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: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index eeefbce3873c11dc35a6e174c4ace79daeeaa8c1..c0054ee9389bcdef91cd97a27dfe95073dd768a9 100644 (file)
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -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));