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References: <20210708062314.245754-1-howardchung@google.com> <20210708142059.Bluez.v1.5.I699a3837a5a18d9f889635300f6c717879f19dd2@changeid>
In-Reply-To: <20210708142059.Bluez.v1.5.I699a3837a5a18d9f889635300f6c717879f19dd2@changeid>
From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Thu, 8 Jul 2021 22:34:28 -0700
Message-ID: <CABBYNZJie9UMrvLkdPPX1rU-7PXy0YHy9DJTrCAikaB_djx4uw@mail.gmail.com>
Subject: Re: [Bluez PATCH v1 05/14] core: add device state and state callbacks
To:     Howard Chung <howardchung@google.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        Yun-Hao Chung <howardchung@chromium.org>,
        Miao-chen Chou <mcchou@chromium.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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.

> +
> +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.

> +
>  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