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::HrTimerPointer; 8 use super::Ktime; 9 use super::RawHrTimerCallback; 10 use crate::prelude::*; 11 use core::ptr::NonNull; 12 13 /// A handle for a [`Box<HasHrTimer<T>>`] returned by a call to 14 /// [`HrTimerPointer::start`]. 15 /// 16 /// # Invariants 17 /// 18 /// - `self.inner` comes from a `Box::into_raw` call. 19 pub struct BoxHrTimerHandle<T, A> 20 where 21 T: HasHrTimer<T>, 22 A: crate::alloc::Allocator, 23 { 24 pub(crate) inner: NonNull<T>, 25 _p: core::marker::PhantomData<A>, 26 } 27 28 // SAFETY: We implement drop below, and we cancel the timer in the drop 29 // implementation. 30 unsafe impl<T, A> HrTimerHandle for BoxHrTimerHandle<T, A> 31 where 32 T: HasHrTimer<T>, 33 A: crate::alloc::Allocator, 34 { cancel(&mut self) -> bool35 fn cancel(&mut self) -> bool { 36 // SAFETY: As we obtained `self.inner` from a valid reference when we 37 // created `self`, it must point to a valid `T`. 38 let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self.inner.as_ptr()) }; 39 40 // SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr` 41 // must point to a valid `HrTimer` instance. 42 unsafe { HrTimer::<T>::raw_cancel(timer_ptr) } 43 } 44 } 45 46 impl<T, A> Drop for BoxHrTimerHandle<T, A> 47 where 48 T: HasHrTimer<T>, 49 A: crate::alloc::Allocator, 50 { drop(&mut self)51 fn drop(&mut self) { 52 self.cancel(); 53 // SAFETY: By type invariant, `self.inner` came from a `Box::into_raw` 54 // call. 55 drop(unsafe { Box::<T, A>::from_raw(self.inner.as_ptr()) }) 56 } 57 } 58 59 impl<T, A> HrTimerPointer for Pin<Box<T, A>> 60 where 61 T: 'static, 62 T: Send + Sync, 63 T: HasHrTimer<T>, 64 T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>, 65 A: crate::alloc::Allocator, 66 { 67 type TimerHandle = BoxHrTimerHandle<T, A>; 68 start(self, expires: Ktime) -> Self::TimerHandle69 fn start(self, expires: Ktime) -> Self::TimerHandle { 70 // SAFETY: 71 // - We will not move out of this box during timer callback (we pass an 72 // immutable reference to the callback). 73 // - `Box::into_raw` is guaranteed to return a valid pointer. 74 let inner = 75 unsafe { NonNull::new_unchecked(Box::into_raw(Pin::into_inner_unchecked(self))) }; 76 77 // SAFETY: 78 // - We keep `self` alive by wrapping it in a handle below. 79 // - Since we generate the pointer passed to `start` from a valid 80 // reference, it is a valid pointer. 81 unsafe { T::start(inner.as_ptr(), expires) }; 82 83 // INVARIANT: `inner` came from `Box::into_raw` above. 84 BoxHrTimerHandle { 85 inner, 86 _p: core::marker::PhantomData, 87 } 88 } 89 } 90 91 impl<T, A> RawHrTimerCallback for Pin<Box<T, A>> 92 where 93 T: 'static, 94 T: HasHrTimer<T>, 95 T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>, 96 A: crate::alloc::Allocator, 97 { 98 type CallbackTarget<'a> = Pin<&'a mut T>; 99 run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart100 unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart { 101 // `HrTimer` is `repr(C)` 102 let timer_ptr = ptr.cast::<super::HrTimer<T>>(); 103 104 // SAFETY: By C API contract `ptr` is the pointer we passed when 105 // queuing the timer, so it is a `HrTimer<T>` embedded in a `T`. 106 let data_ptr = unsafe { T::timer_container_of(timer_ptr) }; 107 108 // SAFETY: 109 // - As per the safety requirements of the trait `HrTimerHandle`, the 110 // `BoxHrTimerHandle` associated with this timer is guaranteed to 111 // be alive until this method returns. That handle owns the `T` 112 // behind `data_ptr` thus guaranteeing the validity of 113 // the reference created below. 114 // - As `data_ptr` comes from a `Pin<Box<T>>`, only pinned references to 115 // `data_ptr` exist. 116 let data_mut_ref = unsafe { Pin::new_unchecked(&mut *data_ptr) }; 117 118 T::run(data_mut_ref).into_c() 119 } 120 } 121