Resguardo inicial

linux-7.2.3/rust/kernel/time/delay.rs

@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Delay and sleep primitives.
+//!
+//! This module contains the kernel APIs related to delay and sleep that
+//! have been ported or wrapped for usage by Rust code in the kernel.
+//!
+//! C header: [`include/linux/delay.h`](srctree/include/linux/delay.h).
+
+use super::Delta;
+use crate::prelude::*;
+
+/// Sleeps for a given duration at least.
+///
+/// Equivalent to the C side [`fsleep()`], flexible sleep function,
+/// which automatically chooses the best sleep method based on a duration.
+///
+/// `delta` must be within `[0, i32::MAX]` microseconds;
+/// otherwise, it is erroneous behavior. That is, it is considered a bug
+/// to call this function with an out-of-range value, in which case the function
+/// will sleep for at least the maximum value in the range and may warn
+/// in the future.
+///
+/// The behavior above differs from the C side [`fsleep()`] for which out-of-range
+/// values mean "infinite timeout" instead.
+///
+/// This function can only be used in a nonatomic context.
+///
+/// [`fsleep()`]: https://docs.kernel.org/timers/delay_sleep_functions.html#c.fsleep
+pub fn fsleep(delta: Delta) {
+    // The maximum value is set to `i32::MAX` microseconds to prevent integer
+    // overflow inside fsleep, which could lead to unintentional infinite sleep.
+    const MAX_DELTA: Delta = Delta::from_micros(i32::MAX as i64);
+
+    let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
+        delta
+    } else {
+        // TODO: Add WARN_ONCE() when it's supported.
+        MAX_DELTA
+    };
+
+    // SAFETY: It is always safe to call `fsleep()` with any duration.
+    unsafe {
+        // Convert the duration to microseconds and round up to preserve
+        // the guarantee; `fsleep()` sleeps for at least the provided duration,
+        // but that it may sleep for longer under some circumstances.
+        bindings::fsleep(delta.as_micros_ceil() as c_ulong)
+    }
+}
+
+/// Inserts a delay based on microseconds with busy waiting.
+///
+/// Equivalent to the C side [`udelay()`], which delays in microseconds.
+///
+/// `delta` must be within `[0, MAX_UDELAY_MS]` in milliseconds;
+/// otherwise, it is erroneous behavior. That is, it is considered a bug to
+/// call this function with an out-of-range value.
+///
+/// The behavior above differs from the C side [`udelay()`] for which out-of-range
+/// values could lead to an overflow and unexpected behavior.
+///
+/// [`udelay()`]: https://docs.kernel.org/timers/delay_sleep_functions.html#c.udelay
+pub fn udelay(delta: Delta) {
+    const MAX_UDELAY_DELTA: Delta = Delta::from_millis(bindings::MAX_UDELAY_MS as i64);
+
+    debug_assert!(delta.as_nanos() >= 0);
+    debug_assert!(delta <= MAX_UDELAY_DELTA);
+
+    let delta = if (Delta::ZERO..=MAX_UDELAY_DELTA).contains(&delta) {
+        delta
+    } else {
+        MAX_UDELAY_DELTA
+    };
+
+    // SAFETY: It is always safe to call `udelay()` with any duration.
+    // Note that the kernel is compiled with `-fno-strict-overflow`
+    // so any out-of-range value could lead to unexpected behavior
+    // but won't lead to undefined behavior.
+    unsafe {
+        // Convert the duration to microseconds and round up to preserve
+        // the guarantee; `udelay()` inserts a delay for at least
+        // the provided duration, but that it may delay for longer
+        // under some circumstances.
+        bindings::udelay(delta.as_micros_ceil() as c_ulong)
+    }
+}

