From 5ff7b404d5e72280934fd237d9065841c13d7c10 Mon Sep 17 00:00:00 2001 From: Jubilee Young Date: Sun, 14 Jul 2024 17:59:37 -0700 Subject: [PATCH] std: Unsafe-wrap std::sync --- std/src/sync/mod.rs | 1 - std/src/sync/mpmc/array.rs | 22 ++++++++++++-------- std/src/sync/mpmc/counter.rs | 4 ++-- std/src/sync/mpmc/list.rs | 38 +++++++++++++++++++--------------- std/src/sync/mpmc/zero.rs | 20 +++++++++++------- std/src/sync/once_lock.rs | 4 ++-- std/src/sync/reentrant_lock.rs | 4 +++- std/src/sync/rwlock.rs | 2 +- 8 files changed, 54 insertions(+), 41 deletions(-) diff --git a/std/src/sync/mod.rs b/std/src/sync/mod.rs index 5cabdc3a9c7ec..9a38c42f43a02 100644 --- a/std/src/sync/mod.rs +++ b/std/src/sync/mod.rs @@ -157,7 +157,6 @@ //! [`RwLock`]: crate::sync::RwLock #![stable(feature = "rust1", since = "1.0.0")] -#![allow(unsafe_op_in_unsafe_fn)] #[stable(feature = "rust1", since = "1.0.0")] pub use alloc_crate::sync::{Arc, Weak}; diff --git a/std/src/sync/mpmc/array.rs b/std/src/sync/mpmc/array.rs index 492e21d9bdb63..185319add745f 100644 --- a/std/src/sync/mpmc/array.rs +++ b/std/src/sync/mpmc/array.rs @@ -200,11 +200,12 @@ impl Channel { return Err(msg); } - let slot: &Slot = &*(token.array.slot as *const Slot); - // Write the message into the slot and update the stamp. - slot.msg.get().write(MaybeUninit::new(msg)); - slot.stamp.store(token.array.stamp, Ordering::Release); + unsafe { + let slot: &Slot = &*(token.array.slot as *const Slot); + slot.msg.get().write(MaybeUninit::new(msg)); + slot.stamp.store(token.array.stamp, Ordering::Release); + } // Wake a sleeping receiver. self.receivers.notify(); @@ -291,11 +292,14 @@ impl Channel { return Err(()); } - let slot: &Slot = &*(token.array.slot as *const Slot); - // Read the message from the slot and update the stamp. - let msg = slot.msg.get().read().assume_init(); - slot.stamp.store(token.array.stamp, Ordering::Release); + let msg = unsafe { + let slot: &Slot = &*(token.array.slot as *const Slot); + + let msg = slot.msg.get().read().assume_init(); + slot.stamp.store(token.array.stamp, Ordering::Release); + msg + }; // Wake a sleeping sender. self.senders.notify(); @@ -471,7 +475,7 @@ impl Channel { false }; - self.discard_all_messages(tail); + unsafe { self.discard_all_messages(tail) }; disconnected } diff --git a/std/src/sync/mpmc/counter.rs b/std/src/sync/mpmc/counter.rs index a5a6bdc67f13f..3478cf41dc9d2 100644 --- a/std/src/sync/mpmc/counter.rs +++ b/std/src/sync/mpmc/counter.rs @@ -63,7 +63,7 @@ impl Sender { disconnect(&self.counter().chan); if self.counter().destroy.swap(true, Ordering::AcqRel) { - drop(Box::from_raw(self.counter)); + drop(unsafe { Box::from_raw(self.counter) }); } } } @@ -116,7 +116,7 @@ impl Receiver { disconnect(&self.counter().chan); if self.counter().destroy.swap(true, Ordering::AcqRel) { - drop(Box::from_raw(self.counter)); + drop(unsafe { Box::from_raw(self.counter) }); } } } diff --git a/std/src/sync/mpmc/list.rs b/std/src/sync/mpmc/list.rs index 9e7148c716cda..edac7a0cb1835 100644 --- a/std/src/sync/mpmc/list.rs +++ b/std/src/sync/mpmc/list.rs @@ -91,7 +91,7 @@ impl Block { // It is not necessary to set the `DESTROY` bit in the last slot because that slot has // begun destruction of the block. for i in start..BLOCK_CAP - 1 { - let slot = (*this).slots.get_unchecked(i); + let slot = unsafe { (*this).slots.get_unchecked(i) }; // Mark the `DESTROY` bit if a thread is still using the slot. if slot.state.load(Ordering::Acquire) & READ == 0 @@ -103,7 +103,7 @@ impl Block { } // No thread is using the block, now it is safe to destroy it. - drop(Box::from_raw(this)); + drop(unsafe { Box::from_raw(this) }); } } @@ -265,9 +265,11 @@ impl Channel { // Write the message into the slot. let block = token.list.block as *mut Block; let offset = token.list.offset; - let slot = (*block).slots.get_unchecked(offset); - slot.msg.get().write(MaybeUninit::new(msg)); - slot.state.fetch_or(WRITE, Ordering::Release); + unsafe { + let slot = (*block).slots.get_unchecked(offset); + slot.msg.get().write(MaybeUninit::new(msg)); + slot.state.fetch_or(WRITE, Ordering::Release); + } // Wake a sleeping receiver. self.receivers.notify(); @@ -369,19 +371,21 @@ impl Channel { // Read the