fix(kernel): properly release mutexes in _thread_detach_from_mutex()

Author: eatvector

include/rtthread.h

@@ -465,6 +465,7 @@ rt_err_t rt_mutex_trytake(rt_mutex_t mutex);
 rt_err_t rt_mutex_take_interruptible(rt_mutex_t mutex, rt_int32_t time);
 rt_err_t rt_mutex_take_killable(rt_mutex_t mutex, rt_int32_t time);
 rt_err_t rt_mutex_release(rt_mutex_t mutex);
+rt_err_t rt_mutex_force_release(rt_mutex_t mutex);
 rt_err_t rt_mutex_control(rt_mutex_t mutex, int cmd, void *arg);
 
 rt_inline rt_thread_t rt_mutex_get_owner(rt_mutex_t mutex)

src/ipc.c

@@ -1578,15 +1578,15 @@ RTM_EXPORT(rt_mutex_trytake);
  * @brief    This function will release a mutex. If there is thread suspended on the mutex, the thread will be resumed.
  *
  * @note     If there are threads suspended on this mutex, the first thread in the list of this mutex object
- *           will be resumed, and a thread scheduling (rt_schedule) will be executed.
+ *           will be resumed.
  *           If no threads are suspended on this mutex, the count value mutex->value of this mutex will increase by 1.
+ *           This operation requires mutex->spinlock to be held.
  *
  * @param    mutex is a pointer to a mutex object.
  *
- * @return   Return the operation status. When the return value is RT_EOK, the operation is successful.
- *           If the return value is any other values, it means that the mutex release failed.
+ * @return   Return RT_TRUE if scheduling is needed, RT_FALSE otherwise.
  */
-rt_err_t rt_mutex_release(rt_mutex_t mutex)
+static rt_err_t _rt_mutex_release(rt_mutex_t mutex, rt_bool_t is_force)
 {
     rt_sched_lock_level_t slvl;
     struct rt_thread *thread;
@@ -1612,11 +1612,15 @@ rt_err_t rt_mutex_release(rt_mutex_t mutex)
     RT_OBJECT_HOOK_CALL(rt_object_put_hook, (&(mutex->parent.parent)));
 
     /* mutex only can be released by owner */
-    if (thread != mutex->owner)
+    if (is_force)
+    {
+        /* Force release by setting hold count to 1 */
+        mutex->hold = 1;
+    }
+    else if (thread != mutex->owner) 
     {
         thread->error = -RT_ERROR;
         rt_spin_unlock(&(mutex->spinlock));
-
         return -RT_ERROR;
     }
 
@@ -1713,9 +1717,31 @@ rt_err_t rt_mutex_release(rt_mutex_t mutex)
 
     return RT_EOK;
 }
-RTM_EXPORT(rt_mutex_release);
 
 
+rt_err_t rt_mutex_force_release(rt_mutex_t mutex)
+{
+    return _rt_mutex_release(mutex, RT_TRUE);
+}
+
+
+/**
+ * @brief    Release a mutex owned by current thread.
+ *
+ * @note     Resumes first suspended thread if any (requires scheduling).
+ *           Increases mutex->value if no threads waiting.
+ *           Must be called by mutex owner with spinlock held.
+ *
+ * @param    mutex Pointer to the mutex object.
+ *
+ * @return   RT_EOK on success, -RT_ERROR if not owner.
+ */
+rt_err_t rt_mutex_release(rt_mutex_t mutex)
+{
+    return _rt_mutex_release(mutex, RT_FALSE);
+}
+RTM_EXPORT(rt_mutex_release);
+
 /**
  * @brief    This function will set some extra attributions of a mutex object.
  *

src/thread.c

@@ -77,6 +77,7 @@ RT_OBJECT_HOOKLIST_DEFINE(rt_thread_inited);
 #endif /* defined(RT_USING_HOOK) && defined(RT_HOOK_USING_FUNC_PTR) */
 
 #ifdef RT_USING_MUTEX
+
 static void _thread_detach_from_mutex(rt_thread_t thread)
 {
     rt_list_t *node;
@@ -101,9 +102,7 @@ static void _thread_detach_from_mutex(rt_thread_t thread)
     {
         mutex = rt_list_entry(node, struct rt_mutex, taken_list);
         LOG_D("Thread [%s] exits while holding mutex [%s].\n", thread->parent.name, mutex->parent.parent.name);
-        /* recursively take */
-        mutex->hold = 1;
-        rt_mutex_release(mutex);
+        rt_mutex_force_release(mutex);
     }
 
     rt_spin_unlock_irqrestore(&thread->spinlock, level);