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Rollup merge ofrust-lang#127813 - ChrisDenton:win-futex, r=joboet

Prevent double reference in generic futexIn the Windows futex implementation we were a little lax at allowing references to references (i.e. `&&`) which can lead to deadlocks due to reading the wrong memory address. This uses a trait to tighten the constraints and ensure this doesn't happen.r? libs

2 parentsaeae332 +e0ea701 commita2cf636Copy full SHA for a2cf636

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2 files changed

-5

lines changed

std/src/sys
- pal/windows
  - futex.rs
- sync/once
  - futex.rs

2 files changed

-5

lines changed

`‎std/src/sys/pal/windows/futex.rs‎`

Lines changed: 7 additions & 4 deletions

Original file line number	Diff line number	Diff line change
`@@ -15,6 +15,7 @@ pub type SmallAtomic = AtomicU8;`
`15`	`15`	`/// Must be the underlying type of SmallAtomic`
`16`	`16`	`pubtypeSmallPrimitive =u8;`
`17`	`17`
	`18`	`+pubunsafetraitFutex{}`
`18`	`19`	`pubunsafetraitWaitable{`
`19`	`20`	`typeAtomic;`
`20`	`21`	`}`
`@@ -24,6 +25,7 @@ macro_rules! unsafe_waitable_int {`
`24`	`25`	`unsafeimplWaitablefor $int{`
`25`	`26`	`typeAtomic = $atomic;`
`26`	`27`	`}`
	`28`	`+unsafeimplFutexfor $atomic{}`
`27`	`29`	`)*`
`28`	`30`	`};`
`29`	`31`	`}`
`@@ -46,6 +48,7 @@ unsafe impl<T> Waitable for *const T {`
`46`	`48`	`unsafeimpl<T>Waitablefor*mutT{`
`47`	`49`	`typeAtomic =AtomicPtr<T>;`
`48`	`50`	`}`
	`51`	`+unsafeimpl<T>FutexforAtomicPtr<T>{}`
`49`	`52`
`50`	`53`	`pubfnwait_on_address<W:Waitable>(`
`51`	`54`	`address:&W::Atomic,`
`@@ -61,14 +64,14 @@ pub fn wait_on_address<W: Waitable>(`
`61`	`64`	`}`
`62`	`65`	`}`
`63`	`66`
`64`		`-pubfnwake_by_address_single<T>(address:&T){`
	`67`	`+pubfnwake_by_address_single<T:Futex>(address:&T){`
`65`	`68`	`unsafe{`
`66`	`69`	`let addr = ptr::from_ref(address).cast::<c_void>();`
`67`	`70`	`c::WakeByAddressSingle(addr);`
`68`	`71`	`}`
`69`	`72`	`}`
`70`	`73`
`71`		`-pubfnwake_by_address_all<T>(address:&T){`
	`74`	`+pubfnwake_by_address_all<T:Futex>(address:&T){`
`72`	`75`	`unsafe{`
`73`	`76`	`let addr = ptr::from_ref(address).cast::<c_void>();`
`74`	`77`	`c::WakeByAddressAll(addr);`
`@@ -80,11 +83,11 @@ pub fn futex_wait<W: Waitable>(futex: &W::Atomic, expected: W, timeout: Option<D`
`80`	`83`	`wait_on_address(futex, expected, timeout) \|\| api::get_last_error() !=WinError::TIMEOUT`
`81`	`84`	`}`
`82`	`85`
`83`		`-pubfnfutex_wake<T>(futex:&T) ->bool{`
	`86`	`+pubfnfutex_wake<T:Futex>(futex:&T) ->bool{`
`84`	`87`	`wake_by_address_single(futex);`
`85`	`88`	`false`
`86`	`89`	`}`
`87`	`90`
`88`		`-pubfnfutex_wake_all<T>(futex:&T){`
	`91`	`+pubfnfutex_wake_all<T:Futex>(futex:&T){`
`89`	`92`	`wake_by_address_all(futex)`
`90`	`93`	`}`

`‎std/src/sys/sync/once/futex.rs‎`

Lines changed: 1 addition & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -57,7 +57,7 @@ impl<'a> Drop for CompletionGuard<'a> {`
`57`	`57`	// up on the Once. `futex_wake_all` does its own synchronization, hence
`58`	`58`	// we do not need `AcqRel`.
`59`	`59`	`ifself.state.swap(self.set_state_on_drop_to,Release) ==QUEUED{`
`60`		`-futex_wake_all(&self.state);`
	`60`	`+futex_wake_all(self.state);`
`61`	`61`	`}`
`62`	`62`	`}`
`63`	`63`	`}`

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`‎std/src/sys/pal/windows/futex.rs‎`

`‎std/src/sys/sync/once/futex.rs‎`

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