From 64d98f8ee037282c35007b64c2649055c56af1db Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:19:03 +0200 Subject: Merging upstream version 1.68.2+dfsg1. Signed-off-by: Daniel Baumann --- library/core/src/sync/atomic.rs | 40 ++++++++++++++++++++++++++++++++++++-- library/core/src/sync/exclusive.rs | 4 ++-- 2 files changed, 40 insertions(+), 4 deletions(-) (limited to 'library/core/src/sync') diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index edc68d6fa..14367eb09 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -1786,6 +1786,42 @@ impl AtomicPtr { // SAFETY: data races are prevented by atomic intrinsics. unsafe { atomic_xor(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } + + /// Returns a mutable pointer to the underlying pointer. + /// + /// Doing non-atomic reads and writes on the resulting integer can be a data race. + /// This method is mostly useful for FFI, where the function signature may use + /// `*mut *mut T` instead of `&AtomicPtr`. + /// + /// Returning an `*mut` pointer from a shared reference to this atomic is safe because the + /// atomic types work with interior mutability. All modifications of an atomic change the value + /// through a shared reference, and can do so safely as long as they use atomic operations. Any + /// use of the returned raw pointer requires an `unsafe` block and still has to uphold the same + /// restriction: operations on it must be atomic. + /// + /// # Examples + /// + /// ```ignore (extern-declaration) + /// #![feature(atomic_mut_ptr)] + //// use std::sync::atomic::AtomicPtr; + /// + /// extern "C" { + /// fn my_atomic_op(arg: *mut *mut u32); + /// } + /// + /// let mut value = 17; + /// let atomic = AtomicPtr::new(&mut value); + /// + /// // SAFETY: Safe as long as `my_atomic_op` is atomic. + /// unsafe { + /// my_atomic_op(atomic.as_mut_ptr()); + /// } + /// ``` + #[inline] + #[unstable(feature = "atomic_mut_ptr", reason = "recently added", issue = "66893")] + pub fn as_mut_ptr(&self) -> *mut *mut T { + self.p.get() + } } #[cfg(target_has_atomic_load_store = "8")] @@ -2678,9 +2714,9 @@ macro_rules! atomic_int { #[doc = concat!(" fn my_atomic_op(arg: *mut ", stringify!($int_type), ");")] /// } /// - #[doc = concat!("let mut atomic = ", stringify!($atomic_type), "::new(1);")] + #[doc = concat!("let atomic = ", stringify!($atomic_type), "::new(1);")] /// - // SAFETY: Safe as long as `my_atomic_op` is atomic. + /// // SAFETY: Safe as long as `my_atomic_op` is atomic. /// unsafe { /// my_atomic_op(atomic.as_mut_ptr()); /// } diff --git a/library/core/src/sync/exclusive.rs b/library/core/src/sync/exclusive.rs index c65c27500..301ad41c9 100644 --- a/library/core/src/sync/exclusive.rs +++ b/library/core/src/sync/exclusive.rs @@ -138,7 +138,7 @@ impl Exclusive { unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().inner) } } - /// Build a _mutable_ references to an `Exclusive` from + /// Build a _mutable_ reference to an `Exclusive` from /// a _mutable_ reference to a `T`. This allows you to skip /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] @@ -149,7 +149,7 @@ impl Exclusive { unsafe { &mut *(r as *mut T as *mut Exclusive) } } - /// Build a _pinned mutable_ references to an `Exclusive` from + /// Build a _pinned mutable_ reference to an `Exclusive` from /// a _pinned mutable_ reference to a `T`. This allows you to skip /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] -- cgit v1.2.3