tests/thread_race: add test for race conditions

tests/thread_race/Makefile

@@ -0,0 +1,10 @@
+include ../Makefile.tests_common
+
+DISABLE_MODULE += auto_init
+
+TEST_ON_CI_WHITELIST += all
+
+include $(RIOTBASE)/Makefile.include
+
+test:
+	tests/01-run.py

tests/thread_race/main.c

@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2018 Matthew Blue <matthew.blue.neuro@gmail.com>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     test
+ * @{
+ *
+ * @file
+ * @brief       Test for race conditions in context switching
+ *
+ * May have false negatives.
+ *
+ * @author      Matthew Blue <matthew.blue.neuro@gmail.com>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+
+#include "irq.h"
+#include "sched.h"
+#include "thread.h"
+
+char iqr_check_stack[THREAD_STACKSIZE_DEFAULT];
+
+static volatile uint8_t irq_occurred;
+
+static void *_thread_irq_check(void *arg)
+{
+    (void)arg;
+
+    while (1) {
+        irq_occurred = 1;
+
+        thread_sleep();
+    }
+
+    return NULL;
+}
+
+/* Mostly copied from thread_wakeup() */
+static void _thread_wake_wo_yield(kernel_pid_t pid)
+{
+    unsigned old_state = irq_disable();
+
+    thread_t *other_thread = (thread_t *) thread_get(pid);
+
+    sched_set_status(other_thread, STATUS_RUNNING);
+
+    irq_restore(old_state);
+}
+
+static void _spin(void)
+{
+    /* Volatile so it is not messed with by optimizations */
+    volatile uint8_t i;
+
+    for (i = 0; i < 255; i++) ;
+}
+
+int main(void)
+{
+    puts("Context swap race condition test application");
+
+    kernel_pid_t pid;
+
+    puts("Starting IRQ check thread");
+    pid = thread_create(iqr_check_stack, sizeof(iqr_check_stack),
+                        THREAD_PRIORITY_MAIN - 1,
+                        THREAD_CREATE_SLEEPING,
+                        _thread_irq_check, NULL, "irqchk");
+
+    printf("Checking for working context swap (to detect false positives)... ");
+    irq_occurred = 0;
+    _thread_wake_wo_yield(pid);
+
+    thread_yield_higher();
+
+    /* Delay so we are not testing for race conditions also */
+    _spin();
+
+    if (irq_occurred == 1) {
+        puts("[Success]");
+    }
+    else {
+        puts("[Failed]");
+        return -1;
+    }
+
+    printf("Checking for reset of swaps (to detect false positives)... ");
+    irq_occurred = 0;
+    _thread_wake_wo_yield(pid);
+
+    thread_yield_higher();
+
+    /* Delay so we are not testing for race conditions also */
+    _spin();
+
+    if (irq_occurred == 1) {
+        puts("[Success]");
+    }
+    else {
+        puts("[Failed]");
+        return -1;
+    }
+
+    /* Volatile so it is not messed with by optimizations */
+    volatile uint8_t race_test;
+
+    printf("Checking for context swap race condition... ");
+    irq_occurred = 0;
+    _thread_wake_wo_yield(pid);
+
+    thread_yield_higher();
+
+    /* Race instruction */
+    race_test = irq_occurred;
+
+    if (race_test == 1) {
+        puts("[Success]");
+    }
+    else {
+        puts("[Failed]");
+        return -1;
+    }
+
+    return 0;
+}

tests/thread_race/tests/01-run.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2018 Matthew Blue <matthew.blue.neuro@gmail.com>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import os
+import sys
+
+
+def testfunc(child):
+    child.expect_exact("Context swap race condition test application")
+    child.expect_exact("Starting IRQ check thread")
+    child.expect_exact(
+        "Checking for working context swap (to detect false positives)... [Success]")
+    child.expect_exact(
+        "Checking for reset of swaps (to detect false positives)... [Success]")
+    child.expect_exact("Checking for context swap race condition... [Success]")
+
+
+if __name__ == "__main__":
+    sys.path.append(os.path.join(os.environ['RIOTBASE'], 'dist/tools/testrunner'))
+    from testrunner import run
+    sys.exit(run(testfunc))