tests: Test k_reschedule() with deadline scheduler

Setting a deadline is not a schedule point. This makes it a
perfect place to verify the behavior of the new k_reschedule()
routine at both thread and ISR level.

Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>

Author: peter-mitsis

tests/kernel/sched/deadline/prj.conf

@@ -7,3 +7,6 @@ CONFIG_BT=n
 # Deadline is not compatible with MULTIQ, so we have to pick something
 # specific instead of using the board-level default.
 CONFIG_SCHED_DUMB=y
+
+CONFIG_IRQ_OFFLOAD=y
+CONFIG_IRQ_OFFLOAD_NESTED=n

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

@@ -13,7 +13,12 @@
  */
 #define STACK_SIZE (512 + CONFIG_TEST_EXTRA_STACK_SIZE)
 
+#define MSEC_TO_CYCLES(msec)  (int)(((uint64_t)(msec) * \
+				     (uint64_t)CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC) / \
+				    (uint64_t)MSEC_PER_SEC)
+
 struct k_thread worker_threads[NUM_THREADS];
+volatile struct k_thread *expected_thread;
 k_tid_t worker_tids[NUM_THREADS];
 
 K_THREAD_STACK_ARRAY_DEFINE(worker_stacks, NUM_THREADS, STACK_SIZE);
@@ -215,4 +220,105 @@ ZTEST(suite_deadline, test_unqueued)
 	}
 }
 
+#if (CONFIG_MP_MAX_NUM_CPUS == 1)
+static void reschedule_wrapper(const void *param)
+{
+	ARG_UNUSED(param);
+
+	k_reschedule();
+}
+
+static void test_reschedule_helper0(void *p1, void *p2, void *p3)
+{
+	/* 4. Reschedule brings us here */
+
+	zassert_true(expected_thread == arch_current_thread(), "");
+
+	expected_thread = &worker_threads[1];
+}
+
+static void test_reschedule_helper1(void *p1, void *p2, void *p3)
+{
+	void (*offload)(void (*f)(const void *p), const void *param) = p1;
+
+	/* 1. First helper expected to execute */
+
+	zassert_true(expected_thread == arch_current_thread(), "");
+
+	offload(reschedule_wrapper, NULL);
+
+	/* 2. Deadlines have not changed. Expected no changes */
+
+	zassert_true(expected_thread == arch_current_thread(), "");
+
+	k_thread_deadline_set(arch_current_thread(), MSEC_TO_CYCLES(1000));
+
+	/* 3. Deadline changed, but there was no reschedule */
+
+	zassert_true(expected_thread == arch_current_thread(), "");
+
+	expected_thread = &worker_threads[0];
+	offload(reschedule_wrapper, NULL);
+
+	/* 5. test_thread_reschedule_helper0 executed */
+
+	zassert_true(expected_thread == arch_current_thread(), "");
+}
+
+static void thread_offload(void (*f)(const void *p), const void *param)
+{
+	f(param);
+}
+
+ZTEST(suite_deadline, test_thread_reschedule)
+{
+	k_thread_create(&worker_threads[0], worker_stacks[0], STACK_SIZE,
+			test_reschedule_helper0,
+			thread_offload, NULL, NULL,
+			K_LOWEST_APPLICATION_THREAD_PRIO,
+			0, K_NO_WAIT);
+
+	k_thread_create(&worker_threads[1], worker_stacks[1], STACK_SIZE,
+			test_reschedule_helper1,
+			thread_offload, NULL, NULL,
+			K_LOWEST_APPLICATION_THREAD_PRIO,
+			0, K_NO_WAIT);
+
+	k_thread_deadline_set(&worker_threads[0], MSEC_TO_CYCLES(500));
+	k_thread_deadline_set(&worker_threads[1], MSEC_TO_CYCLES(10));
+
+	expected_thread = &worker_threads[1];
+
+	k_thread_join(&worker_threads[1], K_FOREVER);
+	k_thread_join(&worker_threads[0], K_FOREVER);
+
+#ifndef CONFIG_SMP
+	/*
+	 * When SMP is enabled, there is always a reschedule performed
+	 * at the end of the ISR.
+	 */
+	k_thread_create(&worker_threads[0], worker_stacks[0], STACK_SIZE,
+			test_reschedule_helper0,
+			irq_offload, NULL, NULL,
+			K_LOWEST_APPLICATION_THREAD_PRIO,
+			0, K_NO_WAIT);
+
+	k_thread_create(&worker_threads[1], worker_stacks[1], STACK_SIZE,
+			test_reschedule_helper1,
+			irq_offload, NULL, NULL,
+			K_LOWEST_APPLICATION_THREAD_PRIO,
+			0, K_NO_WAIT);
+
+	k_thread_deadline_set(&worker_threads[0], MSEC_TO_CYCLES(500));
+	k_thread_deadline_set(&worker_threads[1], MSEC_TO_CYCLES(10));
+
+	expected_thread = &worker_threads[1];
+
+	k_thread_join(&worker_threads[1], K_FOREVER);
+	k_thread_join(&worker_threads[0], K_FOREVER);
+
+#endif /* !CONFIG_SMP */
+}
+#endif /* CONFIG_MP_MAX_NUM_CPUS == 1 */
+
 ZTEST_SUITE(suite_deadline, NULL, NULL, NULL, NULL, NULL);