diff options
Diffstat (limited to '')
| -rw-r--r-- | library/core/src/sync/atomic.rs | 134 | ||||
| -rw-r--r-- | library/core/src/sync/exclusive.rs | 9 |
2 files changed, 59 insertions, 84 deletions
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index 5e2e0c4d8..edc68d6fa 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -294,7 +294,7 @@ impl AtomicBool { /// ``` /// use std::sync::atomic::AtomicBool; /// - /// let atomic_true = AtomicBool::new(true); + /// let atomic_true = AtomicBool::new(true); /// let atomic_false = AtomicBool::new(false); /// ``` #[inline] @@ -955,6 +955,14 @@ impl AtomicBool { /// **Note:** This method is only available on platforms that support atomic /// operations on `u8`. /// + /// # Considerations + /// + /// This method is not magic; it is not provided by the hardware. + /// It is implemented in terms of [`AtomicBool::compare_exchange_weak`], and suffers from the same drawbacks. + /// In particular, this method will not circumvent the [ABA Problem]. + /// + /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem + /// /// # Examples /// /// ```rust @@ -1171,7 +1179,7 @@ impl<T> AtomicPtr<T> { /// use std::sync::atomic::{AtomicPtr, Ordering}; /// /// let ptr = &mut 5; - /// let some_ptr = AtomicPtr::new(ptr); + /// let some_ptr = AtomicPtr::new(ptr); /// /// let value = some_ptr.load(Ordering::Relaxed); /// ``` @@ -1198,7 +1206,7 @@ impl<T> AtomicPtr<T> { /// use std::sync::atomic::{AtomicPtr, Ordering}; /// /// let ptr = &mut 5; - /// let some_ptr = AtomicPtr::new(ptr); + /// let some_ptr = AtomicPtr::new(ptr); /// /// let other_ptr = &mut 10; /// @@ -1230,7 +1238,7 @@ impl<T> AtomicPtr<T> { /// use std::sync::atomic::{AtomicPtr, Ordering}; /// /// let ptr = &mut 5; - /// let some_ptr = AtomicPtr::new(ptr); + /// let some_ptr = AtomicPtr::new(ptr); /// /// let other_ptr = &mut 10; /// @@ -1282,9 +1290,9 @@ impl<T> AtomicPtr<T> { /// use std::sync::atomic::{AtomicPtr, Ordering}; /// /// let ptr = &mut 5; - /// let some_ptr = AtomicPtr::new(ptr); + /// let some_ptr = AtomicPtr::new(ptr); /// - /// let other_ptr = &mut 10; + /// let other_ptr = &mut 10; /// /// let value = some_ptr.compare_and_swap(ptr, other_ptr, Ordering::Relaxed); /// ``` @@ -1325,9 +1333,9 @@ impl<T> AtomicPtr<T> { /// use std::sync::atomic::{AtomicPtr, Ordering}; /// /// let ptr = &mut 5; - /// let some_ptr = AtomicPtr::new(ptr); + /// let some_ptr = AtomicPtr::new(ptr); /// - /// let other_ptr = &mut 10; + /// let other_ptr = &mut 10; /// /// let value = some_ptr.compare_exchange(ptr, other_ptr, /// Ordering::SeqCst, Ordering::Relaxed); @@ -1422,6 +1430,14 @@ impl<T> AtomicPtr<T> { /// **Note:** This method is only available on platforms that support atomic /// operations on pointers. /// + /// # Considerations + /// + /// This method is not magic; it is not provided by the hardware. + /// It is implemented in terms of [`AtomicPtr::compare_exchange_weak`], and suffers from the same drawbacks. + /// In particular, this method will not circumvent the [ABA Problem]. + /// + /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem + /// /// # Examples /// /// ```rust @@ -1554,8 +1570,8 @@ impl<T> AtomicPtr<T> { /// Offsets the pointer's address by adding `val` *bytes*, returning the /// previous pointer. /// - /// This is equivalent to using [`wrapping_add`] and [`cast`] to atomically - /// perform `ptr = ptr.cast::<u8>().wrapping_add(val).cast::<T>()`. + /// This is equivalent to using [`wrapping_byte_add`] to atomically + /// perform `ptr = ptr.wrapping_byte_add(val)`. /// /// `fetch_byte_add` takes an [`Ordering`] argument which describes the /// memory ordering of this operation. All ordering modes are possible. Note @@ -1565,8 +1581,7 @@ impl<T> AtomicPtr<T> { /// **Note**: This method is only available on platforms that support atomic /// operations on [`AtomicPtr`]. /// - /// [`wrapping_add`]: pointer::wrapping_add - /// [`cast`]: pointer::cast + /// [`wrapping_byte_add`]: pointer::wrapping_byte_add /// /// # Examples /// @@ -1584,23 +1599,15 @@ impl<T> AtomicPtr<T> { #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub fn fetch_byte_add(&self, val: usize, order: Ordering) -> *mut T { - #[cfg(not(bootstrap))] - // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_add(self.p.get(), core::ptr::invalid_mut(val), order).cast() - } - #[cfg(bootstrap)] // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_add(self.p.get().cast::<usize>(), val, order) as *mut T - } + unsafe { atomic_add(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } /// Offsets the pointer's address by subtracting `val` *bytes*, returning the /// previous pointer. /// - /// This is equivalent to using [`wrapping_sub`] and [`cast`] to atomically - /// perform `ptr = ptr.cast::<u8>().wrapping_sub(val).cast::<T>()`. + /// This is equivalent to using [`wrapping_byte_sub`] to atomically + /// perform `ptr = ptr.wrapping_byte_sub(val)`. /// /// `fetch_byte_sub` takes an [`Ordering`] argument which describes the /// memory ordering of this operation. All ordering modes are possible. Note @@ -1610,8 +1617,7 @@ impl<T> AtomicPtr<T> { /// **Note**: This method is only available on platforms that support atomic /// operations on [`AtomicPtr`]. /// - /// [`wrapping_sub`]: pointer::wrapping_sub - /// [`cast`]: pointer::cast + /// [`wrapping_byte_sub`]: pointer::wrapping_byte_sub /// /// # Examples /// @@ -1628,24 +1634,16 @@ impl<T> AtomicPtr<T> { #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub fn fetch_byte_sub(&self, val: usize, order: Ordering) -> *mut T { - #[cfg(not(bootstrap))] // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_sub(self.p.get(), core::ptr::invalid_mut(val), order).cast() - } - #[cfg(bootstrap)] - // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_sub(self.p.get().cast::<usize>(), val, order) as *mut T - } + unsafe { atomic_sub(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } /// Performs a bitwise "or" operation on the address of the current pointer, /// and the argument `val`, and stores a pointer with provenance of the /// current pointer and the resulting address. /// - /// This is equivalent equivalent to using [`map_addr`] to atomically - /// perform `ptr = ptr.map_addr(|a| a | val)`. This can be used in tagged + /// This is equivalent to using [`map_addr`] to atomically perform + /// `ptr = ptr.map_addr(|a| a | val)`. This can be used in tagged /// pointer schemes to atomically set tag bits. /// /// **Caveat**: This operation returns the previous value. To compute the @@ -1687,24 +1685,16 @@ impl<T> AtomicPtr<T> { #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub fn fetch_or(&self, val: usize, order: Ordering) -> *mut T { - #[cfg(not(bootstrap))] - // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_or(self.p.get(), core::ptr::invalid_mut(val), order).cast() - } - #[cfg(bootstrap)] // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_or(self.p.get().cast::<usize>(), val, order) as *mut T - } + unsafe { atomic_or(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } /// Performs a bitwise "and" operation on the address of the current /// pointer, and the argument `val`, and stores a pointer with provenance of /// the current pointer and the resulting address. /// - /// This is equivalent equivalent to using [`map_addr`] to atomically - /// perform `ptr = ptr.map_addr(|a| a & val)`. This can be used in tagged + /// This is equivalent to using [`map_addr`] to atomically perform + /// `ptr = ptr.map_addr(|a| a & val)`. This can be used in tagged /// pointer schemes to atomically unset tag bits. /// /// **Caveat**: This operation returns the previous value. To compute the @@ -1745,24 +1735,16 @@ impl<T> AtomicPtr<T> { #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub fn fetch_and(&self, val: usize, order: Ordering) -> *mut T { - #[cfg(not(bootstrap))] - // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_and(self.p.get(), core::ptr::invalid_mut(val), order).cast() - } - #[cfg(bootstrap)] // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_and(self.p.get().cast::<usize>(), val, order) as *mut T - } + unsafe { atomic_and(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } /// Performs a bitwise "xor" operation on the address of the current /// pointer, and the argument `val`, and stores a pointer with provenance of /// the current pointer and the resulting address. /// - /// This is equivalent equivalent to using [`map_addr`] to atomically - /// perform `ptr = ptr.map_addr(|a| a ^ val)`. This can be used in tagged + /// This is equivalent to using [`map_addr`] to atomically perform + /// `ptr = ptr.map_addr(|a| a ^ val)`. This can be used in tagged /// pointer schemes to atomically toggle tag bits. /// /// **Caveat**: This operation returns the previous value. To compute the @@ -1801,16 +1783,8 @@ impl<T> AtomicPtr<T> { #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub fn fetch_xor(&self, val: usize, order: Ordering) -> *mut T { - #[cfg(not(bootstrap))] - // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_xor(self.p.get(), core::ptr::invalid_mut(val), order).cast() - } - #[cfg(bootstrap)] // SAFETY: data races are prevented by atomic intrinsics. - unsafe { - atomic_xor(self.p.get().cast::<usize>(), val, order) as *mut T - } + unsafe { atomic_xor(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } } @@ -2552,6 +2526,16 @@ macro_rules! atomic_int { /// **Note**: This method is only available on platforms that support atomic operations on #[doc = concat!("[`", $s_int_type, "`].")] /// + /// # Considerations + /// + /// This method is not magic; it is not provided by the hardware. + /// It is implemented in terms of + #[doc = concat!("[`", stringify!($atomic_type), "::compare_exchange_weak`],")] + /// and suffers from the same drawbacks. + /// In particular, this method will not circumvent the [ABA Problem]. + /// + /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem + /// /// # Examples /// /// ```rust @@ -3073,30 +3057,22 @@ unsafe fn atomic_compare_exchange<T: Copy>( let (val, ok) = unsafe { match (success, failure) { (Relaxed, Relaxed) => intrinsics::atomic_cxchg_relaxed_relaxed(dst, old, new), - #[cfg(not(bootstrap))] (Relaxed, Acquire) => intrinsics::atomic_cxchg_relaxed_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Relaxed, SeqCst) => intrinsics::atomic_cxchg_relaxed_seqcst(dst, old, new), (Acquire, Relaxed) => intrinsics::atomic_cxchg_acquire_relaxed(dst, old, new), (Acquire, Acquire) => intrinsics::atomic_cxchg_acquire_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Acquire, SeqCst) => intrinsics::atomic_cxchg_acquire_seqcst(dst, old, new), (Release, Relaxed) => intrinsics::atomic_cxchg_release_relaxed(dst, old, new), - #[cfg(not(bootstrap))] (Release, Acquire) => intrinsics::atomic_cxchg_release_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Release, SeqCst) => intrinsics::atomic_cxchg_release_seqcst(dst, old, new), (AcqRel, Relaxed) => intrinsics::atomic_cxchg_acqrel_relaxed(dst, old, new), (AcqRel, Acquire) => intrinsics::atomic_cxchg_acqrel_acquire(dst, old, new), - #[cfg(not(bootstrap))] (AcqRel, SeqCst) => intrinsics::atomic_cxchg_acqrel_seqcst(dst, old, new), (SeqCst, Relaxed) => intrinsics::atomic_cxchg_seqcst_relaxed(dst, old, new), (SeqCst, Acquire) => intrinsics::atomic_cxchg_seqcst_acquire(dst, old, new), (SeqCst, SeqCst) => intrinsics::atomic_cxchg_seqcst_seqcst(dst, old, new), (_, AcqRel) => panic!("there is no such thing as an acquire-release failure ordering"), (_, Release) => panic!("there is no such thing as a release failure ordering"), - #[cfg(bootstrap)] - _ => panic!