linux-7.2.3/rust/kernel/time/hrtimer/arc.rs

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::HasHrTimer;
+use super::HrTimer;
+use super::HrTimerCallback;
+use super::HrTimerCallbackContext;
+use super::HrTimerHandle;
+use super::HrTimerMode;
+use super::HrTimerPointer;
+use super::RawHrTimerCallback;
+use crate::sync::Arc;
+use crate::sync::ArcBorrow;
+
+/// A handle for an `Arc<HasHrTimer<T>>` returned by a call to
+/// [`HrTimerPointer::start`].
+pub struct ArcHrTimerHandle<T>
+where
+    T: HasHrTimer<T>,
+{
+    pub(crate) inner: Arc<T>,
+}
+
+// SAFETY: We implement drop below, and we cancel the timer in the drop
+// implementation.
+unsafe impl<T> HrTimerHandle for ArcHrTimerHandle<T>
+where
+    T: HasHrTimer<T>,
+{
+    fn cancel(&mut self) -> bool {
+        let self_ptr = Arc::as_ptr(&self.inner);
+
+        // SAFETY: As we obtained `self_ptr` from a valid reference above, it
+        // must point to a valid `T`.
+        let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
+
+        // SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr`
+        // must point to a valid `HrTimer` instance.
+        unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
+    }
+}
+
+impl<T> Drop for ArcHrTimerHandle<T>
+where
+    T: HasHrTimer<T>,
+{
+    fn drop(&mut self) {
+        self.cancel();
+    }
+}
+
+impl<T> HrTimerPointer for Arc<T>
+where
+    T: 'static,
+    T: Send + Sync,
+    T: HasHrTimer<T>,
+    T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
+{
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
+    type TimerHandle = ArcHrTimerHandle<T>;
+
+    fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> ArcHrTimerHandle<T> {
+        // SAFETY:
+        //  - We keep `self` alive by wrapping it in a handle below.
+        //  - Since we generate the pointer passed to `start` from a valid
+        //    reference, it is a valid pointer.
+        unsafe { T::start(Arc::as_ptr(&self), expires) };
+        ArcHrTimerHandle { inner: self }
+    }
+}
+
+impl<T> RawHrTimerCallback for Arc<T>
+where
+    T: 'static,
+    T: HasHrTimer<T>,
+    T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
+{
+    type CallbackTarget<'a> = ArcBorrow<'a, T>;
+
+    unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
+        // `HrTimer` is `repr(C)`
+        let timer_ptr = ptr.cast::<super::HrTimer<T>>();
+
+        // SAFETY: By C API contract `ptr` is the pointer we passed when
+        // queuing the timer, so it is a `HrTimer<T>` embedded in a `T`.
+        let data_ptr = unsafe { T::timer_container_of(timer_ptr) };
+
+        // SAFETY:
+        //  - `data_ptr` is derived form the pointer to the `T` that was used to
+        //    queue the timer.
+        //  - As per the safety requirements of the trait `HrTimerHandle`, the
+        //    `ArcHrTimerHandle` associated with this timer is guaranteed to
+        //    be alive until this method returns. That handle borrows the `T`
+        //    behind `data_ptr` thus guaranteeing the validity of
+        //    the `ArcBorrow` created below.
+        //  - We own one refcount in the `ArcTimerHandle` associated with this
+        //    timer, so it is not possible to get a `UniqueArc` to this
+        //    allocation from other `Arc` clones.
+        let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
+
+        // SAFETY:
+        // - By C API contract `timer_ptr` is the pointer that we passed when queuing the timer, so
+        //   it is a valid pointer to a `HrTimer<T>` embedded in a `T`.
+        // - We are within `RawHrTimerCallback::run`
+        let context = unsafe { HrTimerCallbackContext::from_raw(timer_ptr) };
+
+        T::run(receiver, context).into_c()
+    }
+}

