// SPDX-License-Identifier: GPL-2.0
use super::HasHrTimer;
use super::HrTimer;
use super::HrTimerCallback;
use super::HrTimerHandle;
use super::HrTimerMode;
use super::HrTimerPointer;
use super::RawHrTimerCallback;
use crate::prelude::*;
use core::ptr::NonNull;
/// A handle for a [`Box<HasHrTimer<T>>`] returned by a call to
/// [`HrTimerPointer::start`].
///
/// # Invariants
///
/// - `self.inner` comes from a `Box::into_raw` call.
pub struct BoxHrTimerHandle<T, A>
where
T: HasHrTimer<T>,
A: crate::alloc::Allocator,
{
pub(crate) inner: NonNull<T>,
_p: core::marker::PhantomData<A>,
}
// SAFETY: We implement drop below, and we cancel the timer in the drop
// implementation.
unsafe impl<T, A> HrTimerHandle for BoxHrTimerHandle<T, A>
where
T: HasHrTimer<T>,
A: crate::alloc::Allocator,
{
fn cancel(&mut self) -> bool {
// SAFETY: As we obtained `self.inner` from a valid reference when we
// created `self`, it must point to a valid `T`.
let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self.inner.as_ptr()) };
// SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr`
// must point to a valid `HrTimer` instance.
unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
}
}
impl<T, A> Drop for BoxHrTimerHandle<T, A>
where
T: HasHrTimer<T>,
A: crate::alloc::Allocator,
{
fn drop(&mut self) {
self.cancel();
// SAFETY: By type invariant, `self.inner` came from a `Box::into_raw`
// call.
drop(unsafe { Box::<T, A>::from_raw(self.inner.as_ptr()) })
}
}
impl<T, A> HrTimerPointer for Pin<Box<T, A>>
where
T: 'static,
T: Send + Sync,
T: HasHrTimer<T>,
T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>,
A: crate::alloc::Allocator,
{
type TimerMode = <T as HasHrTimer<T>>::TimerMode;
type TimerHandle = BoxHrTimerHandle<T, A>;
fn start(
self,
expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
) -> Self::TimerHandle {
// SAFETY:
// - We will not move out of this box during timer callback (we pass an
// immutable reference to the callback).
// - `Box::into_raw` is guaranteed to return a valid pointer.
let inner =
unsafe { NonNull::new_unchecked(Box::into_raw(Pin::into_inner_unchecked(self))) };
// SAFETY:
// - We keep `self` alive by wrapping it in a handle below.
// - Since we generate the pointer passed to `start` from a valid
// reference, it is a valid pointer.
unsafe { T::start(inner.as_ptr(), expires) };
// INVARIANT: `inner` came from `Box::into_raw` above.
BoxHrTimerHandle {
inner,
_p: core::marker::PhantomData,
}
}
}
impl<T, A> RawHrTimerCallback for Pin<Box<T, A>>
where
T: 'static,
T: HasHrTimer<T>,
T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>,
A: crate::alloc::Allocator,
{
type CallbackTarget<'a> = Pin<&'a mut T>;
unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
// `HrTimer` is `repr(C)`
let timer_ptr = ptr.cast::<super::HrTimer<T>>();
// SAFETY: By C API contract `ptr` is the pointer we passed when
// queuing the timer, so it is a `HrTimer<T>` embedded in a `T`.
let data_ptr = unsafe { T::timer_container_of(timer_ptr) };
// SAFETY:
// - As per the safety requirements of the trait `HrTimerHandle`, the
// `BoxHrTimerHandle` associated with this timer is guaranteed to
// be alive until this method returns. That handle owns the `T`
// behind `data_ptr` thus guaranteeing the validity of
// the reference created below.
// - As `data_ptr` comes from a `Pin<Box<T>>`, only pinned references to
// `data_ptr` exist.
let data_mut_ref = unsafe { Pin::new_unchecked(&mut *data_ptr) };
T::run(data_mut_ref).into_c()
}
}
