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charset=UTF-8 Date: Thu, 02 Jul 2026 15:36:19 +0900 Message-Id: Cc: , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v5 13/19] rust: drm: Wrap ioctl dispatch in RegistrationGuard From: "Alexandre Courbot" To: "Danilo Krummrich" References: <20260628145406.2107056-1-dakr@kernel.org> <20260628145406.2107056-14-dakr@kernel.org> In-Reply-To: <20260628145406.2107056-14-dakr@kernel.org> X-ClientProxiedBy: OS7P301CA0027.JPNP301.PROD.OUTLOOK.COM (2603:1096:604:26b::18) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|SA1PR12MB8141:EE_ X-MS-Office365-Filtering-Correlation-Id: e4d3945f-2497-4c0a-c20e-08ded8043b77 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|23010399003|10070799003|3023799007|4143699003|18002099003|5023799004|56012099006|11063799006|22082099003; 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Maybe change to something like "Make ioctl handlers receive...". > > This is achieved by calling registration_guard() on the Device > obtained in ioctl dispatch context. If the device has been unplugged, > the ioctl returns -ENODEV without calling the handler. > > To resolve the driver type parameter T for type inference, which the > compiler cannot propagate through method resolution and associated-type > projections alone, a dead-code closure and a helper function are used as > a type-inference anchor. > > Reviewed-by: Lyude Paul > Signed-off-by: Danilo Krummrich > --- > drivers/gpu/drm/nova/file.rs | 12 ++++++---- > drivers/gpu/drm/tyr/file.rs | 7 ++++-- > rust/kernel/drm/ioctl.rs | 45 +++++++++++++++++++++++++++++++++--- > 3 files changed, 55 insertions(+), 9 deletions(-) > > diff --git a/drivers/gpu/drm/nova/file.rs b/drivers/gpu/drm/nova/file.rs > index a3b7bd36792c..19fb89b28984 100644 > --- a/drivers/gpu/drm/nova/file.rs > +++ b/drivers/gpu/drm/nova/file.rs > @@ -4,7 +4,11 @@ > use crate::gem::NovaObject; > use kernel::{ > alloc::flags::*, > - drm::{self, gem::BaseObject}, > + drm::{ > + self, > + gem::BaseObject, > + Registered, // > + }, > pci, > prelude::*, > uapi, > @@ -23,7 +27,7 @@ fn open(_dev: &NovaDevice) -> Result>> { > impl File { > /// IOCTL: get_param: Query GPU / driver metadata. > pub(crate) fn get_param( > - dev: &NovaDevice, > + dev: &NovaDevice, > getparam: &mut uapi::drm_nova_getparam, > _file: &drm::File, > ) -> Result { > @@ -43,7 +47,7 @@ pub(crate) fn get_param( > =20 > /// IOCTL: gem_create: Create a new DRM GEM object. > pub(crate) fn gem_create( > - dev: &NovaDevice, > + dev: &NovaDevice, > req: &mut uapi::drm_nova_gem_create, > file: &drm::File, > ) -> Result { > @@ -56,7 +60,7 @@ pub(crate) fn gem_create( > =20 > /// IOCTL: gem_info: Query GEM metadata. > pub(crate) fn gem_info( > - _dev: &NovaDevice, > + _dev: &NovaDevice, > req: &mut uapi::drm_nova_gem_info, > file: &drm::File, > ) -> Result { > diff --git a/drivers/gpu/drm/tyr/file.rs b/drivers/gpu/drm/tyr/file.rs > index 31411da203c5..fb9233eae01c 100644 > --- a/drivers/gpu/drm/tyr/file.rs > +++ b/drivers/gpu/drm/tyr/file.rs > @@ -1,7 +1,10 @@ > // SPDX-License-Identifier: GPL-2.0 or MIT > =20 > use kernel::{ > - drm, > + drm::{ > + self, > + Registered, // > + }, > prelude::*, > uaccess::UserSlice, > uapi, // > @@ -28,7 +31,7 @@ fn open(_dev: &drm::Device) -> Result>> { > =20 > impl TyrDrmFileData { > pub(crate) fn dev_query( > - ddev: &TyrDrmDevice, > + ddev: &TyrDrmDevice, > devquery: &mut uapi::drm_panthor_dev_query, > _file: &TyrDrmFile, > ) -> Result { > diff --git a/rust/kernel/drm/ioctl.rs b/rust/kernel/drm/ioctl.rs > index 6f5a9877bdae..f24cf7b146a8 100644 > --- a/rust/kernel/drm/ioctl.rs > +++ b/rust/kernel/drm/ioctl.rs > @@ -70,6 +70,18 @@ pub mod internal { > pub use bindings::drm_device; > pub use bindings::drm_file; > pub use bindings::drm_ioctl_desc; > + > + /// Reinterpret a pointer to a DRM device with a different [`DeviceC= ontext`], preserving the This sentence makes it sound like the origin and destination contexts are parameters, but this helper only does `Ioctl` to `Registered`. > + /// driver type parameter `T`. > + /// > + /// Used by [`declare_drm_ioctls!`] to anchor type inference. > + #[doc(hidden)] > + #[inline] > + pub const fn __dev_ctx_cast( > + ptr: *const crate::drm::Device, > + ) -> *const crate::drm::Device { > + ptr.cast() > + } > } The points above really are nits though. Reviewed-by: Alexandre Courbot