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References: <20211202231123.v7.1.Ic0a40b84dee3825302890aaea690e73165c71820@changeid>
 <20211202231123.v7.2.I9eda306e4c542010535dc49b5488946af592795e@changeid>
In-Reply-To: <20211202231123.v7.2.I9eda306e4c542010535dc49b5488946af592795e@changeid>
From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Fri, 3 Dec 2021 14:18:56 -0800
Message-ID: <CABBYNZJPEhALUyevLAAP9Nhzda8M0emmsPwaXCcQWOSD+ytm5A@mail.gmail.com>
Subject: Re: [PATCH v7 2/2] bluetooth: Add MGMT Adv Monitor Device Found/Lost events
To:     Manish Mandlik <mmandlik@google.com>
Cc:     Marcel Holtmann <marcel@holtmann.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        ChromeOS Bluetooth Upstreaming 
        <chromeos-bluetooth-upstreaming@chromium.org>,
        Miao-chen Chou <mcchou@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Manish,

On Thu, Dec 2, 2021 at 11:16 PM Manish Mandlik <mmandlik@google.com> wrote:
>
> This patch introduces two new MGMT events for notifying the bluetoothd
> whenever the controller starts/stops monitoring a device.
>
> Test performed:
> - Verified by logs that the MSFT Monitor Device is received from the
>   controller and the bluetoothd is notified whenever the controller
>   starts/stops monitoring a device.
>
> Signed-off-by: Manish Mandlik <mmandlik@google.com>
> Reviewed-by: Miao-chen Chou <mcchou@google.com>
>
> ---
>
> Changes in v7:
> - Refactor mgmt_device_found() to fix stack frame size limit
>
> Changes in v6:
> - Fix compiler warning for mgmt_adv_monitor_device_found().
>
> Changes in v5:
> - New patch in the series. Split previous patch into two.
> - Update the Device Found logic to send existing Device Found event or
>   Adv Monitor Device Found event depending on the active scanning state.
>
>  include/net/bluetooth/hci_core.h |   3 +
>  include/net/bluetooth/mgmt.h     |  16 +++++
>  net/bluetooth/mgmt.c             | 106 +++++++++++++++++++++++++++++--
>  net/bluetooth/msft.c             |  15 ++++-
>  4 files changed, 134 insertions(+), 6 deletions(-)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 5ccd19dec77c..3b53214ff49f 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -599,6 +599,7 @@ struct hci_dev {
>         struct delayed_work     interleave_scan;
>
>         struct list_head        monitored_devices;
> +       bool                    advmon_pend_notify;
>
>  #if IS_ENABLED(CONFIG_BT_LEDS)
>         struct led_trigger      *power_led;
> @@ -1847,6 +1848,8 @@ void mgmt_adv_monitor_removed(struct hci_dev *hdev, u16 handle);
>  int mgmt_phy_configuration_changed(struct hci_dev *hdev, struct sock *skip);
>  int mgmt_add_adv_patterns_monitor_complete(struct hci_dev *hdev, u8 status);
>  int mgmt_remove_adv_monitor_complete(struct hci_dev *hdev, u8 status);
> +void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> +                                 bdaddr_t *bdaddr, u8 addr_type);
>
>  u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
>                       u16 to_multiplier);
> diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
> index 107b25deae68..99266f7aebdc 100644
> --- a/include/net/bluetooth/mgmt.h
> +++ b/include/net/bluetooth/mgmt.h
> @@ -1104,3 +1104,19 @@ struct mgmt_ev_controller_resume {
>  #define MGMT_WAKE_REASON_NON_BT_WAKE           0x0
>  #define MGMT_WAKE_REASON_UNEXPECTED            0x1
>  #define MGMT_WAKE_REASON_REMOTE_WAKE           0x2
> +
> +#define MGMT_EV_ADV_MONITOR_DEVICE_FOUND       0x002f
> +struct mgmt_ev_adv_monitor_device_found {
> +       __le16 monitor_handle;
> +       struct mgmt_addr_info addr;
> +       __s8   rssi;
> +       __le32 flags;
> +       __le16 eir_len;
> +       __u8   eir[0];
> +} __packed;
> +
> +#define MGMT_EV_ADV_MONITOR_DEVICE_LOST                0x0030
> +struct mgmt_ev_adv_monitor_device_lost {
> +       __le16 monitor_handle;
> +       struct mgmt_addr_info addr;
> +} __packed;
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index bf989ae03f9f..06e0769f350d 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -174,6 +174,8 @@ static const u16 mgmt_events[] = {
>         MGMT_EV_ADV_MONITOR_REMOVED,
>         MGMT_EV_CONTROLLER_SUSPEND,
>         MGMT_EV_CONTROLLER_RESUME,
> +       MGMT_EV_ADV_MONITOR_DEVICE_FOUND,
> +       MGMT_EV_ADV_MONITOR_DEVICE_LOST,
>  };
>
>  static const u16 mgmt_untrusted_commands[] = {
> @@ -9524,6 +9526,100 @@ static bool is_filter_match(struct hci_dev *hdev, s8 rssi, u8 *eir,
>         return true;
>  }
>
> +void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> +                                 bdaddr_t *bdaddr, u8 addr_type)
> +{
> +       struct mgmt_ev_adv_monitor_device_lost ev;
> +
> +       ev.monitor_handle = cpu_to_le16(handle);
> +       bacpy(&ev.addr.bdaddr, bdaddr);
> +       ev.addr.type = addr_type;
> +
> +       mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_LOST, hdev, &ev, sizeof(ev),
> +                  NULL);
> +}
> +
> +static void mgmt_adv_monitor_device_found(struct hci_dev *hdev,
> +                                         struct mgmt_ev_device_found *ev,
> +                                         size_t ev_size, bool discovering)
> +{
> +       char buf[518];

