From dda168fc102843484a06b1b11e230f8fef8d4dc0 Mon Sep 17 00:00:00 2001
From: Stefan Kalkowski <stefan.kalkowski@genode-labs.com>
Date: Fri, 2 Sep 2022 13:35:13 +0200
Subject: [PATCH] platform API: simplify _wait_for_device

Fix genodelabs/genode#4615
---
 .../os/include/platform_session/connection.h  | 28 ++++++++-----------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/repos/os/include/platform_session/connection.h b/repos/os/include/platform_session/connection.h
index 350c8c7a1d..fbfa62a024 100644
--- a/repos/os/include/platform_session/connection.h
+++ b/repos/os/include/platform_session/connection.h
@@ -39,10 +39,11 @@ class Platform::Connection : public Genode::Connection<Session>,
 		friend class Device;
 		friend class Dma_buffer;
 
-		Env                                         &_env;
-		Rom_session_client                           _rom {devices_rom()};
-		Constructible<Attached_dataspace>            _ds  {};
-		Constructible<Io_signal_handler<Connection>> _handler {};
+		Env                             & _env;
+		Rom_session_client                _rom     { devices_rom() };
+		Constructible<Attached_dataspace> _ds      {};
+		Io_signal_handler<Connection>     _handler { _env.ep(), *this,
+		                                             &Connection::_handle_io };
 
 		void _try_attach()
 		{
@@ -60,19 +61,8 @@ class Platform::Connection : public Genode::Connection<Session>,
 			for (;;) {
 				/* repeatedly check for availability of device */
 				Capability<Device_interface> cap = fn();
-				if (cap.valid()) {
-					if (_handler.constructed()) {
-						sigh(Signal_context_capability());
-						_handler.destruct();
-					}
+				if (cap.valid())
 					return cap;
-				}
-
-				if (!_handler.constructed()) {
-					_handler.construct(_env.ep(), *this,
-					                   &Connection::_handle_io);
-					sigh(*_handler);
-				}
 
 				_env.ep().wait_and_dispatch_one_io_signal();
 			}
@@ -89,6 +79,12 @@ class Platform::Connection : public Genode::Connection<Session>,
 			_env(env)
 		{
 			_try_attach();
+
+			/*
+			 * Initially register dummy handler, to be able to receive signals
+			 * if _wait_for_device probes for a valid devices rom
+			 */
+			sigh(_handler);
 		}
 
 		void update()