hw: simplify return value of Kernel::resume_thread

ref #1101

base-hw/include/kernel/interface.h

@@ -95,18 +95,13 @@ namespace Kernel
 
 
 	/**
-	 * Let an already started thread participate in CPU scheduling
+	 * Cancel blocking of a thread if possible
 	 *
 	 * \param thread_id  kernel name of the targeted thread
 	 *
-	 * \retval  0  succeeded and thread was paused beforehand
-	 * \retval  1  succeeded and thread was active beforehand
-	 * \retval -1  failed
-	 *
-	 * If the targeted thread blocks for any event except a 'start_thread'
-	 * call this call cancels the blocking.
+	 * \return  wether thread was in a cancelable blocking beforehand
 	 */
-	inline int resume_thread(unsigned const thread_id)
+	inline bool resume_thread(unsigned const thread_id)
 	{
 		return call(call_id_resume_thread(), thread_id);
 	}

base-hw/src/base/lock/lock_helper.h

@@ -52,7 +52,7 @@ static inline void thread_switch_to(Genode::Thread_base * const t)
 static inline bool
 thread_check_stopped_and_restart(Genode::Thread_base * const t)
 {
-	return Kernel::resume_thread(native_thread_id(t)) == 0;
+	return Kernel::resume_thread(native_thread_id(t));
 }
 
 

base-hw/src/core/kernel/thread.cc

@@ -129,28 +129,24 @@ void Thread::_await_ipc_failed()
 }
 
 
-int Thread::_resume()
+bool Thread::_resume()
 {
 	switch (_state) {
 	case AWAITS_RESUME:
 		_schedule();
-		return 0;
-	case SCHEDULED:
-		return 1;
+		return true;
 	case AWAITS_IPC:
 		Ipc_node::cancel_waiting();
-		return 0;
+		return true;
 	case AWAITS_SIGNAL:
 		Signal_handler::cancel_waiting();
-		return 0;
+		return true;
 	case AWAITS_SIGNAL_CONTEXT_KILL:
 		Signal_context_killer::cancel_waiting();
-		return 0;
-	case AWAITS_START:
-	case STOPPED:;
+		return true;
+	default:
+		return false;
 	}
-	PWRN("failed to resume thread");
-	return -1;
 }
 
 
@@ -412,20 +408,20 @@ void Thread::_call_pause_thread()
 void Thread::_call_resume_thread()
 {
 	/* lookup thread */
-	Thread * const t = Thread::pool()->object(user_arg_1());
-	if (!t) {
-		PWRN("unknown thread");
-		user_arg_0(-1);
+	Thread * const thread = Thread::pool()->object(user_arg_1());
+	if (!thread) {
+		PWRN("failed to lookup thread");
+		user_arg_0(false);
 		return;
 	}
 	/* check permissions */
-	if (!_core() && pd_id() != t->pd_id()) {
+	if (!_core() && pd_id() != thread->pd_id()) {
 		PWRN("not entitled to resume thread");
-		user_arg_0(-1);
+		_stop();
 		return;
 	}
-	/* resume targeted thread */
-	user_arg_0(t->_resume());
+	/* resume thread */
+	user_arg_0(thread->_resume());
 }
 
 

base-hw/src/core/kernel/thread.h

@@ -152,13 +152,11 @@ class Kernel::Thread
 		void _stop();
 
 		/**
-		 * Try to escape from blocking state, if in any, and resume execution
+		 * Cancel blocking if possible
 		 *
-		 * \retval -1  failed
-		 * \retval  0  succeeded, execution was paused
-		 * \retval  1  succeeded, execution was not paused
+		 * \return  wether thread was in a cancelable blocking beforehand
 		 */
-		int _resume();
+		bool _resume();
 
 		/**
 		 * Handle an exception thrown by the memory management unit