message. let block = token.list.block as *mut Block; let offset = token.list.offset; - let slot = (*block).slots.get_unchecked(offset); - slot.wait_write(); - let msg = slot.msg.get().read().assume_init(); - - // Destroy the block if we've reached the end, or if another thread wanted to destroy but - // couldn't because we were busy reading from the slot. - if offset + 1 == BLOCK_CAP { - Block::destroy(block, 0); - } else if slot.state.fetch_or(READ, Ordering::AcqRel) & DESTROY != 0 { - Block::destroy(block, offset + 1); - } + unsafe { + let slot = (*block).slots.get_unchecked(offset); + slot.wait_write(); + let msg = slot.msg.get().read().assume_init(); + + // Destroy the block if we've reached the end, or if another thread wanted to destroy but + // couldn't because we were busy reading from the slot. + if offset + 1 == BLOCK_CAP { + Block::destroy(block, 0); + } else if slot.state.fetch_or(READ, Ordering::AcqRel) & DESTROY != 0 { + Block::destroy(block, offset + 1); + } - Ok(msg) + Ok(msg) + } } /// Attempts to send a message into the channel. diff --git a/std/src/sync/mpmc/zero.rs b/std/src/sync/mpmc/zero.rs index 1b82713edc748..6d1c9d64e7a7a 100644 --- a/std/src/sync/mpmc/zero.rs +++ b/std/src/sync/mpmc/zero.rs @@ -103,9 +103,11 @@ impl Channel { return Err(msg); } - let packet = &*(token.zero.0 as *const Packet); - packet.msg.get().write(Some(msg)); - packet.ready.store(true, Ordering::Release); + unsafe { + let packet = &*(token.zero.0 as *const Packet); + packet.msg.get().write(Some(msg)); + packet.ready.store(true, Ordering::Release); + } Ok(()) } @@ -116,22 +118,24 @@ impl Channel { return Err(()); } - let packet = &*(token.zero.0 as *const Packet); + let packet = unsafe { &*(token.zero.0 as *const Packet) }; if packet.on_stack { // The message has been in the packet from the beginning, so there is no need to wait // for it. However, after reading the message, we need to set `ready` to `true` in // order to signal that the packet can be destroyed. - let msg = packet.msg.get().replace(None).unwrap(); + let msg = unsafe { packet.msg.get().replace(None) }.unwrap(); packet.ready.store(true, Ordering::Release); Ok(msg) } else { // Wait until the message becomes available, then read it and destroy the // heap-allocated packet. packet.wait_ready(); - let msg = packet.msg.get().replace(None).unwrap(); - drop(Box::from_raw(token.zero.0 as *mut Packet)); - Ok(msg) + unsafe { + let msg = packet.msg.get().replace(None).unwrap(); + drop(Box::from_raw(token.zero.0 as *mut Packet)); + Ok(msg) + } } } diff --git a/std/src/sync/once_lock.rs b/std/src/sync/once_lock.rs index fe243550606f3..94955beaf37b7 100644 --- a/std/src/sync/once_lock.rs +++ b/std/src/sync/once_lock.rs @@ -502,7 +502,7 @@ impl OnceLock { #[inline] unsafe fn get_unchecked(&self) -> &T { debug_assert!(self.is_initialized()); - (&*self.value.get()).assume_init_ref() + unsafe { (&*self.value.get()).assume_init_ref() } } /// # Safety @@ -511,7 +511,7 @@ impl OnceLock { #[inline] unsafe fn get_unchecked_mut(&mut self) -> &mut T { debug_assert!(self.is_initialized()); - (&mut *self.value.get()).assume_init_mut() + unsafe { (&mut *self.value.get()).assume_init_mut() } } } diff --git a/std/src/sync/reentrant_lock.rs b/std/src/sync/reentrant_lock.rs index f7fe8eb1c7fd5..042c439394e06 100644 --- a/std/src/sync/reentrant_lock.rs +++ b/std/src/sync/reentrant_lock.rs @@ -244,7 +244,9 @@ impl ReentrantLock { } unsafe fn increment_lock_count(&self) -> Option<()> { - *self.lock_count.get() = (*self.lock_count.get()).checked_add(1)?; + unsafe { + *self.lock_count.get() = (*self.lock_count.get()).checked_add(1)?; + } Some(()) } } diff --git a/std/src/sync/rwlock.rs b/std/src/sync/rwlock.rs index e0a8a7603d71a..a4ec52a4abe63 100644 --- a/std/src/sync/rwlock.rs +++ b/std/src/sync/rwlock.rs @@ -578,7 +578,7 @@ impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> { // successfully called from the same thread before instantiating this object. unsafe fn new(lock: &'rwlock RwLock) -> LockResult> { poison::map_result(lock.poison.borrow(), |()| RwLockReadGuard { - data: NonNull::new_unchecked(lock.data.get()), + data: unsafe { NonNull::new_unchecked(lock.data.get()) }, inner_lock: &lock.inner, }) }