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From:   Yun-hao Chung <howardchung@google.com>
Date:   Mon, 12 Jul 2021 11:56:19 +0800
Message-ID: <CAPHZWUc1veeRnhhbV-a+Pc1+d6xjXCauA_mrs+rMddn7=MYY7g@mail.gmail.com>
Subject: Re: [Bluez PATCH v1 05/14] core: add device state and state callbacks
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        Yun-Hao Chung <howardchung@chromium.org>,
        Miao-chen Chou <mcchou@chromium.org>
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On Fri, Jul 9, 2021 at 1:34 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Howard,
>
> On Wed, Jul 7, 2021 at 11:23 PM Howard Chung <howardchung@google.com> wrote:
> >
> > From: Yun-Hao Chung <howardchung@chromium.org>
> >
> > This implements functions to register/unregister state changed callback
> > functions, the functions will be called when a device's state changed.
> > Currently the state only shows initializing, available and removing,
> > which is enough for plugins to register dbus objects upon device
> > creation and unregister it upon device removal.
> >
> > Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
> > ---
> >
> >  src/device.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  src/device.h | 13 +++++++++++
> >  2 files changed, 77 insertions(+)
> >
> > diff --git a/src/device.c b/src/device.c
> > index e1d82eab0988..0d7444706336 100644
> > --- a/src/device.c
> > +++ b/src/device.c
> > @@ -81,6 +81,13 @@
> >
> >  static DBusConnection *dbus_conn = NULL;
> >  static unsigned service_state_cb_id;
> > +static GSList *device_state_callbacks;
>
> Use a struct queue instead of GSList.
Will do.
>
> > +
> > +struct device_state_callback {
> > +       btd_device_state_cb     cb;
> > +       void                    *user_data;
> > +       unsigned int            id;
> > +};
> >
> >  struct btd_disconnect_data {
> >         guint id;
> > @@ -272,6 +279,8 @@ struct btd_device {
> >
> >         GIOChannel      *att_io;
> >         guint           store_id;
> > +
> > +       enum btd_device_state_t state;
> >  };
> >
> >  static const uint16_t uuid_list[] = {
> > @@ -4095,6 +4104,23 @@ static void gatt_service_removed(struct gatt_db_attribute *attr,
> >         gatt_services_changed(device);
> >  }
> >
> > +static void device_change_state(struct btd_device *device,
> > +                                       enum btd_device_state_t new_state)
> > +{
> > +       GSList *l;
> > +       struct device_state_callback *cb_data;
> > +
> > +       if (device->state == new_state)
> > +               return;
> > +
> > +       for (l = device_state_callbacks; l != NULL; l = g_slist_next(l)) {
> > +               cb_data = l->data;
> > +               cb_data->cb(device, new_state, cb_data->user_data);
> > +       }
> > +
> > +       device->state = new_state;
> > +}
> > +
> >  static struct btd_device *device_new(struct btd_adapter *adapter,
> >                                 const char *address)
> >  {
> > @@ -4158,6 +4184,8 @@ static struct btd_device *device_new(struct btd_adapter *adapter,
> >
> >         device->refresh_discovery = btd_opts.refresh_discovery;
> >
> > +       device_change_state(device, BTD_DEVICE_STATE_AVAILABLE);
> > +
> >         return btd_device_ref(device);
> >  }
> >
> > @@ -6839,6 +6867,7 @@ void btd_device_unref(struct btd_device *device)
> >
> >         DBG("Freeing device %s", device->path);
> >
> > +       device_change_state(device, BTD_DEVICE_STATE_REMOVING);
> >         g_dbus_unregister_interface(dbus_conn, device->path, DEVICE_INTERFACE);
> >  }
> >
> > @@ -6980,3 +7009,38 @@ void btd_device_cleanup(void)
> >  {
> >         btd_service_remove_state_cb(service_state_cb_id);
> >  }
> > +
> > +unsigned int btd_device_add_state_cb(btd_device_state_cb cb, void *user_data)
> > +{
> > +       struct device_state_callback *cb_data;
> > +       static unsigned int id;
> > +
> > +       cb_data = g_new0(struct device_state_callback, 1);
> > +       cb_data->cb = cb;
> > +       cb_data->user_data = user_data;
> > +       cb_data->id = ++id;
> > +
> > +       device_state_callbacks = g_slist_append(device_state_callbacks,
> > +                                                               cb_data);
> > +
> > +       return cb_data->id;
> > +}
> > +
> > +bool btd_device_remove_state_cb(unsigned int id)
> > +{
> > +       GSList *l;
> > +
> > +       for (l = device_state_callbacks; l != NULL; l = g_slist_next(l)) {
> > +               struct device_state_callback *cb_data = l->data;
> > +
> > +               if (cb_data && cb_data->id == id) {
> > +                       device_state_callbacks = g_slist_remove(
> > +                                                       device_state_callbacks,
> > +                                                       cb_data);
> > +                       g_free(cb_data);
> > +                       return true;
> > +               }
> > +       }
> > +
> > +       return false;
> > +}
> > diff --git a/src/device.h b/src/device.h
> > index 5f615cb4b6b2..a8424aa4f098 100644
> > --- a/src/device.h
> > +++ b/src/device.h
> > @@ -11,8 +11,18 @@
> >
> >  #define DEVICE_INTERFACE       "org.bluez.Device1"
> >
> > +enum btd_device_state_t {
> > +       BTD_DEVICE_STATE_INITIALIZING,  /* Device object is creating */
> > +       BTD_DEVICE_STATE_AVAILABLE,     /* Device object is registered */
> > +       BTD_DEVICE_STATE_REMOVING,      /* Device object is being removed */
> > +};
>
> I got a bad feeling about adding this sort of state, are you trying to
> cover some use case that we can't do with btd_service_add_state_cb? It
> does seem a lot like it but at device level.
I added this so that the admin plugin can know whenever a device
object is created or removed.
I just learned that we can create a dbus client to listen for new
device objects. If it sounds better, I'll do it in this way.
>
> > +
> >  struct btd_device;
> >
> > +typedef void (*btd_device_state_cb) (struct btd_device *device,
> > +                                       enum btd_device_state_t new_state,
> > +                                       void *user_data);
> > +
> >  struct btd_device *device_create(struct btd_adapter *adapter,
> >                                 const bdaddr_t *address, uint8_t bdaddr_type);
> >  struct btd_device *device_create_from_storage(struct btd_adapter *adapter,
> > @@ -179,3 +189,6 @@ bool btd_device_all_services_allowed(struct btd_device *dev);
> >  void btd_device_update_allowed_services(struct btd_device *dev);
> >  void btd_device_init(void);
> >  void btd_device_cleanup(void);
> > +
> > +unsigned int btd_device_add_state_cb(btd_device_state_cb cb, void *user_data);
> > +bool btd_device_remove_state_cb(unsigned int id);
> > --
> > 2.32.0.93.g670b81a890-goog
> >
>
>
> --
> Luiz Augusto von Dentz