("a failure ordering can't be stronger than a success ordering"), } }; if ok { Ok(val) } else { Err(val) } @@ -3116,30 +3092,22 @@ unsafe fn atomic_compare_exchange_weak<T: Copy>( let (val, ok) = unsafe { match (success, failure) { (Relaxed, Relaxed) => intrinsics::atomic_cxchgweak_relaxed_relaxed(dst, old, new), - #[cfg(not(bootstrap))] (Relaxed, Acquire) => intrinsics::atomic_cxchgweak_relaxed_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Relaxed, SeqCst) => intrinsics::atomic_cxchgweak_relaxed_seqcst(dst, old, new), (Acquire, Relaxed) => intrinsics::atomic_cxchgweak_acquire_relaxed(dst, old, new), (Acquire, Acquire) => intrinsics::atomic_cxchgweak_acquire_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Acquire, SeqCst) => intrinsics::atomic_cxchgweak_acquire_seqcst(dst, old, new), (Release, Relaxed) => intrinsics::atomic_cxchgweak_release_relaxed(dst, old, new), - #[cfg(not(bootstrap))] (Release, Acquire) => intrinsics::atomic_cxchgweak_release_acquire(dst, old, new), - #[cfg(not(bootstrap))] (Release, SeqCst) => intrinsics::atomic_cxchgweak_release_seqcst(dst, old, new), (AcqRel, Relaxed) => intrinsics::atomic_cxchgweak_acqrel_relaxed(dst, old, new), (AcqRel, Acquire) => intrinsics::atomic_cxchgweak_acqrel_acquire(dst, old, new), - #[cfg(not(bootstrap))] (AcqRel, SeqCst) => intrinsics::atomic_cxchgweak_acqrel_seqcst(dst, old, new), (SeqCst, Relaxed) => intrinsics::atomic_cxchgweak_seqcst_relaxed(dst, old, new), (SeqCst, Acquire) => intrinsics::atomic_cxchgweak_seqcst_acquire(dst, old, new), (SeqCst, SeqCst) => intrinsics::atomic_cxchgweak_seqcst_seqcst(dst, old, new), (_, AcqRel) => panic!("there is no such thing as an acquire-release failure ordering"), (_, Release) => panic!("there is no such thing as a release failure ordering"), - #[cfg(bootstrap)] - _ => panic!("a failure ordering can't be stronger than a success ordering"), } }; if ok { Ok(val) } else { Err(val) } diff --git a/library/core/src/sync/exclusive.rs b/library/core/src/sync/exclusive.rs index a7519ab5a..c65c27500 100644 --- a/library/core/src/sync/exclusive.rs +++ b/library/core/src/sync/exclusive.rs @@ -100,6 +100,7 @@ impl<T: Sized> Exclusive<T> { /// Wrap a value in an `Exclusive` #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn new(t: T) -> Self { Self { inner: t } } @@ -107,6 +108,7 @@ impl<T: Sized> Exclusive<T> { /// Unwrap the value contained in the `Exclusive` #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn into_inner(self) -> T { self.inner } @@ -116,6 +118,7 @@ impl<T: ?Sized> Exclusive<T> { /// Get exclusive access to the underlying value. #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn get_mut(&mut self) -> &mut T { &mut self.inner } @@ -128,6 +131,7 @@ impl<T: ?Sized> Exclusive<T> { /// produce _pinned_ access to the underlying value. #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> { // SAFETY: `Exclusive` can only produce `&mut T` if itself is unpinned // `Pin::map_unchecked_mut` is not const, so we do this conversion manually @@ -139,6 +143,7 @@ impl<T: ?Sized> Exclusive<T> { /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn from_mut(r: &'_ mut T) -> &'_ mut Exclusive<T> { // SAFETY: repr is ≥ C, so refs have the same layout; and `Exclusive` properties are `&mut`-agnostic unsafe { &mut *(r as *mut T as *mut Exclusive<T>) } @@ -149,6 +154,7 @@ impl<T: ?Sized> Exclusive<T> { /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] #[must_use] + #[inline] pub const fn from_pin_mut(r: Pin<&'_ mut T>) -> Pin<&'_ mut Exclusive<T>> { // SAFETY: `Exclusive` can only produce `&mut T` if itself is unpinned // `Pin::map_unchecked_mut` is not const, so we do this conversion manually @@ -158,6 +164,7 @@ impl<T: ?Sized> Exclusive<T> { #[unstable(feature = "exclusive_wrapper", issue = "98407")] impl<T> From<T> for Exclusive<T> { + #[inline] fn from(t: T) -> Self { Self::new(t) } @@ -166,7 +173,7 @@ impl<T> From<T> for Exclusive<T> { #[unstable(feature = "exclusive_wrapper", issue = "98407")] impl<T: Future + ?Sized> Future for Exclusive<T> { type Output = T::Output; - + #[inline] fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { self.get_pin_mut().poll(cx) } |