gh-155363: Fix QSBR slot leak on thread state creation failure - #155365
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In the free-threaded build, new_threadstate() reserves a QSBR thread-state slot before it can still fail for other reasons, but the failure paths only called free_threadstate(), which does not know about the reservation.
nascheme
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August 7, 2026 21:29
nascheme
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ericsnowcurrently
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August 7, 2026 21:29
By moving the call before the _Py_qsbr_reserve, we don't need the _Py_qsbr_unreserve helper and code is a bit simpler.
…sbr-reserve-leak
kumaraditya303
approved these changes
Aug 11, 2026
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Thanks @nascheme for the PR 🌮🎉.. I'm working now to backport this PR to: 3.15. |
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GH-155579 is a backport of this pull request to the 3.15 branch. |
mbeijen
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Aug 14, 2026
…ythongh-155365) In the free-threaded build, new_threadstate() reserves a QSBR thread-state slot before it can still fail for other reasons, but the failure paths only called free_threadstate(), which does not know about the reservation. Restructure code so failure path doesn't leak.
hugovk
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Aug 22, 2026
…gh-155365) (#155579) Co-authored-by: Neil Schemenauer <nas-github@arctrix.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org>
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In the free-threaded build,
new_threadstate()reserves a QSBR thread-state slot before it can still fail for other reasons, but the failure paths only calledfree_threadstate(), which does not know about the reservation.Add
_Py_qsbr_unreserve()which returns the unregistered entry to the freelist.