ALSA: jack: Unregister input device at disconnection

The recent change in sysfs triggered a kernel WARNING at unloading a
sound driver like

  WARNING: CPU: 3 PID: 2247 at fs/sysfs/group.c:214 sysfs_remove_group+0xe8/0xf0()
  sysfs group ffffffff81ab7b20 not found for kobject 'event14'

for each jack instance.  It's because the unregistration of jack input
device is done in dev_free callback, which is called after
snd_card_disconnect().  Since device_unregister(card->card_dev) is
called in snd_card_disconnect(), the whole sysfs entries belonging to
card->card_dev have been already removed recursively.  Thus this
results in a warning as input_unregister_device() yet tries to
unregister the already removed sysfs entry.

For fixing this mess, we need to unregister the jack input device at
dev_disconnect callback so that it's called before unregistering the
card->card_dev.

Reviwed-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 16 insertions, 3 deletions

diff --git a/sound/core/jack.c b/sound/core/jack.c
index b35fe7345c20..8658578eb584 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -34,12 +34,12 @@ static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
         SW_LINEIN_INSERT,
 };
 
-static int snd_jack_dev_free(struct snd_device *device)
+static int snd_jack_dev_disconnect(struct snd_device *device)
 {
         struct snd_jack *jack = device->device_data;
 
-        if (jack->private_free)
-                jack->private_free(jack);
+        if (!jack->input_dev)
+                return 0;
 
         /* If the input device is registered with the input subsystem
          * then we need to use a different deallocator. */
@@ -47,6 +47,18 @@ static int snd_jack_dev_free(struct snd_device *device)
                 input_unregister_device(jack->input_dev);
         else
                 input_free_device(jack->input_dev);
+        jack->input_dev = NULL;
+        return 0;
+}
+
+static int snd_jack_dev_free(struct snd_device *device)
+{
+        struct snd_jack *jack = device->device_data;
+
+        if (jack->private_free)
+                jack->private_free(jack);
+
+        snd_jack_dev_disconnect(device);
 
         kfree(jack->id);
         kfree(jack);
@@ -110,6 +122,7 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
         static struct snd_device_ops ops = {
                 .dev_free = snd_jack_dev_free,
                 .dev_register = snd_jack_dev_register,
+                .dev_disconnect = snd_jack_dev_disconnect,
         };
 
         jack = kzalloc(sizeof(struct snd_jack), GFP_KERNEL);