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Commit a95d8381 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Greg Kroah-Hartman
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ALSA: seq-dummy: remove deadlock-causing events on close 



commit 0767e95bb96d7fdddcd590fb809e6975d93aebc5 upstream.

When the last subscriber to a "Through" port has been removed, the
subscribed destination ports might still be active, so it would be
wrong to send "all sounds off" and "reset controller" events to them.
The proper place for such a shutdown would be the closing of the actual
MIDI port (and close_substream() in rawmidi.c already can do this).

This also fixes a deadlock when dummy_unuse() tries to send events to
its own port that is already locked because it is being freed.

Reported-by: default avatarPeter Billam <peter@www.pjb.com.au>
Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 71708851

sound/core/seq/seq_dummy.c

+0 −31
Original line number Diff line number Diff line
@@ -81,36 +81,6 @@ struct snd_seq_dummy_port { 


static int my_client = -1;



/*

 * unuse callback - send ALL_SOUNDS_OFF and RESET_CONTROLLERS events

 * to subscribers.

 * Note: this callback is called only after all subscribers are removed.

 */

static int

dummy_unuse(void *private_data, struct snd_seq_port_subscribe *info)

{

	struct snd_seq_dummy_port *p;

	int i;

	struct snd_seq_event ev;



	p = private_data;

	memset(&ev, 0, sizeof(ev));

	if (p->duplex)

		ev.source.port = p->connect;

	else

		ev.source.port = p->port;

	ev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;

	ev.type = SNDRV_SEQ_EVENT_CONTROLLER;

	for (i = 0; i < 16; i++) {

		ev.data.control.channel = i;

		ev.data.control.param = MIDI_CTL_ALL_SOUNDS_OFF;

		snd_seq_kernel_client_dispatch(p->client, &ev, 0, 0);

		ev.data.control.param = MIDI_CTL_RESET_CONTROLLERS;

		snd_seq_kernel_client_dispatch(p->client, &ev, 0, 0);

	}

	return 0;

}



/*

 * event input callback - just redirect events to subscribers

 */
@@ -175,7 +145,6 @@ create_port(int idx, int type) 
		| SNDRV_SEQ_PORT_TYPE_PORT;

	memset(&pcb, 0, sizeof(pcb));

	pcb.owner = THIS_MODULE;

	pcb.unuse = dummy_unuse;

	pcb.event_input = dummy_input;

	pcb.private_free = dummy_free;

	pcb.private_data = rec;