hw: destruct signal sessions

ref #589

base-hw/src/base/signal/signal.cc

@@ -21,7 +21,7 @@ using namespace Genode;
 
 
 /**
- * Provide a static signal connection
+ * Provide one signal connection per program
  */
 static Signal_connection * signal_connection()
 {
@@ -40,12 +40,10 @@ void Signal::_dec_ref_and_unlock()
 		Lock::Guard lock_guard(_data.context->_lock);
 		_data.context->_ref_cnt--;
 
-		/*
-		 * We must ack a signal context to receive the next one,
-		 * so new signals are received only when ref_cnt = 0.
-		 */
-		if (_data.context->_ref_cnt == 0)
+		/* acknowledge as soon as receipt is fully processed */
+		if (_data.context->_ref_cnt == 0) {
 			Kernel::ack_signal(_data.context->_cap.dst());
+		}
 	}
 }
 
@@ -61,11 +59,7 @@ void Signal::_inc_ref()
 
 Signal::Signal(Signal::Data data) : _data(data)
 {
-	/*
-	 * We assume that a kernel signal-context doesn't deliver
-	 * multiple signals simultaneously.
-	 */
-	if (_data.context) _data.context->_ref_cnt = 1;
+	if (_data.context) { _data.context->_ref_cnt = 1; }
 }
 
 
@@ -73,9 +67,8 @@ Signal::Signal(Signal::Data data) : _data(data)
  ** Signal transmitter **
  ************************/
 
-void Signal_transmitter::submit(unsigned cnt)
+void Signal_transmitter::submit(unsigned const cnt)
 {
-	/* submits to invalid signal contexts get ignored */
 	Kernel::submit_signal(_context.dst(), cnt);
 }
 
@@ -116,7 +109,7 @@ void Signal_receiver::_platform_destructor()
 }
 
 
-void Signal_receiver::_unsynchronized_dissolve(Signal_context * c)
+void Signal_receiver::_unsynchronized_dissolve(Signal_context * const c)
 {
 	/* release server resources of context */
 	signal_connection()->free_context(c->_cap);
@@ -196,5 +189,6 @@ Signal Signal_receiver::wait_for_signal()
 
 void Signal_receiver::local_submit(Signal::Data signal)
 {
-	PDBG("Not implemented");
+	PDBG("not implemented");
+	throw Exception();
 }

base-hw/src/core/include/signal_session_component.h

@@ -58,6 +58,16 @@ namespace Genode
 			char            _initial_receivers_sb [RECEIVERS_SB_SIZE];
 			char            _initial_contexts_sb  [CONTEXTS_SB_SIZE];
 
+			/**
+			 * Destruct receiver 'r'  
+			 */
+			void _destruct_receiver(Receiver * const r);
+
+			/**
+			 * Destruct context 'c'
+			 */
+			void _destruct_context(Context * const c);
+
 		public:
 
 			/**

base-hw/src/core/kernel.cc

@@ -596,7 +596,7 @@ namespace Kernel
 	{
 		/* check permissions */
 		if (user->pd_id() != core_id()) {
-			PERR("permission to create signal receiver denied");
+			PERR("not entitled to create signal receiver");
 			user->user_arg_0(0);
 			return;
 		}
@@ -622,7 +622,7 @@ namespace Kernel
 		unsigned id = user->user_arg_2();
 		Signal_receiver * const r = Signal_receiver::pool()->object(id);
 		if (!r) {
-			PERR("invalid signal receiver");
+			PERR("unknown signal receiver");
 			user->user_arg_0(0);
 			return;
 		}
@@ -649,12 +649,11 @@ namespace Kernel
 		unsigned id = user->user_arg_1();
 		Signal_receiver * const r = Signal_receiver::pool()->object(id);
 		if (!r) {
-			PERR("invalid signal receiver");
+			PERR("unknown signal receiver");
 			user->user_arg_0(-1);
 			return;
 		}
 		/* register handler at the receiver */
-		user->await_signal(r);
 		if (r->add_handler(user)) {
 			PERR("failed to register handler at signal receiver");
 			user->user_arg_0(-1);
@@ -673,7 +672,7 @@ namespace Kernel
 		unsigned id = user->user_arg_1();
 		Signal_receiver * const r = Signal_receiver::pool()->object(id);
 		if (!r) {
-			PERR("invalid signal receiver");
+			PERR("unknown signal receiver");
 			user->user_arg_0(0);
 			return;
 		}
@@ -691,12 +690,13 @@ namespace Kernel
 		unsigned const id = user->user_arg_1();
 		Signal_context * const c = Signal_context::pool()->object(id);
 		if(!c) {
-			PERR("invalid signal context");
+			PERR("unknown signal context");
 			user->user_arg_0(-1);
 			return;
 		}
 		/* trigger signal context */
 		if (c->submit(user->user_arg_2())) {
+			PERR("failed to submit signal context");
 			user->user_arg_0(-1);
 			return;
 		}
@@ -713,7 +713,7 @@ namespace Kernel
 		unsigned id = user->user_arg_1();
 		Signal_context * const c = Signal_context::pool()->object(id);
 		if (!c) {
-			PWRN("invalid signal context");
+			PERR("unknown signal context");
 			return;
 		}
 		/* acknowledge */
@@ -736,11 +736,13 @@ namespace Kernel
 		unsigned id = user->user_arg_1();
 		Signal_context * const c = Signal_context::pool()->object(id);
 		if (!c) {
+			PERR("unknown signal context");
 			user->user_arg_0(0);
 			return;
 		}
 		/* kill signal context */
 		if (c->kill(user)) {
+			PERR("failed to kill signal context");
 			user->user_arg_0(-1);
 			return;
 		}
@@ -760,15 +762,16 @@ namespace Kernel
 			return;
 		}
 		/* lookup signal receiver */
-		user->user_arg_0(1);
 		unsigned id = user->user_arg_1();
 		Signal_receiver * const r = Signal_receiver::pool()->object(id);
 		if (!r) {
+			PERR("unknown signal receiver");
 			user->user_arg_0(0);
 			return;
 		}
 		/* kill signal receiver */
 		if (r->kill(user)) {
+			PERR("unknown signal receiver");
 			user->user_arg_0(-1);
 			return;
 		}

