Add debugfs_init method to the Driver trait, enabling Rust DRM drivers to populate debugfs entries during device registration.
Signed-off-by: Alvin Sun <[email protected]> --- rust/kernel/drm/device.rs | 41 ++++++++++++++++++++++++++++++++++++++++- rust/kernel/drm/driver.rs | 11 +++++++++++ 2 files changed, 51 insertions(+), 1 deletion(-) diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs index 7a3a0e21e9557..35fd514fec274 100644 --- a/rust/kernel/drm/device.rs +++ b/rust/kernel/drm/device.rs @@ -7,6 +7,7 @@ use crate::{ alloc::allocator::Kmalloc, bindings, + debugfs, device, drm::{ self, @@ -170,7 +171,7 @@ const fn compute_features() -> u32 { release: Some(Device::<T>::release), master_set: None, master_drop: None, - debugfs_init: None, + debugfs_init: Some(Device::<T>::debugfs_init_callback), gem_create_object: T::Object::ALLOC_OPS.gem_create_object, prime_handle_to_fd: T::Object::ALLOC_OPS.prime_handle_to_fd, @@ -353,6 +354,44 @@ extern "C" fn release(ptr: *mut bindings::drm_device) { unsafe { core::ptr::drop_in_place(this) }; } + /// C callback for `drm_driver.debugfs_init`. + /// + /// # Safety + /// + /// The DRM core guarantees that `minor` is valid and non-null, that + /// `minor->dev` is a valid `drm_device` embedded in a `Device<T>`. + unsafe extern "C" fn debugfs_init_callback(minor: *mut bindings::drm_minor) { + // SAFETY: `minor` is valid and non-null per the function's safety + // precondition. + let dev_ptr = unsafe { (*minor).dev }; + // SAFETY: `minor` is valid per the function's safety precondition. + let debugfs_root = unsafe { (*minor).debugfs_root }; + + // Debugfs may be disabled. + if debugfs_root.is_null() { + return; + } + + // SAFETY: `dev_ptr` points to a valid `drm_device` embedded in + // `Device<T>`. + let dev = unsafe { Self::from_raw(dev_ptr) }; + + // SAFETY: The device is in the registered state per the function's + // safety precondition. + let dev = unsafe { dev.assume_ctx::<Registered>() }; + + dev.registration_data_with(|reg_data| { + // SAFETY: `debugfs_root` is valid as long as the DRM device is + // registered. The debugfs proxy fops wait for in-progress file + // operations and block new ones during `debugfs_remove()`, so no + // access to `reg_data` can outlive it. `debugfs_remove()` runs + // before `Registration::drop` frees `reg_data`. + let dir = unsafe { debugfs::ScopeRef::new(debugfs_root, reg_data) }; + + T::debugfs_init(&dir); + }); + } + /// Change the [`DeviceContext`] for a [`Device`]. /// /// # Safety diff --git a/rust/kernel/drm/driver.rs b/rust/kernel/drm/driver.rs index 08b2a318cf02a..f850b11fd5c53 100644 --- a/rust/kernel/drm/driver.rs +++ b/rust/kernel/drm/driver.rs @@ -6,6 +6,7 @@ use crate::{ bindings, + debugfs, device, drm, error::to_result, @@ -138,6 +139,16 @@ pub trait Driver { /// usable from the render node (i.e. marked DRM_RENDER_ALLOW), whereas /// userspace processes using the master node can invoke any ioctl. const FEAT_RENDER: bool = false; + + /// Populates debugfs for this DRM device. + /// + /// Called by the DRM core during registration. The `ScopeRef` provides + /// access to the device's `RegistrationData` for creating debugfs files. + fn debugfs_init(_dir: &debugfs::ScopeRef<'_, Self::RegistrationData<'_>>) + where + Self: Sized, + { + } } /// The registration type of a `drm::Device`. -- 2.43.0
