nouveau_cli_fini(&drm->master);
> nvif_parent_dtor(&drm->parent);
> - kfree(drm);
> }
>
> /*
> @@ -720,6 +715,7 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
> {
> struct nvkm_device *device;
> struct drm_device *drm_dev;
> + struct nouveau_drm *nv_dev;
> int ret;
>
> if (vga_switcheroo_client_probe_defer(pdev))
> @@ -750,15 +746,16 @@ 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);
> + nv_dev = devm_drm_dev_alloc(&pdev->dev, &driver_stub, typeof(*nv_dev), drm_dev);
> + if (IS_ERR(nv_dev)) {
> + ret = PTR_ERR(nv_dev);
> goto fail_nvkm;
> }
> + drm_dev = nouveau_to_drm_dev(nv_dev);
>
> ret = pci_enable_device(pdev);
> if (ret)
> - goto fail_drm;
> + goto fail_nvkm;
>
> drm_dev->pdev = pdev;
> pci_set_drvdata(pdev, drm_dev);
> @@ -778,8 +775,6 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
> nouveau_drm_device_fini(drm_dev);
> fail_pci:
> pci_disable_device(pdev);
> -fail_drm:
> - drm_dev_put(drm_dev);
it sounded like that when using devm_drm_dev_alloc we still have an
initial refcount of 1, so at least in this regard nothing changed so I
am wondering why this change is necessary and if the reason is
unrelated it might make sense to move it into its own patch.
> fail_nvkm:
> nvkm_device_del(&device);
> return ret;
> @@ -799,7 +794,6 @@ nouveau_drm_device_remove(struct drm_device *dev)
> device = nvkm_device_find(client->device);
>
> nouveau_drm_device_fini(dev);
> - drm_dev_put(dev);
> nvkm_device_del(&device);
> }
>
> @@ -1285,7 +1279,8 @@ 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 *nv_dev;
> + struct drm_device *drm_dev;
> int err;
>
> err = nvkm_device_tegra_new(func, pdev, nouveau_config, nouveau_debug,
> @@ -1293,22 +1288,21 @@ nouveau_platform_device_create(const struct nvkm_device_tegra_func *func,
> if (err)
> goto err_free;
>
> - drm = drm_dev_alloc(&driver_platform, &pdev->dev);
> - if (IS_ERR(drm)) {
> - err = PTR_ERR(drm);
> + nv_dev = devm_drm_dev_alloc(&pdev->dev, &driver_platform, typeof(*nv_dev), drm_dev);
> + if (IS_ERR(nv_dev)) {
> + err = PTR_ERR(nv_dev);
> goto err_free;
> }
> + drm_dev = nouveau_to_drm_dev(nv_dev);
>
> - err = nouveau_drm_device_init(drm);
> + err = nouveau_drm_device_init(drm_dev);
> if (err)
> - goto err_put;
> + goto err_free;
>
> - platform_set_drvdata(pdev, drm);
> + platform_set_drvdata(pdev, drm_dev);
>
> - return drm;
> + return drm_dev;
>
> -err_put:
> - drm_dev_put(drm);
> err_free:
> nvkm_device_del(pdevice);
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
> index 3e2920a10099..cf6c33e52a5c 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drv.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
> @@ -137,7 +137,11 @@ struct nouveau_drm {
> struct nvif_parent parent;
> struct nouveau_cli master;
> struct nouveau_cli client;
> - struct drm_device *dev;
> +
> + /**
> + * @drm_dev: The parent DRM device object.
> + */
> + struct drm_device drm_dev;
>
> struct list_head clients;
>
> @@ -237,7 +241,7 @@ struct nouveau_drm {
> static inline struct nouveau_drm *
> nouveau_drm(struct drm_device *dev)
> {
> - return dev->dev_private;
> + return container_of(dev, struct nouveau_drm, drm_dev);
> }
>
> /**
> @@ -251,7 +255,7 @@ nouveau_drm(struct drm_device *dev)
> */
> static inline struct drm_device *
> nouveau_to_drm_dev(struct nouveau_drm *nv_dev) {
> - return nv_dev->dev;
> + return &nv_dev->drm_dev;
> }
>
> /**
> --
> 2.28.0
>
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