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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Thu, 10 Sep 2020 10:31:04 -0700
Message-ID: <CABBYNZK1nyC=hEHYwa03Q-urzk5WtJv9R-dnAmfpRvLJ0wOqKQ@mail.gmail.com>
Subject: Re: [BlueZ PATCH v1 1/7] adv_monitor: Introduce org.bluez.AdvertisementMonitorManager1
 interface
To:     Miao-chen Chou <mcchou@chromium.org>
Cc:     Bluetooth Kernel Mailing List <linux-bluetooth@vger.kernel.org>,
        Alain Michaud <alainm@chromium.org>,
        Manish Mandlik <mmandlik@chromium.org>,
        Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
        Howard Chung <howardchung@google.com>,
        Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Miao,

On Wed, Sep 9, 2020 at 9:52 PM Miao-chen Chou <mcchou@chromium.org> wrote:
>
> Hi Luiz,
>
> On Tue, Sep 8, 2020 at 10:19 AM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Miao,
> >
> > On Tue, Aug 18, 2020 at 3:30 PM Miao-chen Chou <mcchou@chromium.org> wrote:
> > >
> > > This introduces the org.bluez.AdvertisementMonitorManager1 without
> > > implementing handlers of methods and properties.
> > >
> > > The following test was performed.
> > > - Upon adapter registration, the info line of creating an ADV monitor
> > > manager gets printed, and system bus emits the interface events of
> > > org.bluez.AdvertisementMonitorManager1.
> > >
> > > Reviewed-by: Yun-Hao Chung <howardchung@google.com>
> > > Reviewed-by: Manish Mandlik <mmandlik@chromium.org>
> > > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > > ---
> > >
> > >  Makefile.am       |   3 +-
> > >  src/adapter.c     |  14 +++++
> > >  src/adapter.h     |   3 +
> > >  src/adv_monitor.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++
> > >  src/adv_monitor.h |  32 ++++++++++
> > >  5 files changed, 200 insertions(+), 1 deletion(-)
> > >  create mode 100644 src/adv_monitor.c
> > >  create mode 100644 src/adv_monitor.h
> > >
> > > diff --git a/Makefile.am b/Makefile.am
> > > index 7719c06f8..b14ee950e 100644
> > > --- a/Makefile.am
> > > +++ b/Makefile.am
> > > @@ -293,7 +293,8 @@ src_bluetoothd_SOURCES = $(builtin_sources) \
> > >                         src/gatt-client.h src/gatt-client.c \
> > >                         src/device.h src/device.c \
> > >                         src/dbus-common.c src/dbus-common.h \
> > > -                       src/eir.h src/eir.c
> > > +                       src/eir.h src/eir.c \
> > > +                       src/adv_monitor.h src/adv_monitor.c
> >
> > Id just name it monitor.{c, h}
> It'd be preferable to avoid confusion by specifying "adv_" as the
> prefix, since there is the other "monitor" (btmon) in BlueZ. Besides,
> we also name the corresponding system configuration values by
> "adv_monitor".

Actually btmon is a tool though, but perhaps you are saying it would
conflict with commit tagging/prefixing since we usually use monitor:
for btmon changes, that is a fair point. We could perhaps just with
advertising.c, but Im fine with adv_monitor as well.

