gh-137185: Fix `_Py_DumpStack()` async signal safety (gh-137187) · python/cpython@11a8652 · GitHub
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gh-137185: Fix _Py_DumpStack() async signal safety (gh-137187)
Call backtrace() once when installing the signal handler to ensure that libgcc is dynamically loaded outside the signal handler. This fixes a "signal-unsafe call inside of a signal" TSan error from test_faulthandler.test_enable_fd.
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‎Include/internal/pycore_traceback.h‎

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‎Misc/NEWS.d/next/Library/2025-07-28-20-48-32.gh-issue-137185.fgI7-B.rst‎

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Fix a potential async-signal-safety issue in :mod:`faulthandler` when
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printing C stack traces.

‎Modules/faulthandler.c‎

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}
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#endif
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// gh-137185: Initialize C stack trace dumping outside of the signal
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// handler. Specifically, we call backtrace() to ensure that libgcc is
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// dynamically loaded outside of the signal handler.
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_Py_InitDumpStack();
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for (size_t i=0; i < faulthandler_nsignals; i++) {
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fault_handler_t *handler;
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int err;

‎Python/traceback.c‎

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