From 88af14b528ebbe9ed1aa7300aaa8d34409c43363 Mon Sep 17 00:00:00 2001
From: Martine Lenders <m.lenders@fu-berlin.de>
Date: Wed, 30 Jan 2019 17:15:06 +0100
Subject: [PATCH] fixup! tests: add tests to reproduce #10881

---
 tests/thread_msg_block_race/Makefile |  1 +
 tests/thread_msg_block_race/main.c   | 53 +++++++++++-----------------
 2 files changed, 22 insertions(+), 32 deletions(-)

diff --git a/tests/thread_msg_block_race/Makefile b/tests/thread_msg_block_race/Makefile
index 25ad0a900146..6bfda01fa8ac 100644
--- a/tests/thread_msg_block_race/Makefile
+++ b/tests/thread_msg_block_race/Makefile
@@ -4,6 +4,7 @@ BOARD_INSUFFICIENT_MEMORY := nucleo-f031k6
 
 DISABLE_MODULE += auto_init
 FEATURES_REQUIRED += periph_timer
+USEMODULE += random
 
 TEST_ON_CI_WHITELIST += all
 
diff --git a/tests/thread_msg_block_race/main.c b/tests/thread_msg_block_race/main.c
index e3cf84dd9a07..bcc42e9cde48 100644
--- a/tests/thread_msg_block_race/main.c
+++ b/tests/thread_msg_block_race/main.c
@@ -21,53 +21,45 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
+#include "random.h"
 #include "thread.h"
 #include "msg.h"
 #include "xtimer.h"
 
-#define CANARY_TYPE     (0x21fd)
+#define CANARY_TYPE         (0x21fd)
 
-#define TIMER_FREQ      (1000000LU)
-#define TIMER_TIMEOUT   (1U)
+#define TIMER_FREQ          (1000000LU)
+#define TIMER_TIMEOUT_MIN   (1U)
+#define TIMER_TIMEOUT_MAX   (100U)
 
-static char _t1_stack[THREAD_STACKSIZE_DEFAULT];
-static char _t2_stack[THREAD_STACKSIZE_DEFAULT];
-
-static mutex_t _mutex = MUTEX_INIT_LOCKED;
+static char _stack[THREAD_STACKSIZE_DEFAULT];
 
 static kernel_pid_t _pid_main = KERNEL_PID_UNDEF;
 
-static void _timer(void *arg, int channel)
+static void _sched_next(void)
 {
-    (void)arg;
-    (void)channel;
-    /* do context switch */
-    mutex_unlock(&_mutex);
-    timer_set(TIMER_DEV(0), 0, TIMER_TIMEOUT);
+    timer_set(TIMER_DEV(0), 0, random_uint32_range(TIMER_TIMEOUT_MIN,
+                                                   TIMER_TIMEOUT_MAX));
 }
 
-static void *_thread1(void *arg)
+static void _timer(void *arg, int channel)
 {
-    (void) arg;
-
-    while (1) {
-        mutex_lock(&_mutex);
-        puts("nr1");
-    }
-
-    return NULL;
+    (void)arg;
+    (void)channel;
+    _sched_next();
 }
 
-static void *_thread2(void *arg)
+static void *_thread(void *arg)
 {
     (void) arg;
 
     while (1) {
         msg_t msg = { .type = 0U };
 
-        msg_try_send(&msg, _pid_main);
-        puts("nr2");
+        write(STDOUT_FILENO, ".", 1U);
+        msg_send(&msg, _pid_main);
     }
 
     return NULL;
@@ -78,14 +70,12 @@ int main(void)
     kernel_pid_t pid;
 
     timer_init(TIMER_DEV(0), TIMER_FREQ, _timer, NULL);
+    random_init(timer_read(TIMER_DEV(0)));
     puts("Test is \"successful\" if it runs forever without crashing");
     _pid_main = sched_active_pid;
-    timer_set(TIMER_DEV(0), 0, TIMER_TIMEOUT);
-    pid = thread_create(_t1_stack, sizeof(_t1_stack), THREAD_PRIORITY_MAIN - 2,
-                        THREAD_CREATE_STACKTEST, _thread1, NULL, "nr1");
-    assert(pid != KERNEL_PID_UNDEF);
-    pid = thread_create(_t2_stack, sizeof(_t2_stack), THREAD_PRIORITY_MAIN - 1,
-                        THREAD_CREATE_STACKTEST, _thread2, NULL, "nr2");
+    _sched_next();
+    pid = thread_create(_stack, sizeof(_stack), THREAD_PRIORITY_MAIN - 1,
+                        THREAD_CREATE_STACKTEST, _thread, NULL, "nr2");
     assert(pid != KERNEL_PID_UNDEF);
 
     while (1) {
@@ -93,7 +83,6 @@ int main(void)
 
         msg_receive(&msg);
         assert(msg.type != CANARY_TYPE);
-        puts("main");
     }
     return 0;
 }