Re: [PATCH v7 2/2] bluetooth: Add MGMT Adv Monitor Device Found/Lost events

Hi Manish,

On Mon, Dec 6, 2021 at 8:39 AM Manish Mandlik [off-list ref] wrote:

Hi Luiz,

On Fri, Dec 3, 2021 at 5:19 PM Luiz Augusto von Dentz [off-list ref] wrote:

quoted

Hi Manish,

On Thu, Dec 2, 2021 at 11:16 PM Manish Mandlik [off-list ref] wrote:

quoted

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 <redacted>
Reviewed-by: Miao-chen Chou <redacted>

---

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.

Please let me know once these changes land bluetooth-next, I'll update my patch and send out the new revision.

Those changes are already in bluetooth-next.

quoted

quoted

+       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

Thanks,
Manish.

-- 
Luiz Augusto von Dentz