From: Sam Gross <colesbury@gmail.com>
Date: Fri, 19 Dec 2025 22:33:49 +0000 (-0500)
Subject: gh-120321: Fix TSan reported race in gen_clear_frame (gh-142995)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ea3c1a04747978361b497798428423cbb6a7146;p=thirdparty%2FPython%2Fcpython.git

gh-120321: Fix TSan reported race in gen_clear_frame (gh-142995)

TSan treats compare-exchanges that fail as if they are writes
so there is a false positive with the read of gi_frame_state in
gen_close.
---

diff --git a/Objects/genobject.c b/Objects/genobject.c
index 508d215a0cfe..1e59d89f5ce8 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -153,7 +153,7 @@ _PyGen_Finalize(PyObject *self)
 static void
 gen_clear_frame(PyGenObject *gen)
 {
-    assert(gen->gi_frame_state == FRAME_CLEARED);
+    assert(FT_ATOMIC_LOAD_INT8_RELAXED(gen->gi_frame_state) == FRAME_CLEARED);
     _PyInterpreterFrame *frame = &gen->gi_iframe;
     frame->previous = NULL;
     _PyFrame_ClearExceptCode(frame);