tests: Add test for MetaIRQ preemption of cooperative thread

Test that meta-IRQ returns to the cooperative thread it interrupted,
and not to whichever thread is highest priority at that point.

Signed-off-by: Wolfgang Puffitsch <[email protected]>

Author: wopu-ot

tests/kernel/sched/metairq/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)
+project(preempt)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

tests/kernel/sched/metairq/prj.conf

@@ -0,0 +1,3 @@
+CONFIG_ZTEST=y
+CONFIG_MP_NUM_CPUS=1
+CONFIG_NUM_METAIRQ_PRIORITIES=1

tests/kernel/sched/metairq/src/main.c

@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2019 Demant
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <zephyr.h>
+#include <ztest.h>
+#include <kernel.h>
+
+/*
+ * Test that meta-IRQs return to the cooperative thread they preempted.
+ *
+ * A meta-IRQ thread unblocks first a long-running low-priority
+ * cooperative thread, sleeps a little, and then unblocks a
+ * high-priority cooperative thread before the low-priority thread has
+ * finished. The correct behavior is to continue execution of the
+ * low-priority thread and schedule the high-priority thread
+ * afterwards.
+ */
+
+#if defined(CONFIG_SMP) && CONFIG_MP_NUM_CPUS > 1
+#error Meta-IRQ test requires single-CPU operation
+#endif
+
+#if CONFIG_NUM_METAIRQ_PRIORITIES < 1
+#error Need one metairq priority
+#endif
+
+#if CONFIG_NUM_COOP_PRIORITIES < 2
+#error Need two cooperative priorities
+#endif
+
+K_SEM_DEFINE(metairq_sem, 0, 1);
+K_SEM_DEFINE(coop_sem1, 0, 1);
+K_SEM_DEFINE(coop_sem2, 0, 1);
+
+/* Variables to track progress of cooperative threads */
+volatile int coop_cnt1;
+volatile int coop_cnt2;
+
+#define WAIT_MS  10 /* Time to wait/sleep between actions */
+#define LOOP_CNT  4 /* Number of times low priority thread waits */
+
+/* Meta-IRQ thread */
+void metairq_thread(void)
+{
+	k_sem_take(&metairq_sem, K_FOREVER);
+
+	printk("metairq start\n");
+
+	coop_cnt1 = 0;
+	coop_cnt2 = 0;
+
+	printk("give sem2\n");
+	k_sem_give(&coop_sem2);
+
+	k_sleep(WAIT_MS);
+
+	printk("give sem1\n");
+	k_sem_give(&coop_sem1);
+
+	printk("metairq end\n");
+
+	k_sem_give(&metairq_sem);
+}
+
+/* High-priority cooperative thread */
+void coop_thread1(void)
+{
+	k_sem_take(&coop_sem1, K_FOREVER);
+
+	/* Expect that low-priority thread has run to completion */
+	zassert_equal(coop_cnt1, 0,
+		      "Unexpected cnt1 at start: %d", coop_cnt1);
+	zassert_equal(coop_cnt2, LOOP_CNT,
+		      "Unexpected cnt2 at start: %d", coop_cnt2);
+
+	printk("thread1\n");
+	coop_cnt1++;
+
+	/* Expect that both threads have run to completion */
+	zassert_equal(coop_cnt1, 1,
+		      "Unexpected cnt1 at end: %d", coop_cnt1);
+	zassert_equal(coop_cnt2, LOOP_CNT,
+		      "Unexpected cnt2 at end: %d", coop_cnt2);
+
+	k_sem_give(&coop_sem1);
+}
+
+/* Low-priority cooperative thread */
+void coop_thread2(void)
+{
+	k_sem_take(&coop_sem2, K_FOREVER);
+
+	/* Expect that this is run first */
+	zassert_equal(coop_cnt1, 0,
+		      "Unexpected cnt1 at start: %d", coop_cnt1);
+	zassert_equal(coop_cnt2, 0,
+		      "Unexpected cnt2 at start: %d", coop_cnt2);
+
+	for (int i = 0; i < LOOP_CNT; i++) {
+		printk("thread2\n");
+		coop_cnt2++;
+		k_busy_wait(WAIT_MS * 1000);
+	}
+
+	/* Expect that this runs to completion before high-priority
+	 * thread is started
+	 */
+	zassert_equal(coop_cnt1, 0,
+		      "Unexpected cnt1 at end: %d", coop_cnt1);
+	zassert_equal(coop_cnt2, LOOP_CNT,
+		      "Unexpected cnt2 at end: %d", coop_cnt2);
+
+	k_sem_give(&coop_sem2);
+}
+
+K_THREAD_DEFINE(metairq_thread_id, 1024,
+		metairq_thread, 0, 0, 0,
+		K_PRIO_COOP(0), 0, K_NO_WAIT);
+K_THREAD_DEFINE(coop_thread1_id, 1024,
+		coop_thread1, 0, 0, 0,
+		K_PRIO_COOP(1), 0, K_NO_WAIT);
+K_THREAD_DEFINE(coop_thread2_id, 1024,
+		coop_thread2, 0, 0, 0,
+		K_PRIO_COOP(2), 0, K_NO_WAIT);
+
+void test_preempt(void)
+{
+	/* Kick off meta-IRQ */
+	k_sem_give(&metairq_sem);
+
+	/* Wait for all threads to finish */
+	k_sem_take(&coop_sem2, K_FOREVER);
+	k_sem_take(&coop_sem1, K_FOREVER);
+	k_sem_take(&metairq_sem, K_FOREVER);
+}
+
+void test_main(void)
+{
+	ztest_test_suite(suite_preempt,
+			 ztest_unit_test(test_preempt));
+	ztest_run_test_suite(suite_preempt);
+}

tests/kernel/sched/metairq/testcase.yaml

@@ -0,0 +1,5 @@
+tests:
+  kernel.sched.metairq:
+    tags: kernel
+    filter: not CONFIG_SMP
+    platform_exclude: nrf52810_pca10040