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GeezerVison is showing github.com — gh-117657: Fix data race in `_Py_IsImmortal` by mpage · Pull Request #118261 · python/cpython

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@mpage

@mpage mpage commented Apr 24, 2024 •
edited by bedevere-app Bot
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The load of ob_ref_local:

cpython/Include/object.h

Line 352 in 4b10e20

return (op->ob_ref_local == _Py_IMMORTAL_REFCNT_LOCAL);

races with stores (example):

cpython/Include/object.h

Line 883 in 4b10e20

_Py_atomic_store_uint32_relaxed(&op->ob_ref_local, local);

Using a relaxed load is sufficient; stores to the field are relaxed.

  • Issue: Make TSAN tests pass with the GIL disabled in free-threaded builds #117657

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@mpage
Fix data race in _Py_IsImmortal
18d376b 
The load of `ob_ref_local`:

https://github.com/python/cpython/blob/4b10e209c76f9f36f8ae2e4d713b3a01591c1856/Include/object.h#L352

races with ([example](https://gist.github.com/mpage/7e2028b3ca811deb350f705bc3c737ca)) stores:

https://github.com/python/cpython/blob/4b10e209c76f9f36f8ae2e4d713b3a01591c1856/Include/object.h#L883

Using a relaxed load is sufficient; stores to the field are relaxed.
@mpage mpage added skip news topic-free-threading labels Apr 24, 2024
@mpage
mpage requested review from DinoV and colesbury April 24, 2024 23:52
@bedevere-app bedevere-app Bot mentioned this pull request Apr 24, 2024
Make TSAN tests pass with the GIL disabled in free-threaded builds #117657
Closed
@mpage
mpage marked this pull request as ready for review April 25, 2024 03:12
@bedevere-app bedevere-app Bot added the awaiting review label Apr 25, 2024
colesbury
colesbury approved these changes Apr 25, 2024
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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting review labels Apr 25, 2024
@colesbury
colesbury merged commit f14e9f9 into python:main Apr 25, 2024
@bedevere-app bedevere-app Bot removed the awaiting merge label Apr 25, 2024
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@colesbury colesbury colesbury approved these changes
@DinoV DinoV Awaiting requested review from DinoV

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@mpage @colesbury
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