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Commit 59866da9 authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: usb-audio: Avoid autopm calls after disconnection 

Add a similar protection against the disconnection race and the
invalid use of usb instance after disconnection, as well as we've done
for the USB audio PCM.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51201



Reviewd-by: default avatarClemens Ladisch <clemens@ladisch.de>
Tested-by: default avatarClemens Ladisch <clemens@ladisch.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 467b1035

sound/usb/midi.c

+22 −1
Original line number Diff line number Diff line
@@ -116,6 +116,7 @@ struct snd_usb_midi { 
	struct list_head list;

	struct timer_list error_timer;

	spinlock_t disc_lock;

	struct rw_semaphore disc_rwsem;

	struct mutex mutex;

	u32 usb_id;

	int next_midi_device;
@@ -1038,6 +1039,12 @@ static void substream_open(struct snd_rawmidi_substream *substream, int open) 
	struct snd_usb_midi* umidi = substream->rmidi->private_data;

	struct snd_kcontrol *ctl;



	down_read(&umidi->disc_rwsem);

	if (umidi->disconnected) {

		up_read(&umidi->disc_rwsem);

		return;

	}



	mutex_lock(&umidi->mutex);

	if (open) {

		if (umidi->opened++ == 0 && umidi->roland_load_ctl) {
@@ -1056,6 +1063,7 @@ static void substream_open(struct snd_rawmidi_substream *substream, int open) 
		}

	}

	mutex_unlock(&umidi->mutex);

	up_read(&umidi->disc_rwsem);

}



static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream)
@@ -1076,8 +1084,15 @@ static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream) 
		snd_BUG();

		return -ENXIO;

	}



	down_read(&umidi->disc_rwsem);

	if (umidi->disconnected) {

		up_read(&umidi->disc_rwsem);

		return -ENODEV;

	}

	err = usb_autopm_get_interface(umidi->iface);

	port->autopm_reference = err >= 0;

	up_read(&umidi->disc_rwsem);

	if (err < 0 && err != -EACCES)

		return -EIO;

	substream->runtime->private_data = port;
@@ -1092,8 +1107,10 @@ static int snd_usbmidi_output_close(struct snd_rawmidi_substream *substream) 
	struct usbmidi_out_port *port = substream->runtime->private_data;



	substream_open(substream, 0);

	if (port->autopm_reference)

	down_read(&umidi->disc_rwsem);

	if (!umidi->disconnected && port->autopm_reference)

		usb_autopm_put_interface(umidi->iface);

	up_read(&umidi->disc_rwsem);

	return 0;

}
@@ -1403,9 +1420,12 @@ void snd_usbmidi_disconnect(struct list_head* p) 
	 * a timer may submit an URB. To reliably break the cycle

	 * a flag under lock must be used

	 */

	down_write(&umidi->disc_rwsem);

	spin_lock_irq(&umidi->disc_lock);

	umidi->disconnected = 1;

	spin_unlock_irq(&umidi->disc_lock);

	up_write(&umidi->disc_rwsem);



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

		struct snd_usb_midi_endpoint* ep = &umidi->endpoints[i];

		if (ep->out)
@@ -2117,6 +2137,7 @@ int snd_usbmidi_create(struct snd_card *card, 
	umidi->usb_protocol_ops = &snd_usbmidi_standard_ops;

	init_timer(&umidi->error_timer);

	spin_lock_init(&umidi->disc_lock);

	init_rwsem(&umidi->disc_rwsem);

	mutex_init(&umidi->mutex);

	umidi->usb_id = USB_ID(le16_to_cpu(umidi->dev->descriptor.idVendor),

			       le16_to_cpu(umidi->dev->descriptor.idProduct));