linux-7.2.3/rust/kernel/time/hrtimer/pin.rs

@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::HasHrTimer;
+use super::HrTimer;
+use super::HrTimerCallback;
+use super::HrTimerCallbackContext;
+use super::HrTimerHandle;
+use super::HrTimerMode;
+use super::RawHrTimerCallback;
+use super::UnsafeHrTimerPointer;
+use core::pin::Pin;
+
+/// A handle for a `Pin<&HasHrTimer>`. When the handle exists, the timer might be
+/// running.
+pub struct PinHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    pub(crate) inner: Pin<&'a T>,
+}
+
+// SAFETY: We cancel the timer when the handle is dropped. The implementation of
+// the `cancel` method will block if the timer handler is running.
+unsafe impl<'a, T> HrTimerHandle for PinHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    fn cancel(&mut self) -> bool {
+        let self_ptr: *const T = self.inner.get_ref();
+
+        // SAFETY: As we got `self_ptr` from a reference above, it must point to
+        // a valid `T`.
+        let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
+
+        // SAFETY: As `timer_ptr` is derived from a reference, it must point to
+        // a valid and initialized `HrTimer`.
+        unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
+    }
+}
+
+impl<'a, T> Drop for PinHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    fn drop(&mut self) {
+        self.cancel();
+    }
+}
+
+// SAFETY: We capture the lifetime of `Self` when we create a `PinHrTimerHandle`,
+// so `Self` will outlive the handle.
+unsafe impl<'a, T> UnsafeHrTimerPointer for Pin<&'a T>
+where
+    T: Send + Sync,
+    T: HasHrTimer<T>,
+    T: HrTimerCallback<Pointer<'a> = Self>,
+{
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
+    type TimerHandle = PinHrTimerHandle<'a, T>;
+
+    unsafe fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
+        // Cast to pointer
+        let self_ptr: *const T = self.get_ref();
+
+        // SAFETY:
+        //  - As we derive `self_ptr` from a reference above, it must point to a
+        //    valid `T`.
+        //  - We keep `self` alive by wrapping it in a handle below.
+        unsafe { T::start(self_ptr, expires) };
+
+        PinHrTimerHandle { inner: self }
+    }
+}
+
+impl<'a, T> RawHrTimerCallback for Pin<&'a T>
+where
+    T: HasHrTimer<T>,
+    T: HrTimerCallback<Pointer<'a> = Self>,
+{
+    type CallbackTarget<'b> = Self;
+
+    unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
+        // `HrTimer` is `repr(C)`
+        let timer_ptr = ptr.cast::<HrTimer<T>>();
+
+        // SAFETY: By the safety requirement of this function, `timer_ptr`
+        // points to a `HrTimer<T>` contained in an `T`.
+        let receiver_ptr = unsafe { T::timer_container_of(timer_ptr) };
+
+        // SAFETY:
+        //  - By the safety requirement of this function, `timer_ptr`
+        //    points to a `HrTimer<T>` contained in an `T`.
+        //  - As per the safety requirements of the trait `HrTimerHandle`, the
+        //    `PinHrTimerHandle` associated with this timer is guaranteed to
+        //    be alive until this method returns. That handle borrows the `T`
+        //    behind `receiver_ptr`, thus guaranteeing the validity of
+        //    the reference created below.
+        let receiver_ref = unsafe { &*receiver_ptr };
+
+        // SAFETY: `receiver_ref` only exists as pinned, so it is safe to pin it
+        // here.
+        let receiver_pin = unsafe { Pin::new_unchecked(receiver_ref) };
+
+        // SAFETY:
+        // - By C API contract `timer_ptr` is the pointer that we passed when queuing the timer, so
+        //   it is a valid pointer to a `HrTimer<T>` embedded in a `T`.
+        // - We are within `RawHrTimerCallback::run`
+        let context = unsafe { HrTimerCallbackContext::from_raw(timer_ptr) };
+
+        T::run(receiver_pin, context).into_c()
+    }
+}