We should try to avoid declaring such big stack variable, instead Im
working on a set the should enable you to use skb_put/skb_put_data
directly into the skb, here are the current changes I have for
device_found:

https://gist.github.com/Vudentz/ffce584912eb7dc4add9c3bb25466fa5

I'm addressing Marcel's comments and will send the set to the list later today.

> +       struct mgmt_ev_adv_monitor_device_found *advmon_ev = (void *)buf;
> +       size_t advmon_ev_size;
> +       struct monitored_device *dev, *tmp;
> +       bool matched = false;
> +       bool notified = false;
> +
> +       /* We have received the Advertisement Report because:
> +        * 1. the kernel has initiated active discovery
> +        * 2. if not, we have pend_le_reports > 0 in which case we are doing
> +        *    passive scanning
> +        * 3. if none of the above is true, we have one or more active
> +        *    Advertisement Monitor
> +        *
> +        * For case 1 and 2, report all advertisements via MGMT_EV_DEVICE_FOUND
> +        * and report ONLY one advertisement per device for the matched Monitor
> +        * via MGMT_EV_ADV_MONITOR_DEVICE_FOUND event.
> +        *
> +        * For case 3, since we are not active scanning and all advertisements
> +        * received are due to a matched Advertisement Monitor, report all
> +        * advertisements ONLY via MGMT_EV_ADV_MONITOR_DEVICE_FOUND event.
> +        */
> +       if (discovering) {
> +               mgmt_event(MGMT_EV_DEVICE_FOUND, hdev, ev, ev_size, NULL);
> +
> +               if (!hdev->advmon_pend_notify)
> +                       return;
> +       }
> +
> +       /* Make sure that the buffer is big enough */
> +       advmon_ev_size = ev_size + (sizeof(*advmon_ev) - sizeof(*ev));
> +       if (advmon_ev_size > sizeof(buf))
> +               return;
> +
> +       /* ADV_MONITOR_DEVICE_FOUND is similar to DEVICE_FOUND event except
> +        * that it also has 'monitor_handle'. Make a copy of DEVICE_FOUND and
> +        * store monitor_handle of the matched monitor.
> +        */
> +       memcpy(&advmon_ev->addr, ev, ev_size);
> +
> +       hdev->advmon_pend_notify = false;
> +
> +       list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices, list) {
> +               if (!bacmp(&dev->bdaddr, &advmon_ev->addr.bdaddr)) {
> +                       matched = true;
> +
> +                       if (!dev->notified) {
> +                               advmon_ev->monitor_handle =
> +                                               cpu_to_le16(dev->handle);
> +
> +                               mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_FOUND,
> +                                          hdev, advmon_ev, advmon_ev_size,
> +                                          NULL);
> +
> +                               notified = true;
> +                               dev->notified = true;
> +                       }
> +               }
> +
> +               if (!dev->notified)
> +                       hdev->advmon_pend_notify = true;
> +       }
> +
> +       if (!discovering &&
> +           ((matched && !notified) || !msft_monitor_supported(hdev))) {
> +               /* Handle 0 indicates that we are not active scanning and this
> +                * is a subsequent advertisement report for an already matched
> +                * Advertisement Monitor or the controller offloading support
> +                * is not available.
> +                */
> +               advmon_ev->monitor_handle = 0;
> +
