ALSA: dice: fix wrong reference count for stream functionality at error path of rawmi...

In IEC 61883-6, several types of sampling data can be multiplexed into
payload of common isochronous packet (CIP). For typical audio and music
units, PCM samples and MIDI messages are multiplexed into one packet
streaming.

ALSA dice driver allows applications of rawmidi interface to start
packet streaming for transmission of MIDI messages. However at error
path, the reference count of stream functionality is not operated
correctly. This can brings a bug that packet streaming is not stopped
when all referrers release the count.

This commit fixes the bug.

Fixes: 3cd2c2d780a2 ("ALSA: dice: reserve/release isochronous resources in pcm.hw_params/hw_free callbacks")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/dice/dice-midi.c b/sound/firewire/dice/dice-midi.c
index 436f0c3c0fbba75ee5cedac70bece1bcb56dff3d..30a0b8200160e94f6a470dc0d3970277c1a82595 100644 (file)
--- a/sound/firewire/dice/dice-midi.c
+++ b/sound/firewire/dice/dice-midi.c
@@ -22,6 +22,8 @@ static int midi_open(struct snd_rawmidi_substream *substream)
        if (err >= 0) {
                ++dice->substreams_counter;
                err = snd_dice_stream_start_duplex(dice);
+               if (err < 0)
+                       --dice->substreams_counter;
        }
 
        mutex_unlock(&dice->mutex);