From: Mark Shannon <mark@hotpy.org>
Date: Mon, 19 Jul 2021 10:10:21 +0000 (+0100)
Subject: bpo-44645: Check for interrupts on any potentially backwards edge (GH-27216)
X-Git-Tag: v3.11.0a1~633
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d09c13417890427f829e3df297beb0e27133f8f4;p=thirdparty%2FPython%2Fcpython.git

bpo-44645: Check for interrupts on any potentially backwards edge (GH-27216)
---

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index f648a8b2bc52..23fe2d3f4d32 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -1604,6 +1604,31 @@ class InterruptMainTests(unittest.TestCase):
         self.assertRaises(ValueError, _thread.interrupt_main, signal.NSIG)
         self.assertRaises(ValueError, _thread.interrupt_main, 1000000)
 
+    @threading_helper.reap_threads
+    def test_can_interrupt_tight_loops(self):
+        cont = [True]
+        started = [False]
+        interrupted = [False]
+
+        def worker(started, cont, interrupted):
+            iterations = 100_000_000
+            started[0] = True
+            while cont[0]:
+                if iterations:
+                    iterations -= 1
+                else:
+                    return
+                pass
+            interrupted[0] = True
+
+        t = threading.Thread(target=worker,args=(started, cont, interrupted))
+        t.start()
+        while not started[0]:
+            pass
+        cont[0] = False
+        t.join()
+        self.assertTrue(interrupted[0])
+
 
 class AtexitTests(unittest.TestCase):
 
diff --git a/Python/ceval.c b/Python/ceval.c
index a6eb83a4909d..90112aa3f947 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -3638,14 +3638,17 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
             if (Py_IsFalse(cond)) {
                 Py_DECREF(cond);
                 JUMPTO(oparg);
+                CHECK_EVAL_BREAKER();
                 DISPATCH();
             }
             err = PyObject_IsTrue(cond);
             Py_DECREF(cond);
             if (err > 0)
                 ;
-            else if (err == 0)
+            else if (err == 0) {
                 JUMPTO(oparg);
+                CHECK_EVAL_BREAKER();
+            }
             else
                 goto error;
             DISPATCH();
@@ -3662,12 +3665,14 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
             if (Py_IsTrue(cond)) {
                 Py_DECREF(cond);
                 JUMPTO(oparg);
+                CHECK_EVAL_BREAKER();
                 DISPATCH();
             }
             err = PyObject_IsTrue(cond);
             Py_DECREF(cond);
             if (err > 0) {
                 JUMPTO(oparg);
+                CHECK_EVAL_BREAKER();
             }
             else if (err == 0)
                 ;