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ALSA: seq-dummy: remove deadlock-causing events on close 

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: Peter Billam <peter@www.pjb.com.au>
Cc: <stable@vger.kernel.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2015-01-25 14:34:29 +01:00 committed by Takashi Iwai
parent 6715f728c8
commit 0767e95bb9
1 changed files with 0 additions and 31 deletions
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31
sound/core/seq/seq_dummy.c
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@ -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;