kernel/drm/
file.rs

1// SPDX-License-Identifier: GPL-2.0 OR MIT
2
3//! DRM File objects.
4//!
5//! C header: [`include/drm/drm_file.h`](srctree/include/drm/drm_file.h)
6
7use crate::{
8    bindings,
9    drm,
10    prelude::*,
11    types::Opaque, //
12};
13use core::marker::PhantomData;
14
15/// Trait that must be implemented by DRM drivers to represent a DRM File (a client instance).
16pub trait DriverFile {
17    /// The parent `Driver` implementation for this `DriverFile`.
18    type Driver: drm::Driver;
19
20    /// Open a new file (called when a client opens the DRM device).
21    fn open(device: &drm::Device<Self::Driver>) -> Result<Pin<KBox<Self>>>;
22}
23
24/// An open DRM File.
25///
26/// # Invariants
27///
28/// `self.0` is a valid instance of a `struct drm_file`.
29#[repr(transparent)]
30pub struct File<T: DriverFile>(Opaque<bindings::drm_file>, PhantomData<T>);
31
32impl<T: DriverFile> File<T> {
33    #[doc(hidden)]
34    /// Not intended to be called externally, except via declare_drm_ioctls!()
35    ///
36    /// # Safety
37    ///
38    /// `raw_file` must be a valid pointer to an open `struct drm_file`, opened through `T::open`.
39    pub unsafe fn from_raw<'a>(ptr: *mut bindings::drm_file) -> &'a File<T> {
40        // SAFETY: `raw_file` is valid by the safety requirements of this function.
41        unsafe { &*ptr.cast() }
42    }
43
44    pub(super) fn as_raw(&self) -> *mut bindings::drm_file {
45        self.0.get()
46    }
47
48    fn driver_priv(&self) -> *mut T {
49        // SAFETY: By the type invariants of `Self`, `self.as_raw()` is always valid.
50        unsafe { (*self.as_raw()).driver_priv }.cast()
51    }
52
53    /// Return a pinned reference to the driver file structure.
54    pub fn inner(&self) -> Pin<&T> {
55        // SAFETY: By the type invariant the pointer `self.as_raw()` points to a valid and opened
56        // `struct drm_file`, hence `driver_priv` has been properly initialized by `open_callback`.
57        unsafe { Pin::new_unchecked(&*(self.driver_priv())) }
58    }
59
60    /// The open callback of a `struct drm_file`.
61    pub(crate) extern "C" fn open_callback(
62        raw_dev: *mut bindings::drm_device,
63        raw_file: *mut bindings::drm_file,
64    ) -> core::ffi::c_int {
65        // SAFETY: A callback from `struct drm_driver::open` guarantees that
66        // - `raw_dev` is valid pointer to a `struct drm_device`,
67        // - the corresponding `struct drm_device` has been registered.
68        let drm = unsafe { drm::Device::from_raw(raw_dev) };
69
70        // SAFETY: `raw_file` is a valid pointer to a `struct drm_file`.
71        let file = unsafe { File::<T>::from_raw(raw_file) };
72
73        let inner = match T::open(drm) {
74            Err(e) => {
75                return e.to_errno();
76            }
77            Ok(i) => i,
78        };
79
80        // SAFETY: This pointer is treated as pinned, and the Drop guarantee is upheld in
81        // `postclose_callback()`.
82        let driver_priv = KBox::into_raw(unsafe { Pin::into_inner_unchecked(inner) });
83
84        // SAFETY: By the type invariants of `Self`, `self.as_raw()` is always valid.
85        unsafe { (*file.as_raw()).driver_priv = driver_priv.cast() };
86
87        0
88    }
89
90    /// The postclose callback of a `struct drm_file`.
91    pub(crate) extern "C" fn postclose_callback(
92        _raw_dev: *mut bindings::drm_device,
93        raw_file: *mut bindings::drm_file,
94    ) {
95        // SAFETY: This reference won't escape this function
96        let file = unsafe { File::<T>::from_raw(raw_file) };
97
98        // SAFETY: `file.driver_priv` has been created in `open_callback` through `KBox::into_raw`.
99        let _ = unsafe { KBox::from_raw(file.driver_priv()) };
100    }
101}
102
103impl<T: DriverFile> super::private::Sealed for File<T> {}
kernel/drm/file.rs

kernel/drm/
file.rs
