// SPDX-License-Identifier: GPL-2.0
use super::{
HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, HrTimerMode, RawHrTimerCallback,
UnsafeHrTimerPointer,
};
use core::{marker::PhantomData, pin::Pin, ptr::NonNull};
/// A handle for a `Pin<&mut HasHrTimer>`. When the handle exists, the timer might
/// be running.
pub struct PinMutHrTimerHandle<'a, T>
where
T: HasHrTimer<T>,
{
pub(crate) inner: NonNull<T>,
_p: PhantomData<&'a mut T>,
}
// SAFETY: We cancel the timer when the handle is dropped. The implementation of
// the `cancel` method will block if the timer handler is running.
unsafe impl<'a, T> HrTimerHandle for PinMutHrTimerHandle<'a, T>
where
T: HasHrTimer<T>,
{
fn cancel(&mut self) -> bool {
let self_ptr = self.inner.as_ptr();
// SAFETY: As we got `self_ptr` from a reference above, it must point to
// a valid `T`.
let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
// SAFETY: As `timer_ptr` is derived from a reference, it must point to
// a valid and initialized `HrTimer`.
unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
}
}
impl<'a, T> Drop for PinMutHrTimerHandle<'a, T>
where
T: HasHrTimer<T>,
{
fn drop(&mut self) {
self.cancel();
}
}
// SAFETY: We capture the lifetime of `Self` when we create a
// `PinMutHrTimerHandle`, so `Self` will outlive the handle.
unsafe impl<'a, T> UnsafeHrTimerPointer for Pin<&'a mut T>
where
T: Send + Sync,
T: HasHrTimer<T>,
T: HrTimerCallback<Pointer<'a> = Self>,
{
type TimerMode = <T as HasHrTimer<T>>::TimerMode;
type TimerHandle = PinMutHrTimerHandle<'a, T>;
unsafe fn start(
mut self,
expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
) -> Self::TimerHandle {
// SAFETY:
// - We promise not to move out of `self`. We only pass `self`
// back to the caller as a `Pin<&mut self>`.
// - The return value of `get_unchecked_mut` is guaranteed not to be null.
let self_ptr = unsafe { NonNull::new_unchecked(self.as_mut().get_unchecked_mut()) };
// SAFETY:
// - As we derive `self_ptr` from a reference above, it must point to a
// valid `T`.
// - We keep `self` alive by wrapping it in a handle below.
unsafe { T::start(self_ptr.as_ptr(), expires) };
PinMutHrTimerHandle {
inner: self_ptr,
_p: PhantomData,
}
}
}
impl<'a, T> RawHrTimerCallback for Pin<&'a mut T>
where
T: HasHrTimer<T>,
T: HrTimerCallback<Pointer<'a> = Self>,
{
type CallbackTarget<'b> = Self;
unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
// `HrTimer` is `repr(C)`
let timer_ptr = ptr.cast::<HrTimer<T>>();
// SAFETY: By the safety requirement of this function, `timer_ptr`
// points to a `HrTimer<T>` contained in an `T`.
let receiver_ptr = unsafe { T::timer_container_of(timer_ptr) };
// SAFETY:
// - By the safety requirement of this function, `timer_ptr`
// points to a `HrTimer<T>` contained in an `T`.
// - As per the safety requirements of the trait `HrTimerHandle`, the
// `PinMutHrTimerHandle` associated with this timer is guaranteed to
// be alive until this method returns. That handle borrows the `T`
// behind `receiver_ptr` mutably thus guaranteeing the validity of
// the reference created below.
let receiver_ref = unsafe { &mut *receiver_ptr };
// SAFETY: `receiver_ref` only exists as pinned, so it is safe to pin it
// here.
let receiver_pin = unsafe { Pin::new_unchecked(receiver_ref) };
T::run(receiver_pin).into_c()
}
}
