https://github.com/python/cpython/commit/1eff27f2c0452b3114bcf139062c87c025842c3e
commit: 1eff27f2c0452b3114bcf139062c87c025842c3e
branch: main
author: Sam Gross <[email protected]>
committer: colesbury <[email protected]>
date: 2026-03-20T15:38:35-04:00
summary:
gh-146227: Fix wrong type in _Py_atomic_load_uint16 in pyatomic_std.h
(gh-146229)
Also fix a few related issues in the pyatomic headers:
* Fix _Py_atomic_store_uint_release in pyatomic_msc.h to use __stlr32
on ARM64 instead of a plain volatile store (which is only relaxed on
ARM64).
* Add missing _Py_atomic_store_uint_release to pyatomic_gcc.h.
* Fix pseudo-code comment for _Py_atomic_store_ptr_release in
pyatomic.h.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-03-20-13-07-33.gh-issue-146227.MqBPEo.rst
M Include/cpython/pyatomic.h
M Include/cpython/pyatomic_gcc.h
M Include/cpython/pyatomic_msc.h
M Include/cpython/pyatomic_std.h
diff --git a/Include/cpython/pyatomic.h b/Include/cpython/pyatomic.h
index ce907fd6a4c453..e85b360c986668 100644
--- a/Include/cpython/pyatomic.h
+++ b/Include/cpython/pyatomic.h
@@ -72,8 +72,8 @@
// def _Py_atomic_load_ptr_acquire(obj):
// return obj # acquire
//
-// def _Py_atomic_store_ptr_release(obj):
-// return obj # release
+// def _Py_atomic_store_ptr_release(obj, value):
+// obj = value # release
//
// def _Py_atomic_fence_seq_cst():
// # sequential consistency
@@ -532,6 +532,9 @@ _Py_atomic_store_int_release(int *obj, int value);
static inline int
_Py_atomic_load_int_acquire(const int *obj);
+static inline void
+_Py_atomic_store_uint_release(unsigned int *obj, unsigned int value);
+
static inline void
_Py_atomic_store_uint32_release(uint32_t *obj, uint32_t value);
diff --git a/Include/cpython/pyatomic_gcc.h b/Include/cpython/pyatomic_gcc.h
index c045213c898a03..253b35082aafcd 100644
--- a/Include/cpython/pyatomic_gcc.h
+++ b/Include/cpython/pyatomic_gcc.h
@@ -580,6 +580,10 @@ static inline void
_Py_atomic_store_ssize_release(Py_ssize_t *obj, Py_ssize_t value)
{ __atomic_store_n(obj, value, __ATOMIC_RELEASE); }
+static inline void
+_Py_atomic_store_uint_release(unsigned int *obj, unsigned int value)
+{ __atomic_store_n(obj, value, __ATOMIC_RELEASE); }
+
static inline int
_Py_atomic_load_int_acquire(const int *obj)
{ return __atomic_load_n(obj, __ATOMIC_ACQUIRE); }
diff --git a/Include/cpython/pyatomic_msc.h b/Include/cpython/pyatomic_msc.h
index 8b9dd3eb0f8e16..3b3c5f7017e957 100644
--- a/Include/cpython/pyatomic_msc.h
+++ b/Include/cpython/pyatomic_msc.h
@@ -971,12 +971,6 @@ _Py_atomic_store_ushort_relaxed(unsigned short *obj,
unsigned short value)
*(volatile unsigned short *)obj = value;
}
-static inline void
-_Py_atomic_store_uint_release(unsigned int *obj, unsigned int value)
-{
- *(volatile unsigned int *)obj = value;
-}
-
static inline void
_Py_atomic_store_long_relaxed(long *obj, long value)
{
@@ -1079,6 +1073,19 @@ _Py_atomic_store_int8_release(int8_t *obj, int8_t value)
#endif
}
+static inline void
+_Py_atomic_store_uint_release(unsigned int *obj, unsigned int value)
+{
+#if defined(_M_X64) || defined(_M_IX86)
+ *(volatile unsigned int *)obj = value;
+#elif defined(_M_ARM64)
+ _Py_atomic_ASSERT_ARG_TYPE(unsigned __int32);
+ __stlr32((unsigned __int32 volatile *)obj, (unsigned __int32)value);
+#else
+# error "no implementation of _Py_atomic_store_uint_release"
+#endif
+}
+
static inline void
_Py_atomic_store_ssize_release(Py_ssize_t *obj, Py_ssize_t value)
{
diff --git a/Include/cpython/pyatomic_std.h b/Include/cpython/pyatomic_std.h
index cfc8dbefc63d09..faef303da70314 100644
--- a/Include/cpython/pyatomic_std.h
+++ b/Include/cpython/pyatomic_std.h
@@ -459,7 +459,7 @@ static inline uint16_t
_Py_atomic_load_uint16(const uint16_t *obj)
{
_Py_USING_STD;
- return atomic_load((const _Atomic(uint32_t)*)obj);
+ return atomic_load((const _Atomic(uint16_t)*)obj);
}
static inline uint32_t
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-20-13-07-33.gh-issue-146227.MqBPEo.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-20-13-07-33.gh-issue-146227.MqBPEo.rst
new file mode 100644
index 00000000000000..11e19eb28313d6
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-20-13-07-33.gh-issue-146227.MqBPEo.rst
@@ -0,0 +1,3 @@
+Fix wrong type in ``_Py_atomic_load_uint16`` in the C11 atomics backend
+(``pyatomic_std.h``), which used a 32-bit atomic load instead of 16-bit.
+Found by Mohammed Zuhaib.
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