From 6e0b327690c7dd2e4e9091f81f8ad43ad5eb1631 Mon Sep 17 00:00:00 2001 From: mpage Date: Mon, 15 Apr 2024 09:17:33 -0700 Subject: [PATCH] gh-117657: Quiet TSAN warning about a data race between `start_the_world()` and `tstate_try_attach()` (#117828) TSAN erroneously reports a data race between the `_Py_atomic_compare_exchange_int` on `tstate->state` in `tstate_try_attach()` and the non-atomic load of `tstate->state` in `start_the_world`. The `_Py_atomic_compare_exchange_int` fails, but TSAN erroneously treats it as a store. --- Python/pystate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Python/pystate.c b/Python/pystate.c index acec905484c..50454020b8f 100644 --- a/Python/pystate.c +++ b/Python/pystate.c @@ -2248,7 +2248,8 @@ start_the_world(struct _stoptheworld_state *stw) PyThreadState *t; _Py_FOR_EACH_THREAD(stw, i, t) { if (t != stw->requester) { - assert(t->state == _Py_THREAD_SUSPENDED); + assert(_Py_atomic_load_int_relaxed(&t->state) == + _Py_THREAD_SUSPENDED); _Py_atomic_store_int(&t->state, _Py_THREAD_DETACHED); _PyParkingLot_UnparkAll(&t->state); }