[PATCH v5 18/19] rust: drm: Pass registration data to ioctl handlers

[Danilo Krummrich]

Pass registration data to ioctl handlers via
drm::Device<Registered>::registration_data_with(). The closure's HRTB
ties the lifetime to the closure scope, and the pointer cast shortens it
from 'static internally. The reference is valid for the duration of the
drm_dev_enter/exit critical section held by RegistrationGuard.

Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 drivers/gpu/drm/nova/file.rs | 3 +++
 drivers/gpu/drm/tyr/file.rs  | 1 +
 rust/kernel/drm/ioctl.rs     | 8 ++++++--
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nova/file.rs b/drivers/gpu/drm/nova/file.rs
index 19fb89b28984..208be4e38188 100644
--- a/drivers/gpu/drm/nova/file.rs
+++ b/drivers/gpu/drm/nova/file.rs
@@ -28,6 +28,7 @@ impl File {
     /// IOCTL: get_param: Query GPU / driver metadata.
     pub(crate) fn get_param(
         dev: &NovaDevice<Registered>,
+        _reg_data: &(),
         getparam: &mut uapi::drm_nova_getparam,
         _file: &drm::File<File>,
     ) -> Result<u32> {
@@ -48,6 +49,7 @@ pub(crate) fn get_param(
     /// IOCTL: gem_create: Create a new DRM GEM object.
     pub(crate) fn gem_create(
         dev: &NovaDevice<Registered>,
+        _reg_data: &(),
         req: &mut uapi::drm_nova_gem_create,
         file: &drm::File<File>,
     ) -> Result<u32> {
@@ -61,6 +63,7 @@ pub(crate) fn gem_create(
     /// IOCTL: gem_info: Query GEM metadata.
     pub(crate) fn gem_info(
         _dev: &NovaDevice<Registered>,
+        _reg_data: &(),
         req: &mut uapi::drm_nova_gem_info,
         file: &drm::File<File>,
     ) -> Result<u32> {
diff --git a/drivers/gpu/drm/tyr/file.rs b/drivers/gpu/drm/tyr/file.rs
index fb9233eae01c..b686041d5d6b 100644
--- a/drivers/gpu/drm/tyr/file.rs
+++ b/drivers/gpu/drm/tyr/file.rs
@@ -32,6 +32,7 @@ fn open(_dev: &drm::Device<Self::Driver>) -> Result<Pin<KBox<Self>>> {
 impl TyrDrmFileData {
     pub(crate) fn dev_query(
         ddev: &TyrDrmDevice<Registered>,
+        _reg_data: &(),
         devquery: &mut uapi::drm_panthor_dev_query,
         _file: &TyrDrmFile,
     ) -> Result<u32> {
diff --git a/rust/kernel/drm/ioctl.rs b/rust/kernel/drm/ioctl.rs
index f24cf7b146a8..9b45b741db1b 100644
--- a/rust/kernel/drm/ioctl.rs
+++ b/rust/kernel/drm/ioctl.rs
@@ -95,6 +95,7 @@ pub const fn __dev_ctx_cast<T: crate::drm::Driver>(
 ///
 /// ```ignore
 /// fn foo(device: &kernel::drm::Device<Self, kernel::drm::Registered>,
+///        reg_data: &Self::RegistrationData<'_>,
 ///        data: &mut uapi::argument_type,
 ///        file: &kernel::drm::File<Self::File>,
 /// ) -> Result<u32>
@@ -169,13 +170,14 @@ macro_rules! declare_drm_ioctls {
                                     unsafe { &*__ptr },
                                     unreachable!(),
                                     unreachable!(),
+                                    unreachable!(),
                                 )
                             };
 
                             // Enforce that the handler accepts higher-ranked
                             // lifetimes, preventing it from requiring 'static
                             // references that could escape this scope.
-                            let _: for<'a> fn(&'a _, &'a mut _, &'a _) -> _ = $func;
+                            let _: for<'a> fn(&'a _, &'a _, &'a mut _, &'a _) -> _ = $func;
 
                             let Some(guard) = dev.registration_guard() else {
                                 return $crate::error::code::ENODEV.to_errno();
@@ -193,7 +195,9 @@ macro_rules! declare_drm_ioctls {
                             // SAFETY: This is just the DRM file structure
                             let file = unsafe { $crate::drm::File::from_raw(raw_file) };
 
-                            match $func(&*guard, data, file) {
+                            match guard.registration_data_with(|reg_data| {
+                                $func(&*guard, reg_data, data, file)
+                            }) {
                                 Err(e) => e.to_errno(),
                                 Ok(i) => i.try_into()
                                             .unwrap_or($crate::error::code::ERANGE.to_errno()),
-- 
2.54.0