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Message-Id: <20241017-hrtimer-v3-v6-12-rc2-v3-10-59a75cbb44da@kernel.org>
Date: Thu, 17 Oct 2024 15:04:37 +0200
From: Andreas Hindborg <a.hindborg@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>,
Anna-Maria Behnsen <anna-maria@...utronix.de>,
Frederic Weisbecker <frederic@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>, Lyude Paul <lyude@...hat.com>,
rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
Andreas Hindborg <a.hindborg@...nel.org>
Subject: [PATCH v3 10/13] rust: hrtimer: implement `TimerPointer` for
`Pin<Box<T>>`
Allow `Pin<Box<T>>` to be the target of a timer callback.
Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
---
rust/kernel/hrtimer.rs | 3 ++
rust/kernel/hrtimer/tbox.rs | 95 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 98 insertions(+)
diff --git a/rust/kernel/hrtimer.rs b/rust/kernel/hrtimer.rs
index d8cea8b15a9afc134b10dc5703d88d70323fc943..2c1573e19576de93afc959d71e94173e2c1ed715 100644
--- a/rust/kernel/hrtimer.rs
+++ b/rust/kernel/hrtimer.rs
@@ -394,6 +394,9 @@ unsafe fn raw_get_timer(ptr: *const Self) ->
}
}
+// `box` is a reserved keyword, so prefix with `t` for timer
+mod tbox;
+
mod arc;
mod pin;
mod pin_mut;
diff --git a/rust/kernel/hrtimer/tbox.rs b/rust/kernel/hrtimer/tbox.rs
new file mode 100644
index 0000000000000000000000000000000000000000..b4199671d728c7f070b4ffb30a3cbc2635c0cb89
--- /dev/null
+++ b/rust/kernel/hrtimer/tbox.rs
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::HasTimer;
+use super::RawTimerCallback;
+use super::Timer;
+use super::TimerCallback;
+use super::TimerHandle;
+use super::TimerPointer;
+use crate::prelude::*;
+use crate::time::Ktime;
+use core::mem::ManuallyDrop;
+
+/// A handle for a `Box<HasTimer<U>>` returned by a call to
+/// [`TimerPointer::start`].
+pub struct BoxTimerHandle<U>
+where
+ U: HasTimer<U>,
+{
+ pub(crate) inner: *mut U,
+}
+
+// SAFETY: We implement drop below, and we cancel the timer in the drop
+// implementation.
+unsafe impl<U> TimerHandle for BoxTimerHandle<U>
+where
+ U: HasTimer<U>,
+{
+ fn cancel(&mut self) -> bool {
+ // SAFETY: As we obtained `self.inner` from a valid reference when we
+ // created `self`, it must point to a valid `U`.
+ let timer_ptr = unsafe { <U as HasTimer<U>>::raw_get_timer(self.inner) };
+
+ // SAFETY: As `timer_ptr` points into `U` and `U` is valid, `timer_ptr`
+ // must point to a valid `Timer` instance.
+ unsafe { Timer::<U>::raw_cancel(timer_ptr) }
+ }
+}
+
+impl<U> Drop for BoxTimerHandle<U>
+where
+ U: HasTimer<U>,
+{
+ fn drop(&mut self) {
+ self.cancel();
+ }
+}
+
+impl<U> TimerPointer for Pin<Box<U>>
+where
+ U: Send + Sync,
+ U: HasTimer<U>,
+ U: for<'a> TimerCallback<CallbackTarget<'a> = Pin<Box<U>>>,
+ U: for<'a> TimerCallback<CallbackTargetParameter<'a> = Pin<&'a U>>,
+{
+ type TimerHandle = BoxTimerHandle<U>;
+
+ fn start(self, expires: Ktime) -> Self::TimerHandle {
+ use core::ops::Deref;
+ let self_ptr = self.deref() as *const U;
+
+ // SAFETY: Since we generate the pointer passed to `start` from a valid
+ // reference, it is a valid pointer.
+ unsafe { U::start(self_ptr, expires) };
+
+ // SAFETY: We will not move out of this box during timer callback (we
+ // pass an immutable reference to the callback).
+ let inner = unsafe { Pin::into_inner_unchecked(self) };
+
+ BoxTimerHandle {
+ inner: Box::into_raw(inner),
+ }
+ }
+}
+
+impl<U> RawTimerCallback for Pin<Box<U>>
+where
+ U: HasTimer<U>,
+ U: for<'a> TimerCallback<CallbackTarget<'a> = Pin<Box<U>>>,
+ U: for<'a> TimerCallback<CallbackTargetParameter<'a> = Pin<&'a U>>,
+{
+ unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
+ // `Timer` is `repr(C)`
+ let timer_ptr = ptr.cast::<kernel::hrtimer::Timer<U>>();
+
+ // SAFETY: By C API contract `ptr` is the pointer we passed when
+ // queuing the timer, so it is a `Timer<T>` embedded in a `T`.
+ let data_ptr = unsafe { U::timer_container_of(timer_ptr) };
+
+ // SAFETY: We called `Box::into_raw` when we queued the timer.
+ let tbox = ManuallyDrop::new(Box::into_pin(unsafe { Box::from_raw(data_ptr) }));
+
+ use core::ops::Deref;
+ U::run(tbox.deref().as_ref()).into()
+ }
+}
--
2.46.0
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