> +               mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_FOUND, hdev, advmon_ev,
> +                          advmon_ev_size, NULL);
> +       }
> +}
> +
>  void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
>                        u8 addr_type, u8 *dev_class, s8 rssi, u32 flags,
>                        u8 *eir, u16 eir_len, u8 *scan_rsp, u8 scan_rsp_len)
> @@ -9531,6 +9627,7 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
>         char buf[512];
>         struct mgmt_ev_device_found *ev = (void *)buf;
>         size_t ev_size;
> +       bool report_device_found = hci_discovery_active(hdev);
>
>         /* Don't send events for a non-kernel initiated discovery. With
>          * LE one exception is if we have pend_le_reports > 0 in which
> @@ -9539,11 +9636,10 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
>         if (!hci_discovery_active(hdev)) {
>                 if (link_type == ACL_LINK)
>                         return;
> -               if (link_type == LE_LINK &&
> -                   list_empty(&hdev->pend_le_reports) &&
> -                   !hci_is_adv_monitoring(hdev)) {
> +               if (link_type == LE_LINK && !list_empty(&hdev->pend_le_reports))
> +                       report_device_found = true;
> +               else if (!hci_is_adv_monitoring(hdev))
>                         return;
> -               }
>         }
>
>         if (hdev->discovery.result_filtering) {
> @@ -9606,7 +9702,7 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
>         ev->eir_len = cpu_to_le16(eir_len + scan_rsp_len);
>         ev_size = sizeof(*ev) + eir_len + scan_rsp_len;
>
> -       mgmt_event(MGMT_EV_DEVICE_FOUND, hdev, ev, ev_size, NULL);
> +       mgmt_adv_monitor_device_found(hdev, ev, ev_size, report_device_found);
>  }
>
>  void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c
> index aadabe78baf6..3e2385562d2b 100644
> --- a/net/bluetooth/msft.c
> +++ b/net/bluetooth/msft.c
> @@ -579,8 +579,16 @@ void msft_do_close(struct hci_dev *hdev)
>
>         hci_dev_lock(hdev);
>
> -       /* Clear any devices that are being monitored */
> +       /* Clear any devices that are being monitored and notify device lost */
> +
> +       hdev->advmon_pend_notify = false;
> +
>         list_for_each_entry_safe(dev, tmp_dev, &hdev->monitored_devices, list) {
> +               if (dev->notified)
> +                       mgmt_adv_monitor_device_lost(hdev, dev->handle,
> +                                                    &dev->bdaddr,
> +                                                    dev->addr_type);
> +
>                 list_del(&dev->list);
>                 kfree(dev);
>         }
> @@ -639,6 +647,7 @@ static void msft_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr,
>
>         INIT_LIST_HEAD(&dev->list);
>         list_add(&dev->list, &hdev->monitored_devices);
> +       hdev->advmon_pend_notify = true;
>  }
>
>  /* This function requires the caller holds hdev->lock */
> @@ -649,6 +658,10 @@ static void msft_device_lost(struct hci_dev *hdev, bdaddr_t *bdaddr,
>
>         list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices, list) {
>                 if (dev->handle == mgmt_handle) {
> +                       if (dev->notified)
> +                               mgmt_adv_monitor_device_lost(hdev, mgmt_handle,
> +                                                            bdaddr, addr_type);
> +
>                         list_del(&dev->list);
>                         kfree(dev);
>
> --
> 2.34.0.384.gca35af8252-goog
>


-- 
Luiz Augusto von Dentz