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

@@ -58,7 +58,14 @@ class Kernel::Signal_handler
 
 		typedef Genode::Fifo_element<Signal_handler> Fifo_element;
 
-		Fifo_element   _handlers_fe;
+		Fifo_element _handlers_fe;
+
+		/**
+		 * Let the handler block for signal receipt
+		 *
+		 * \param receiver  the signal pool that the thread blocks for
+		 */
+		virtual void _await_signal(Signal_receiver * const receiver) = 0;
 
 		/**
 		 * Signal delivery backend
@@ -66,7 +73,7 @@ class Kernel::Signal_handler
 		 * \param base  signal-data base
 		 * \param size  signal-data size
 		 */
-		virtual void _signal_handler(void * const base, size_t const size) = 0;
+		virtual void _receive_signal(void * const base, size_t const size) = 0;
 
 	public:
 
@@ -267,7 +274,7 @@ class Kernel::Signal_receiver
 				Signal_handler * const h = _handlers.dequeue()->object();
 				Signal::Data data((Genode::Signal_context *)c->_imprint,
 				                   c->_submits);
-				h->_signal_handler(&data, sizeof(data));
+				h->_receive_signal(&data, sizeof(data));
 				c->_delivered();
 			}
 		}
@@ -317,6 +324,7 @@ class Kernel::Signal_receiver
 		{
 			if (_killer) { return -1; }
 			_handlers.enqueue(&h->_handlers_fe);
+			h->_await_signal(this);
 			_listen();
 			return 0;
 		}

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

@@ -143,7 +143,14 @@ class Kernel::Thread
 		 ** Signal_handler **
 		 ********************/
 
-		void _signal_handler(void * const base, size_t const size)
+		void _await_signal(Signal_receiver * const receiver)
+		{
+			cpu_scheduler()->remove(this);
+			_state = AWAIT_SIGNAL;
+			_signal_receiver = receiver;
+		}
+
+		void _receive_signal(void * const base, size_t const size)
 		{
 			assert(_state == AWAIT_SIGNAL && size <= phys_utcb()->size());
 			Genode::memcpy(phys_utcb()->base(), base, size);
@@ -392,18 +399,6 @@ class Kernel::Thread
 		 */
 		unsigned id() const { return Object::id(); }
 
-		/**
-		 * Let the thread block for signal receipt
-		 *
-		 * \param receiver  the signal pool that the thread blocks for
-		 */
-		void await_signal(Signal_receiver * receiver)
-		{
-			cpu_scheduler()->remove(this);
-			_state = AWAIT_SIGNAL;
-			_signal_receiver = receiver;
-		}
-
 
 		/***********************
 		 ** Execution_context **

base-hw/src/core/signal_session_component.cc

@@ -39,8 +39,16 @@ Signal_session_component::Signal_session_component(Allocator * const md,
 
 Signal_session_component::~Signal_session_component()
 {
-	PERR("%s: Not implemented", __PRETTY_FUNCTION__);
-	while (1) ;
+	while (1) {
+		Context * const c = _contexts.first_locked();
+		if (!c) { break; }
+		_destruct_context(c);
+	}
+	while (1) {
+		Receiver * const r = _receivers.first_locked();
+		if (!r) { break; }
+		_destruct_receiver(r);
+	}
 }
 
 
@@ -80,17 +88,8 @@ void Signal_session_component::free_receiver(Signal_receiver_capability cap)
 		PERR("unknown signal receiver");
 		throw Exception();
 	}
-	/* release kernel resources */
-	if (Kernel::kill_signal_receiver(r->id()))
-	{
-		/* clean-up */
-		r->release();
-		PERR("failed to kill signal receiver");
-		throw Exception();
-	}
-	/* release core resources */
-	_receivers.remove_locked(r);
-	r->~Receiver();
+	/* release resources */
+	_destruct_receiver(r);
 	_receivers_slab.free(r, Receiver::slab_size());
 }
 
@@ -132,6 +131,14 @@ void Signal_session_component::free_context(Signal_context_capability cap)
 		PERR("unknown signal context");
 		throw Exception();
 	}
+	/* release resources */
+	_destruct_context(c);
+	_contexts_slab.free(c, Context::slab_size());
+}
+
+
+void Signal_session_component::_destruct_context(Context * const c)
+{
 	/* release kernel resources */
 	if (Kernel::kill_signal_context(c->id()))
 	{
@@ -143,5 +150,20 @@ void Signal_session_component::free_context(Signal_context_capability cap)
 	/* release core resources */
 	_contexts.remove_locked(c);
 	c->~Context();
-	_contexts_slab.free(c, Context::slab_size());
+}
+
+
+void Signal_session_component::_destruct_receiver(Receiver * const r)
+{
+	/* release kernel resources */
+	if (Kernel::kill_signal_receiver(r->id()))
+	{
+		/* clean-up */
+		r->release();
+		PERR("failed to kill signal receiver");
+		throw Exception();
+	}
+	/* release core resources */
+	_receivers.remove_locked(r);
+	r->~Receiver();
 }