linux-7.2.3/rust/kernel/time/hrtimer/pin_mut.rs

@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::{
+    HasHrTimer, HrTimer, HrTimerCallback, HrTimerCallbackContext, HrTimerHandle, HrTimerMode,
+    RawHrTimerCallback, UnsafeHrTimerPointer,
+};
+use core::{marker::PhantomData, pin::Pin, ptr::NonNull};
+
+/// A handle for a `Pin<&mut HasHrTimer>`. When the handle exists, the timer might
+/// be running.
+pub struct PinMutHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    pub(crate) inner: NonNull<T>,
+    _p: PhantomData<&'a mut T>,
+}
+
+// SAFETY: We cancel the timer when the handle is dropped. The implementation of
+// the `cancel` method will block if the timer handler is running.
+unsafe impl<'a, T> HrTimerHandle for PinMutHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    fn cancel(&mut self) -> bool {
+        let self_ptr = self.inner.as_ptr();
+
+        // SAFETY: As we got `self_ptr` from a reference above, it must point to
+        // a valid `T`.
+        let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
+
+        // SAFETY: As `timer_ptr` is derived from a reference, it must point to
+        // a valid and initialized `HrTimer`.
+        unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
+    }
+}
+
+impl<'a, T> Drop for PinMutHrTimerHandle<'a, T>
+where
+    T: HasHrTimer<T>,
+{
+    fn drop(&mut self) {
+        self.cancel();
+    }
+}
+
+// SAFETY: We capture the lifetime of `Self` when we create a
+// `PinMutHrTimerHandle`, so `Self` will outlive the handle.
+unsafe impl<'a, T> UnsafeHrTimerPointer for Pin<&'a mut T>
+where
+    T: Send + Sync,
+    T: HasHrTimer<T>,
+    T: HrTimerCallback<Pointer<'a> = Self>,
+{
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
+    type TimerHandle = PinMutHrTimerHandle<'a, T>;
+
+    unsafe fn start(
+        mut self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
+        // SAFETY:
+        // - We promise not to move out of `self`. We only pass `self`
+        //   back to the caller as a `Pin<&mut self>`.
+        // - The return value of `get_unchecked_mut` is guaranteed not to be null.
+        let self_ptr = unsafe { NonNull::new_unchecked(self.as_mut().get_unchecked_mut()) };
+
+        // SAFETY:
+        //  - As we derive `self_ptr` from a reference above, it must point to a
+        //    valid `T`.
+        //  - We keep `self` alive by wrapping it in a handle below.
+        unsafe { T::start(self_ptr.as_ptr(), expires) };
+
+        PinMutHrTimerHandle {
+            inner: self_ptr,
+            _p: PhantomData,
+        }
+    }
+}
+
+impl<'a, T> RawHrTimerCallback for Pin<&'a mut T>
+where
+    T: HasHrTimer<T>,
+    T: HrTimerCallback<Pointer<'a> = Self>,
+{
+    type CallbackTarget<'b> = Self;
+
+    unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
+        // `HrTimer` is `repr(C)`
+        let timer_ptr = ptr.cast::<HrTimer<T>>();
+
+        // SAFETY: By the safety requirement of this function, `timer_ptr`
+        // points to a `HrTimer<T>` contained in an `T`.
+        let receiver_ptr = unsafe { T::timer_container_of(timer_ptr) };
+
+        // SAFETY:
+        //  - By the safety requirement of this function, `timer_ptr`
+        //    points to a `HrTimer<T>` contained in an `T`.
+        //  - As per the safety requirements of the trait `HrTimerHandle`, the
+        //    `PinMutHrTimerHandle` associated with this timer is guaranteed to
+        //    be alive until this method returns. That handle borrows the `T`
+        //    behind `receiver_ptr` mutably thus guaranteeing the validity of
+        //    the reference created below.
+        let receiver_ref = unsafe { &mut *receiver_ptr };
+
+        // SAFETY: `receiver_ref` only exists as pinned, so it is safe to pin it
+        // here.
+        let receiver_pin = unsafe { Pin::new_unchecked(receiver_ref) };
+
+        // SAFETY:
+        // - By C API contract `timer_ptr` is the pointer that we passed when queuing the timer, so
+        //   it is a valid pointer to a `HrTimer<T>` embedded in a `T`.
+        // - We are within `RawHrTimerCallback::run`
+        let context = unsafe { HrTimerCallbackContext::from_raw(timer_ptr) };
+
+        T::run(receiver_pin, context).into_c()
+    }
+}