> >
> > >  src_bluetoothd_LDADD = lib/libbluetooth-internal.la \
> > >                         gdbus/libgdbus-internal.la \
> > >                         src/libshared-glib.la \
> > > diff --git a/src/adapter.c b/src/adapter.c
> > > index 5e896a9f0..41e9de286 100644
> > > --- a/src/adapter.c
> > > +++ b/src/adapter.c
> > > @@ -77,6 +77,7 @@
> > >  #include "attrib-server.h"
> > >  #include "gatt-database.h"
> > >  #include "advertising.h"
> > > +#include "adv_monitor.h"
> > >  #include "eir.h"
> > >
> > >  #define ADAPTER_INTERFACE      "org.bluez.Adapter1"
> > > @@ -272,6 +273,8 @@ struct btd_adapter {
> > >         struct btd_gatt_database *database;
> > >         struct btd_adv_manager *adv_manager;
> > >
> > > +       struct btd_adv_monitor_manager *adv_monitor_manager;
> > > +
> > >         gboolean initialized;
> > >
> > >         GSList *pin_callbacks;
> > > @@ -6346,6 +6349,9 @@ static void adapter_remove(struct btd_adapter *adapter)
> > >         btd_adv_manager_destroy(adapter->adv_manager);
> > >         adapter->adv_manager = NULL;
> > >
> > > +       btd_adv_monitor_manager_destroy(adapter->adv_monitor_manager);
> > > +       adapter->adv_monitor_manager = NULL;
> > > +
> > >         g_slist_free(adapter->pin_callbacks);
> > >         adapter->pin_callbacks = NULL;
> > >
> > > @@ -8623,6 +8629,14 @@ static int adapter_register(struct btd_adapter *adapter)
> > >
> > >         adapter->adv_manager = btd_adv_manager_new(adapter, adapter->mgmt);
> > >
> > > +       adapter->adv_monitor_manager = btd_adv_monitor_manager_create(
> > > +                                                       adapter, adapter->mgmt);
> > > +       if (!adapter->adv_monitor_manager) {
> > > +               btd_error(adapter->dev_id,
> > > +                       "Failed to create Adv Monitor Manager for adapter");
> > > +               return -EINVAL;
> > > +       }
> > > +
> > >         db = btd_gatt_database_get_db(adapter->database);
> > >         adapter->db_id = gatt_db_register(db, services_modified,
> > >                                                         services_modified,
> > > diff --git a/src/adapter.h b/src/adapter.h
> > > index f8ac20261..5cb467141 100644
> > > --- a/src/adapter.h
> > > +++ b/src/adapter.h
> > > @@ -26,6 +26,9 @@
> > >  #include <dbus/dbus.h>
> > >  #include <glib.h>
> > >
> > > +#include "lib/bluetooth.h"
> > > +#include "lib/sdp.h"
> > > +
> >
> > It might be better to have this included locally in a .c file needing them.
> >
> This fixes the complaint from the compiler where the symbols referred
> adapter.h was not found. This was revealed due to the circular
> dependency between adv_monitor and adapter where adv_monitor needs to
> include adapter.h for calling btd_adapter_get_index(), and adv_monitor
> doesn't have these two includes. In other words, adapter.h has been
> relying on other headers to include lib/sdp.h and lib/bluetooth.h
> which was not a good pattern in the first place. Besides, adapter.h
> does refer to symbols from lib/bluetooth.h and lib/sdp.h, so it makes
> sense to have them here.

Then let's have a separate patch and clean up the includes so we don't
have includes duplicates everywhere.

