MIDI output and input are handled on different threads, so a mutex is
required to serialize access to the mio_hdl structure.

This diff fixes disconnection from sndiod caused by corruption of the
mio_hdl structure.

While we're at it, fix the input event loop to not stop if a signal is
received during poll(4). If so just recheck the m_quit flag and retry.

OK?

Index: Makefile
===================================================================
RCS file: /cvs/ports/audio/lmms/Makefile,v
diff -u -p -r1.28 Makefile
--- Makefile	5 Sep 2023 16:13:39 -0000	1.28
+++ Makefile	24 Apr 2025 13:20:42 -0000
@@ -5,7 +5,7 @@ DISTNAME =		lmms_$V
 PKGNAME =		lmms-$V
 WRKDIST =		${WRKDIR}/lmms
 EXTRACT_SUFX =		.tar.xz
-REVISION =		1
+REVISION =		2
 
 CATEGORIES =		audio
 
Index: patches/patch-include_MidiSndio_h
===================================================================
RCS file: patches/patch-include_MidiSndio_h
diff -N patches/patch-include_MidiSndio_h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ patches/patch-include_MidiSndio_h	24 Apr 2025 13:20:42 -0000
@@ -0,0 +1,19 @@
+Index: include/MidiSndio.h
+--- include/MidiSndio.h.orig
++++ include/MidiSndio.h
+@@ -32,6 +32,7 @@
+ 
+ #include <QtCore/QThread>
+ #include <QtCore/QFile>
++#include <QtCore/QMutex>
+ 
+ #include <sndio.h>
+ 
+@@ -64,6 +65,7 @@ class MidiSndio : public MidiClientRaw, public QThread
+ 	virtual void run(void);
+ 
+ private:
++	QMutex m_hdlMutex;
+ 	struct mio_hdl *m_hdl;
+ 	volatile bool m_quit;
+ } ;
Index: patches/patch-src_core_midi_MidiSndio_cpp
===================================================================
RCS file: patches/patch-src_core_midi_MidiSndio_cpp
diff -N patches/patch-src_core_midi_MidiSndio_cpp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_core_midi_MidiSndio_cpp	24 Apr 2025 13:20:42 -0000
@@ -0,0 +1,48 @@
+Index: src/core/midi/MidiSndio.cpp
+--- src/core/midi/MidiSndio.cpp.orig
++++ src/core/midi/MidiSndio.cpp
+@@ -42,6 +42,7 @@
+ 
+ MidiSndio::MidiSndio( void ) :
+ 	MidiClientRaw(),
++	m_hdlMutex(),
+ 	m_quit( false )
+ {
+ 	QString dev = probeDevice();
+@@ -86,7 +87,9 @@ QString MidiSndio::probeDevice( void )
+ 
+ void MidiSndio::sendByte( const unsigned char c )
+ {
++	m_hdlMutex.lock();
+ 	mio_write( m_hdl, &c, 1 );
++	m_hdlMutex.unlock();
+ }
+ 
+ 
+@@ -99,13 +102,22 @@ void MidiSndio::run( void )
+ 	int ret;
+ 	while( m_quit == false && m_hdl )
+ 	{
++		m_hdlMutex.lock();
+ 		nfds = mio_pollfd( m_hdl, &pfd, POLLIN );
++		m_hdlMutex.unlock();
+ 		ret = poll( &pfd, nfds, 100 );
+-		if ( ret < 0 )
++		if ( ret < 0 ) {
++			if (errno == EINTR)
++				continue;
+ 			break;
+-		if ( !ret || !( mio_revents( m_hdl, &pfd ) & POLLIN ) )
+-			continue;
+-		n = mio_read( m_hdl, buf, sizeof(buf) );
++		}
++		m_hdlMutex.lock();
++		if (mio_revents( m_hdl, &pfd ) & POLLIN) {
++			n = mio_read( m_hdl, buf, sizeof(buf) );
++		} else {
++			n = 0;
++		}		
++		m_hdlMutex.unlock();
+ 		if ( !n )
+ 		{
+ 			break;