From 4656b43c8e623d8b40ff253e4722623f1e342f0e Mon Sep 17 00:00:00 2001
From: Lyude Paul <lyude@redhat.com>
Date: Tue, 16 Jul 2024 17:31:37 -0400
Subject: [PATCH] squash! rust: hrtimer: Add Timer::cancel()
* I totally forgot that we actually need to both add a callback for
handling cleaning up a timer that didn't execute as a result of being
cancelled
---
rust/kernel/hrtimer.rs | 48 ++++++++++++++++++++++++++++++++++++------
1 file changed, 42 insertions(+), 6 deletions(-)
diff --git a/rust/kernel/hrtimer.rs b/rust/kernel/hrtimer.rs
index c93dcc224330a..b0d7c25e8ccbd 100644
--- a/rust/kernel/hrtimer.rs
+++ b/rust/kernel/hrtimer.rs
@@ -55,7 +55,7 @@
//!
//! C header: [`include/linux/hrtimer.h`](srctree/include/linux/hrtimer.h)
-use core::{marker::PhantomData, pin::Pin};
+use core::{marker::PhantomData, pin::Pin, ptr::{self, NonNull}};
use crate::{init::PinInit, prelude::*, sync::Arc, types::Opaque};
@@ -110,11 +110,28 @@ impl<T: TimerCallback> Timer<T> {
/// Cancel a timer and wait for its callback to finish executing
///
/// Returns `true` if the timer was active.
- pub fn cancel(&self) -> bool {
- // SAFETY: By struct invariant `self.timer` was initialized by
- // `hrtimer_init` so by C API contract it is safe to call
- // `hrtimer_cancel`.
- unsafe { bindings::hrtimer_cancel(self.timer.get()) != 0 }
+ pub fn cancel(&self) -> bool
+ where
+ T: HasTimer<T>
+ {
+ let timer_ptr = self.timer.get();
+
+ // SAFETY: By struct invariant `self.timer` was initialized by `hrtimer_init` so by C API
+ // contract it is safe to call `hrtimer_cancel`.
+ let cancelled = unsafe { bindings::hrtimer_cancel(timer_ptr) != 0 };
+
+ // If the callback cancelled before execution, cleanup its resources
+ if cancelled {
+ // SAFETY: `timer` is valid for as long as our interface is exposed
+ let data_ptr = unsafe {
+ NonNull::new_unchecked(T::timer_container_of(timer_ptr.cast()))
+ };
+
+ // SAFETY: We're in the `hrtimer` crate
+ unsafe { <T::Receiver as RawTimer>::cleanup(data_ptr) };
+ }
+
+ cancelled
}
/// Return the current time from the base timer for this timer
@@ -153,6 +170,16 @@ impl<T> PinnedDrop for Timer<T> {
pub trait RawTimer: Sync {
/// Schedule the timer after `expires` time units
fn schedule(self, expires: u64);
+
+ /// Cleanup resources for the timer if it was cancelled before executing
+ ///
+ /// # Safety
+ ///
+ /// This should only be called by the [`kernel::hrtimer`] crate
+ unsafe fn cleanup<T>(data: ptr::NonNull<T>)
+ where
+ Self: Sized + RawTimerCallback,
+ T: TimerCallback<Receiver = Self>;
}
/// Implemented by structs that contain timer nodes.
@@ -283,6 +310,15 @@ where
);
}
}
+
+ unsafe fn cleanup<D>(data: ptr::NonNull<D>)
+ where
+ Self: Sized + RawTimerCallback,
+ D: TimerCallback<Receiver = Self>
+ {
+ // SAFETY: The caller guarantees that `self` points to a valid instance of `Arc<T>`
+ drop(unsafe { Arc::from_raw(data.as_ptr()) })
+ }
}
impl<T> kernel::hrtimer::RawTimerCallback for Arc<T>
--
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