> > >  #define MAX_NAME_LENGTH                248
> > >
> > >  /* Invalid SSP passkey value used to indicate negative replies */
> > > diff --git a/src/adv_monitor.c b/src/adv_monitor.c
> > > new file mode 100644
> > > index 000000000..7044d3cca
> > > --- /dev/null
> > > +++ b/src/adv_monitor.c
> > > @@ -0,0 +1,149 @@
> > > +/*
> > > + *
> > > + *  BlueZ - Bluetooth protocol stack for Linux
> > > + *
> > > + *  Copyright (C) 2020 Google LLC
> > > + *
> > > + *
> > > + *  This program is free software; you can redistribute it and/or
> > > + *  modify it under the terms of the GNU Lesser General Public
> > > + *  License as published by the Free Software Foundation; either
> > > + *  version 2.1 of the License, or (at your option) any later version.
> > > + *
> > > + *  This program is distributed in the hope that it will be useful,
> > > + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > + *  Lesser General Public License for more details.
> > > + *
> > > + */
> > > +
> > > +#ifdef HAVE_CONFIG_H
> > > +#include <config.h>
> > > +#endif
> > > +
> > > +#define _GNU_SOURCE
> > > +#include <stdint.h>
> > > +
> > > +#include <glib.h>
> > > +#include <dbus/dbus.h>
> > > +#include <gdbus/gdbus.h>
> > > +
> > > +#include "adapter.h"
> > > +#include "dbus-common.h"
> > > +#include "log.h"
> > > +#include "src/shared/mgmt.h"
> > > +
> > > +#include "adv_monitor.h"
> > > +
> > > +#define ADV_MONITOR_MGR_INTERFACE      "org.bluez.AdvertisementMonitorManager1"
> > > +
> > > +struct btd_adv_monitor_manager {
> > > +       struct btd_adapter *adapter;
> > > +       struct mgmt *mgmt;
> > > +       uint16_t adapter_id;
> > > +       char *path;
> > > +};
> > > +
> > > +static const GDBusMethodTable adv_monitor_methods[] = {
> > > +       { GDBUS_METHOD("RegisterMonitor",
> > > +                                       GDBUS_ARGS({ "application", "o" }),
> > > +                                       NULL, NULL) },
> > > +       { GDBUS_ASYNC_METHOD("UnregisterMonitor",
> > > +                                       GDBUS_ARGS({ "application", "o" }),
> > > +                                       NULL, NULL) },
> > > +       { }
> > > +};
> > > +
> > > +static const GDBusPropertyTable adv_monitor_properties[] = {
> > > +       {"SupportedMonitorTypes", "as", NULL, NULL, NULL},
> > > +       {"SupportedFeatures", "as", NULL, NULL, NULL},
> > > +       { }
> > > +};
> > > +
> > > +/* Allocates a manager object */
> > > +static struct btd_adv_monitor_manager *manager_new(
> > > +                                               struct btd_adapter *adapter,
> > > +                                               struct mgmt *mgmt)
> > > +{
> > > +       struct btd_adv_monitor_manager *manager;
> > > +
> > > +       if (!adapter || !mgmt)
> > > +               return NULL;
> > > +
> > > +       manager = g_new0(struct btd_adv_monitor_manager, 1);
> >
> > Use new0.
> >
> > > +       if (!manager)
> > > +               return NULL;
> > > +
> > > +       manager->adapter = adapter;
> > > +       manager->mgmt = mgmt_ref(mgmt);
> > > +       manager->adapter_id = btd_adapter_get_index(adapter);
> > > +       manager->path = g_strdup(adapter_get_path(manager->adapter));
> >
> > If we are doing to reference the adapter we don't really need the
> > duplicate its path since we can just use adapter_get_path.
> As a part of adapter bring-down, the adv monitor manager would be
> destroyed too, and we should avoid accessing adapter's resource(s)
> during the bring-down to avoid incorrect values. By making a copy of
> the path, the code would be less error-prone since the adv monitor
> manager does not depend on the unknown state of the adapter.

Normally we do that by having the instance attached to the adapter, so
when the adapter needs to be freed it would cleanup all objects
depending on it so we can guarantee its resources are not released
ahead of time. Note that while we are not focusing too hard in
reducing the footprint of the stack I believe that is a good practice
in the long run, specially when that involve heap allocation.