linux-7.2.3/rust/kernel/time/hrtimer/tbox.rs

@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::HasHrTimer;
+use super::HrTimer;
+use super::HrTimerCallback;
+use super::HrTimerCallbackContext;
+use super::HrTimerHandle;
+use super::HrTimerMode;
+use super::HrTimerPointer;
+use super::RawHrTimerCallback;
+use crate::prelude::*;
+use core::ptr::NonNull;
+
+/// A handle for a [`Box<HasHrTimer<T>>`] returned by a call to
+/// [`HrTimerPointer::start`].
+///
+/// # Invariants
+///
+/// - `self.inner` comes from a `Box::into_raw` call.
+pub struct BoxHrTimerHandle<T, A>
+where
+    T: HasHrTimer<T>,
+    A: crate::alloc::Allocator,
+{
+    pub(crate) inner: NonNull<T>,
+    _p: core::marker::PhantomData<A>,
+}
+
+// SAFETY: We implement drop below, and we cancel the timer in the drop
+// implementation.
+unsafe impl<T, A> HrTimerHandle for BoxHrTimerHandle<T, A>
+where
+    T: HasHrTimer<T>,
+    A: crate::alloc::Allocator,
+{
+    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 `T`.
+        let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self.inner.as_ptr()) };
+
+        // SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr`
+        // must point to a valid `HrTimer` instance.
+        unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
+    }
+}
+
+impl<T, A> Drop for BoxHrTimerHandle<T, A>
+where
+    T: HasHrTimer<T>,
+    A: crate::alloc::Allocator,
+{
+    fn drop(&mut self) {
+        self.cancel();
+        // SAFETY: By type invariant, `self.inner` came from a `Box::into_raw`
+        // call.
+        drop(unsafe { Box::<T, A>::from_raw(self.inner.as_ptr()) })
+    }
+}
+
+impl<T, A> HrTimerPointer for Pin<Box<T, A>>
+where
+    T: 'static,
+    T: Send + Sync,
+    T: HasHrTimer<T>,
+    T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>,
+    A: crate::alloc::Allocator,
+{
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
+    type TimerHandle = BoxHrTimerHandle<T, A>;
+
+    fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
+        // SAFETY:
+        //  - We will not move out of this box during timer callback (we pass an
+        //    immutable reference to the callback).
+        //  - `Box::into_raw` is guaranteed to return a valid pointer.
+        let inner =
+            unsafe { NonNull::new_unchecked(Box::into_raw(Pin::into_inner_unchecked(self))) };
+
+        // SAFETY:
+        //  - We keep `self` alive by wrapping it in a handle below.
+        //  - Since we generate the pointer passed to `start` from a valid
+        //    reference, it is a valid pointer.
+        unsafe { T::start(inner.as_ptr(), expires) };
+
+        // INVARIANT: `inner` came from `Box::into_raw` above.
+        BoxHrTimerHandle {
+            inner,
+            _p: core::marker::PhantomData,
+        }
+    }
+}
+
+impl<T, A> RawHrTimerCallback for Pin<Box<T, A>>
+where
+    T: 'static,
+    T: HasHrTimer<T>,
+    T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>,
+    A: crate::alloc::Allocator,
+{
+    type CallbackTarget<'a> = Pin<&'a mut T>;
+
+    unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
+        // `HrTimer` is `repr(C)`
+        let timer_ptr = ptr.cast::<super::HrTimer<T>>();
+
+        // SAFETY: By C API contract `ptr` is the pointer we passed when
+        // queuing the timer, so it is a `HrTimer<T>` embedded in a `T`.
+        let data_ptr = unsafe { T::timer_container_of(timer_ptr) };
+
+        // SAFETY:
+        //  - As per the safety requirements of the trait `HrTimerHandle`, the
+        //   `BoxHrTimerHandle` associated with this timer is guaranteed to
+        //   be alive until this method returns. That handle owns the `T`
+        //   behind `data_ptr` thus guaranteeing the validity of
+        //   the reference created below.
+        // - As `data_ptr` comes from a `Pin<Box<T>>`, only pinned references to
+        //   `data_ptr` exist.
+        let data_mut_ref = unsafe { Pin::new_unchecked(&mut *data_ptr) };
+
+        // SAFETY:
+        // - By C API contract `timer_ptr` is the pointer that we passed when queuing the timer, so
+        //   it is a valid pointer to a `HrTimer<T>` embedded in a `T`.
+        // - We are within `RawHrTimerCallback::run`
+        let context = unsafe { HrTimerCallbackContext::from_raw(timer_ptr) };
+
+        T::run(data_mut_ref, context).into_c()
+    }
+}