From 40bf85e204eaeec700eb2211113de25c69a153d8 Mon Sep 17 00:00:00 2001
From: JulianHolzwarth <julian.holzwarth@fu-berlin.de>
Date: Fri, 24 May 2019 15:24:18 +0200
Subject: [PATCH] core/mutex.c _mutex_lock uses int pointer

_mutex_lock uses pointer
instead of int for blocking because of a possible interupt before the interupts are disabled

The int pointer is volitile.
Error in sys/xtimer/xtimer.c: _mutex_lock() will get fixed in next commit.
---
 core/include/mutex.h | 9 ++++++---
 core/mutex.c         | 4 ++--
 sys/xtimer/xtimer.c  | 3 ++-
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/core/include/mutex.h b/core/include/mutex.h
index f41a5ae9bc65a..5ed8c0624976d 100644
--- a/core/include/mutex.h
+++ b/core/include/mutex.h
@@ -23,6 +23,7 @@
 #define MUTEX_H
 
 #include <stddef.h>
+#include <stdint.h>
 
 #include "list.h"
 
@@ -87,7 +88,7 @@ static inline void mutex_init(mutex_t *mutex)
  * @return 1 if mutex was unlocked, now it is locked.
  * @return 0 if the mutex was locked.
  */
-int _mutex_lock(mutex_t *mutex, int blocking);
+int _mutex_lock(mutex_t *mutex, volatile uint8_t *blocking);
 
 /**
  * @brief Tries to get a mutex, non-blocking.
@@ -100,7 +101,8 @@ int _mutex_lock(mutex_t *mutex, int blocking);
  */
 static inline int mutex_trylock(mutex_t *mutex)
 {
-    return _mutex_lock(mutex, 0);
+    uint8_t blocking = 0;
+    return _mutex_lock(mutex, &blocking);
 }
 
 /**
@@ -110,7 +112,8 @@ static inline int mutex_trylock(mutex_t *mutex)
  */
 static inline void mutex_lock(mutex_t *mutex)
 {
-    _mutex_lock(mutex, 1);
+    uint8_t blocking = 1;
+    _mutex_lock(mutex, &blocking);
 }
 
 /**
diff --git a/core/mutex.c b/core/mutex.c
index cdc82d8b2cc80..1a24b4da6ad8f 100644
--- a/core/mutex.c
+++ b/core/mutex.c
@@ -32,7 +32,7 @@
 #define ENABLE_DEBUG    (0)
 #include "debug.h"
 
-int _mutex_lock(mutex_t *mutex, int blocking)
+int _mutex_lock(mutex_t *mutex, volatile uint8_t *blocking)
 {
     unsigned irqstate = irq_disable();
 
@@ -46,7 +46,7 @@ int _mutex_lock(mutex_t *mutex, int blocking)
         irq_restore(irqstate);
         return 1;
     }
-    else if (blocking) {
+    else if (*blocking) {
         thread_t *me = (thread_t*)sched_active_thread;
         DEBUG("PID[%" PRIkernel_pid "]: Adding node to mutex queue: prio: %"
               PRIu32 "\n", sched_active_pid, (uint32_t)me->priority);
diff --git a/sys/xtimer/xtimer.c b/sys/xtimer/xtimer.c
index 85762280848f7..ce09051018837 100644
--- a/sys/xtimer/xtimer.c
+++ b/sys/xtimer/xtimer.c
@@ -247,6 +247,7 @@ static void _mutex_timeout(void *arg)
     unsigned int irqstate = irq_disable();
 
     mutex_thread_t *mt = (mutex_thread_t *)arg;
+
     mt->blocking = 0;
     _mutex_remove_thread_from_waiting_queue(mt->mutex, mt->thread, &mt->dequeued);
     irq_restore(irqstate);
@@ -262,7 +263,7 @@ int xtimer_mutex_lock_timeout(mutex_t *mutex, uint64_t timeout)
         t.arg = (void *)((mutex_thread_t *)&mt);
         xtimer_set64(&t, timeout);
     }
-    int ret = _mutex_lock(mutex, mt.blocking);
+    int ret = _mutex_lock(mutex, &mt.blocking);
     if (ret == 0) {
         return -1;
     }