> >
> > > +
> > > +       return manager;
> > > +}
> > > +
> > > +/* Frees a manager object */
> > > +static void manager_free(struct btd_adv_monitor_manager *manager)
> > > +{
> > > +       manager->adapter = NULL;
> >
> > No need to assign NULL if you are going to free the whole object at the end.
> Done.
> >
> > > +       mgmt_unref(manager->mgmt);
> > > +       manager->mgmt = NULL;
> >
> > Ditto.
> Done.
> >
> > > +       g_free(manager->path);
> > > +       manager->path = NULL;
> >
> > Ditto.
> Done.
> >
> > > +
> > > +       g_free(manager);
> > > +}
> > > +
> > > +/* Destroys a manager object and unregisters its D-Bus interface */
> > > +static void manager_destroy(struct btd_adv_monitor_manager *manager)
> > > +{
> > > +       if (!manager)
> > > +               return;
> > > +
> > > +       g_dbus_unregister_interface(btd_get_dbus_connection(),
> > > +                                       manager->path,
> > > +                                       ADV_MONITOR_MGR_INTERFACE);
> > > +
> > > +       manager_free(manager);
> > > +}
> > > +
> > > +/* Creates a manager and registers its D-Bus interface */
> > > +struct btd_adv_monitor_manager *btd_adv_monitor_manager_create(
> > > +                                               struct btd_adapter *adapter,
> > > +                                               struct mgmt *mgmt)
> > > +{
> > > +       struct btd_adv_monitor_manager *manager;
> > > +
> > > +       manager = manager_new(adapter, mgmt);
> > > +       if (!manager)
> > > +               return NULL;
> > > +
> > > +       if (g_dbus_register_interface(btd_get_dbus_connection(), manager->path,
> > > +                                       ADV_MONITOR_MGR_INTERFACE,
> > > +                                       adv_monitor_methods, NULL,
> > > +                                       adv_monitor_properties, manager, NULL)
> > > +               == FALSE) {
> >
> > We haven't been consistent with boolean checks but lately we start
> > using more the ! form instead of == FALSE.
> Done.
>
> Thanks,
> Miao
>
>
> >
> > > +               btd_error(manager->adapter_id,
> > > +                               "Failed to register "
> > > +                               ADV_MONITOR_MGR_INTERFACE);
> > > +               manager_free(manager);
> > > +               return NULL;
> > > +       }
> > > +
> > > +       btd_info(manager->adapter_id,
> > > +                       "Adv Monitor Manager created for adapter %s",
> > > +                       adapter_get_path(manager->adapter));
> > > +
> > > +       return manager;
> > > +}
> > > +
> > > +/* Destroys a manager and unregisters its D-Bus interface */
> > > +void btd_adv_monitor_manager_destroy(struct btd_adv_monitor_manager *manager)
> > > +{
> > > +       if (!manager)
> > > +               return;
> > > +
> > > +       btd_info(manager->adapter_id, "Destroy Adv Monitor Manager");
> > > +
> > > +       manager_destroy(manager);
> > > +}
> > > diff --git a/src/adv_monitor.h b/src/adv_monitor.h
> > > new file mode 100644
> > > index 000000000..69ea348f8
> > > --- /dev/null
> > > +++ b/src/adv_monitor.h
> > > @@ -0,0 +1,32 @@
> > > +/*
> > > + *
> > > + *  BlueZ - Bluetooth protocol stack for Linux
> > > + *
> > > + *  Copyright (C) 2020 Google LLC
> > > + *
> > > + *
> > > + *  This program is free software; you can redistribute it and/or
> > > + *  modify it under the terms of the GNU Lesser General Public
> > > + *  License as published by the Free Software Foundation; either
> > > + *  version 2.1 of the License, or (at your option) any later version.
> > > + *
> > > + *  This program is distributed in the hope that it will be useful,
> > > + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > + *  Lesser General Public License for more details.
> > > + *
> > > + */
> > > +
> > > +#ifndef __ADV_MONITOR_H
> > > +#define __ADV_MONITOR_H
> > > +
> > > +struct mgmt;
> > > +struct btd_adapter;
> > > +struct btd_adv_monitor_manager;
> > > +
> > > +struct btd_adv_monitor_manager *btd_adv_monitor_manager_create(
> > > +                                               struct btd_adapter *adapter,
> > > +                                               struct mgmt *mgmt);
> > > +void btd_adv_monitor_manager_destroy(struct btd_adv_monitor_manager *manager);
> > > +
> > > +#endif /* __ADV_MONITOR_H */
> > > --
> > > 2.26.2
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz


-- 
Luiz Augusto von Dentz