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avoid mutable references in critical_section_mutex implementations #6050

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Merged
ngoldbaum merged 1 commit into from
May 16, 2026
+4 −4
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avoid mutable references in critical_section_mutex implementations #6050

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8 changes: 4 additions & 4 deletions src/sync/critical_section.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -198,7 +198,7 @@ where
#[cfg(Py_GIL_DISABLED)]
{
let mut guard = CSGuard(unsafe { core::mem::zeroed() });
unsafe { crate::ffi::PyCriticalSection_BeginMutex(&mut guard.0, &mut *mutex.mutex.get()) };
unsafe { crate::ffi::PyCriticalSection_BeginMutex(&raw mut guard.0, mutex.mutex.get()) };
f(EnteredCriticalSection(&mutex.data))
}
#[cfg(not(Py_GIL_DISABLED))]
Expand Down Expand Up @@ -243,9 +243,9 @@ where
let mut guard = CS2Guard(unsafe { core::mem::zeroed() });
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@davidhewitt davidhewitt May 16, 2026

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While we're here, I think we might be able to replace these core::mem::zeroed() with MaybeUninit of some form, to avoid needing to zero-intialize the structures at each critical section entry.

Looks like the C headers don't zero-initialize:

https://github.com/python/cpython/blob/a7ed0c9e1dee1397e80e2e0d90d110155da2bc30/Include/critical_section.h#L74-L90

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@davidhewitt davidhewitt May 16, 2026

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(Possibly better to defer this to a separate PR given correctness / performance implications are not related to the exact diff here.)

unsafe {
crate::ffi::PyCriticalSection2_BeginMutex(
&mut guard.0,
&mut *m1.mutex.get(),
&mut *m2.mutex.get(),
&raw mut guard.0,
m1.mutex.get(),
m2.mutex.get(),
)
};
f(
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