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e0c0ab04f6
Add a `TimerMode` associated type to the `HasHrTimer` trait to
represent the operational mode of the timer, such as absolute or
relative expiration. This new type must implement the `HrTimerMode`
trait, which defines how expiration values are interpreted.
Update the `start()` method to accept an `expires` parameter of type
`<Self::TimerMode as HrTimerMode>::Expires` instead of the fixed `Ktime`.
This enables different timer modes to provide strongly typed expiration
values, such as `Instant<C>` or `Delta`.
The `impl_has_hr_timer` macro is also extended to allow specifying the
`HrTimerMode`. In the following example, it guarantees that the
`start()` method for `Foo` only accepts `Instant<Monotonic>`. Using a
`Delta` or an `Instant` with a different clock source will result in a
compile-time error:
struct Foo {
#[pin]
timer: HrTimer<Self>,
}
impl_has_hr_timer! {
impl HasHrTimer<Self> for Foo {
mode : AbsoluteMode<Monotonic>,
field : self.timer
}
}
This design eliminates runtime mismatches between expires types and
clock sources, and enables stronger type-level guarantees throughout
hrtimer.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250610132823.3457263-5-fujita.tomonori@gmail.com
[ changed conversion method names to `as_*` - Andreas ]
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
104 lines
3.2 KiB
Rust
104 lines
3.2 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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use super::HasHrTimer;
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use super::HrTimer;
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use super::HrTimerCallback;
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use super::HrTimerHandle;
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use super::HrTimerMode;
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use super::HrTimerPointer;
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use super::RawHrTimerCallback;
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use crate::sync::Arc;
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use crate::sync::ArcBorrow;
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/// A handle for an `Arc<HasHrTimer<T>>` returned by a call to
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/// [`HrTimerPointer::start`].
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pub struct ArcHrTimerHandle<T>
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where
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T: HasHrTimer<T>,
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{
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pub(crate) inner: Arc<T>,
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}
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// SAFETY: We implement drop below, and we cancel the timer in the drop
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// implementation.
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unsafe impl<T> HrTimerHandle for ArcHrTimerHandle<T>
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where
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T: HasHrTimer<T>,
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{
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fn cancel(&mut self) -> bool {
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let self_ptr = Arc::as_ptr(&self.inner);
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// SAFETY: As we obtained `self_ptr` from a valid reference above, it
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// must point to a valid `T`.
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let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
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// SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr`
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// must point to a valid `HrTimer` instance.
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unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
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}
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}
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impl<T> Drop for ArcHrTimerHandle<T>
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where
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T: HasHrTimer<T>,
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{
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fn drop(&mut self) {
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self.cancel();
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}
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}
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impl<T> HrTimerPointer for Arc<T>
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where
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T: 'static,
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T: Send + Sync,
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T: HasHrTimer<T>,
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T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
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{
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type TimerMode = <T as HasHrTimer<T>>::TimerMode;
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type TimerHandle = ArcHrTimerHandle<T>;
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fn start(
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self,
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expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
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) -> ArcHrTimerHandle<T> {
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// SAFETY:
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// - We keep `self` alive by wrapping it in a handle below.
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// - Since we generate the pointer passed to `start` from a valid
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// reference, it is a valid pointer.
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unsafe { T::start(Arc::as_ptr(&self), expires) };
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ArcHrTimerHandle { inner: self }
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}
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}
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impl<T> RawHrTimerCallback for Arc<T>
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where
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T: 'static,
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T: HasHrTimer<T>,
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T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
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{
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type CallbackTarget<'a> = ArcBorrow<'a, T>;
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unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
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// `HrTimer` is `repr(C)`
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let timer_ptr = ptr.cast::<super::HrTimer<T>>();
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// SAFETY: By C API contract `ptr` is the pointer we passed when
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// queuing the timer, so it is a `HrTimer<T>` embedded in a `T`.
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let data_ptr = unsafe { T::timer_container_of(timer_ptr) };
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// SAFETY:
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// - `data_ptr` is derived form the pointer to the `T` that was used to
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// queue the timer.
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// - As per the safety requirements of the trait `HrTimerHandle`, the
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// `ArcHrTimerHandle` associated with this timer is guaranteed to
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// be alive until this method returns. That handle borrows the `T`
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// behind `data_ptr` thus guaranteeing the validity of
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// the `ArcBorrow` created below.
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// - We own one refcount in the `ArcTimerHandle` associated with this
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// timer, so it is not possible to get a `UniqueArc` to this
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// allocation from other `Arc` clones.
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let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
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T::run(receiver).into_c()
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}
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}
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