1 // SPDX-License-Identifier: GPL-2.0 2 3 use super::HasHrTimer; 4 use super::HrTimer; 5 use super::HrTimerCallback; 6 use super::HrTimerHandle; 7 use super::HrTimerMode; 8 use super::RawHrTimerCallback; 9 use super::UnsafeHrTimerPointer; 10 use core::pin::Pin; 11 12 /// A handle for a `Pin<&HasHrTimer>`. When the handle exists, the timer might be 13 /// running. 14 pub struct PinHrTimerHandle<'a, T> 15 where 16 T: HasHrTimer<T>, 17 { 18 pub(crate) inner: Pin<&'a T>, 19 } 20 21 // SAFETY: We cancel the timer when the handle is dropped. The implementation of 22 // the `cancel` method will block if the timer handler is running. 23 unsafe impl<'a, T> HrTimerHandle for PinHrTimerHandle<'a, T> 24 where 25 T: HasHrTimer<T>, 26 { cancel(&mut self) -> bool27 fn cancel(&mut self) -> bool { 28 let self_ptr: *const T = self.inner.get_ref(); 29 30 // SAFETY: As we got `self_ptr` from a reference above, it must point to 31 // a valid `T`. 32 let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) }; 33 34 // SAFETY: As `timer_ptr` is derived from a reference, it must point to 35 // a valid and initialized `HrTimer`. 36 unsafe { HrTimer::<T>::raw_cancel(timer_ptr) } 37 } 38 } 39 40 impl<'a, T> Drop for PinHrTimerHandle<'a, T> 41 where 42 T: HasHrTimer<T>, 43 { drop(&mut self)44 fn drop(&mut self) { 45 self.cancel(); 46 } 47 } 48 49 // SAFETY: We capture the lifetime of `Self` when we create a `PinHrTimerHandle`, 50 // so `Self` will outlive the handle. 51 unsafe impl<'a, T> UnsafeHrTimerPointer for Pin<&'a T> 52 where 53 T: Send + Sync, 54 T: HasHrTimer<T>, 55 T: HrTimerCallback<Pointer<'a> = Self>, 56 { 57 type TimerMode = <T as HasHrTimer<T>>::TimerMode; 58 type TimerHandle = PinHrTimerHandle<'a, T>; 59 start( self, expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires, ) -> Self::TimerHandle60 unsafe fn start( 61 self, 62 expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires, 63 ) -> Self::TimerHandle { 64 // Cast to pointer 65 let self_ptr: *const T = self.get_ref(); 66 67 // SAFETY: 68 // - As we derive `self_ptr` from a reference above, it must point to a 69 // valid `T`. 70 // - We keep `self` alive by wrapping it in a handle below. 71 unsafe { T::start(self_ptr, expires) }; 72 73 PinHrTimerHandle { inner: self } 74 } 75 } 76 77 impl<'a, T> RawHrTimerCallback for Pin<&'a T> 78 where 79 T: HasHrTimer<T>, 80 T: HrTimerCallback<Pointer<'a> = Self>, 81 { 82 type CallbackTarget<'b> = Self; 83 run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart84 unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart { 85 // `HrTimer` is `repr(C)` 86 let timer_ptr = ptr.cast::<HrTimer<T>>(); 87 88 // SAFETY: By the safety requirement of this function, `timer_ptr` 89 // points to a `HrTimer<T>` contained in an `T`. 90 let receiver_ptr = unsafe { T::timer_container_of(timer_ptr) }; 91 92 // SAFETY: 93 // - By the safety requirement of this function, `timer_ptr` 94 // points to a `HrTimer<T>` contained in an `T`. 95 // - As per the safety requirements of the trait `HrTimerHandle`, the 96 // `PinHrTimerHandle` associated with this timer is guaranteed to 97 // be alive until this method returns. That handle borrows the `T` 98 // behind `receiver_ptr`, thus guaranteeing the validity of 99 // the reference created below. 100 let receiver_ref = unsafe { &*receiver_ptr }; 101 102 // SAFETY: `receiver_ref` only exists as pinned, so it is safe to pin it 103 // here. 104 let receiver_pin = unsafe { Pin::new_unchecked(receiver_ref) }; 105 106 T::run(receiver_pin).into_c() 107 } 108 } 109