From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Sat, 1 Jun 2024 14:51:55 +0000 (+0200)
Subject: [3.13] gh-117657: Fix TSAN race in QSBR assertion (GH-119887) (#119904)
X-Git-Tag: v3.13.0b2~54
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=48054d2306fed2a2a53d8e5dba9c1aa7ef138ed5;p=thirdparty%2FPython%2Fcpython.git

[3.13] gh-117657: Fix TSAN race in QSBR assertion (GH-119887) (#119904)

Due to a limitation in TSAN, all reads from `PyThreadState.state` must be
atomic to avoid reported races.
(cherry picked from commit 90ec19fd33e2452902b9788d4821f1fbf6542304)

Co-authored-by: Sam Gross <colesbury@gmail.com>
---

diff --git a/Python/qsbr.c b/Python/qsbr.c
index 9cbce9044e29..a7321154a62f 100644
--- a/Python/qsbr.c
+++ b/Python/qsbr.c
@@ -160,7 +160,8 @@ qsbr_poll_scan(struct _qsbr_shared *shared)
 bool
 _Py_qsbr_poll(struct _qsbr_thread_state *qsbr, uint64_t goal)
 {
-    assert(_PyThreadState_GET()->state == _Py_THREAD_ATTACHED);
+    assert(_Py_atomic_load_int_relaxed(&_PyThreadState_GET()->state) == _Py_THREAD_ATTACHED);
+
     if (_Py_qbsr_goal_reached(qsbr, goal)) {
         return true;
     }
diff --git a/Tools/tsan/suppressions_free_threading.txt b/Tools/tsan/suppressions_free_threading.txt
index 27568c34e168..dbb0aacb7ed9 100644
--- a/Tools/tsan/suppressions_free_threading.txt
+++ b/Tools/tsan/suppressions_free_threading.txt
@@ -76,8 +76,6 @@ race_top:_PyFrame_GetCode
 race_top:_PyFrame_Initialize
 race_top:PyInterpreterState_ThreadHead
 race_top:_PyObject_TryGetInstanceAttribute
-race_top:_Py_qsbr_unregister
-race_top:_Py_qsbr_poll
 race_top:PyThreadState_Next
 race_top:Py_TYPE
 race_top:PyUnstable_InterpreterFrame_GetLine