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Date:   Wed,  3 Aug 2022 13:24:50 -0700
Message-Id: <20220803132319.1.I5acde3b5af78dbd2ea078d5eb4158d23b496ac87@changeid>
Mime-Version: 1.0
Subject: [PATCH 1/2] Bluetooth: Disable AdvMonitor SamplingPeriod while active scan
From:   Manish Mandlik <mmandlik@google.com>
To:     marcel@holtmann.org, luiz.dentz@gmail.com
Cc:     chromeos-bluetooth-upstreaming@chromium.org,
        linux-bluetooth@vger.kernel.org,
        Manish Mandlik <mmandlik@google.com>,
        Miao-chen Chou <mcchou@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Some controllers apply Sampling Period even while active scanning.
So, to keep the behavior consistent across all controllers, don't
use Sampling Period during active scanning to force the controller
to report all advertisements even if it matches the monitor.

Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Miao-chen Chou <mcchou@google.com>
---

 net/bluetooth/hci_sync.c |  6 ++++++
 net/bluetooth/msft.c     | 45 +++++++++++++++++++++++++++++++++++++---
 net/bluetooth/msft.h     |  2 ++
 3 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index e6d804b82b67..cb0c219ebe1c 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -4649,6 +4649,9 @@ int hci_stop_discovery_sync(struct hci_dev *hdev)
 	if (use_ll_privacy(hdev))
 		hci_resume_advertising_sync(hdev);
 
+	/* Sampling Period is disabled while active scanning, re-enable it */
+	msft_set_active_scan(hdev, false);
+
 	/* No further actions needed for LE-only discovery */
 	if (d->type == DISCOV_TYPE_LE)
 		return 0;
@@ -5139,6 +5142,9 @@ int hci_start_discovery_sync(struct hci_dev *hdev)
 	if (err)
 		return err;
 
+	/* Disable Sampling Period while active scanning */
+	msft_set_active_scan(hdev, true);
+
 	bt_dev_dbg(hdev, "timeout %u ms", jiffies_to_msecs(timeout));
 
 	/* When service discovery is used and the controller has a
diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c
index bee6a4c656be..f63c911b210c 100644
--- a/net/bluetooth/msft.c
+++ b/net/bluetooth/msft.c
@@ -101,6 +101,7 @@ struct msft_data {
 	struct list_head handle_map;
 	__u8 resuming;
 	__u8 suspending;
+	__u8 active_scan;
 	__u8 filter_enabled;
 };
 
@@ -333,14 +334,14 @@ static int msft_remove_monitor_sync(struct hci_dev *hdev,
 }
 
 /* This function requires the caller holds hci_req_sync_lock */
-int msft_suspend_sync(struct hci_dev *hdev)
+static void remove_all_monitors(struct hci_dev *hdev)
 {
 	struct msft_data *msft = hdev->msft_data;
 	struct adv_monitor *monitor;
 	int handle = 0;
 
 	if (!msft || !msft_monitor_supported(hdev))
-		return 0;
+		return;
 
 	msft->suspending = true;
 
@@ -356,6 +357,12 @@ int msft_suspend_sync(struct hci_dev *hdev)
 
 	/* All monitors have been removed */
 	msft->suspending = false;
+}
+
+/* This function requires the caller holds hci_req_sync_lock */
+int msft_suspend_sync(struct hci_dev *hdev)
+{
+	remove_all_monitors(hdev);
 
 	return 0;
 }
@@ -392,6 +399,7 @@ static bool msft_monitor_pattern_valid(struct adv_monitor *monitor)
 static int msft_add_monitor_sync(struct hci_dev *hdev,
 				 struct adv_monitor *monitor)
 {
+	struct msft_data *msft = hdev->msft_data;
 	struct msft_cp_le_monitor_advertisement *cp;
 	struct msft_le_monitor_advertisement_pattern_data *pattern_data;
 	struct msft_le_monitor_advertisement_pattern *pattern;
@@ -417,7 +425,16 @@ static int msft_add_monitor_sync(struct hci_dev *hdev,
 	cp->rssi_high = monitor->rssi.high_threshold;
 	cp->rssi_low = monitor->rssi.low_threshold;
 	cp->rssi_low_interval = (u8)monitor->rssi.low_threshold_timeout;
-	cp->rssi_sampling_period = monitor->rssi.sampling_period;
+
+	/* Some controllers apply Sampling Period even while active scanning.
+	 * So, to keep the behavior consistent across all controllers, don't
+	 * use Sampling Period during active scanning to force the controller
+	 * to report all advertisements even if it matches the monitor.
+	 */
+	if (msft->active_scan)
+		cp->rssi_sampling_period = 0;
+	else
+		cp->rssi_sampling_period = monitor->rssi.sampling_period;
 
 	cp->cond_type = MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN;
 
@@ -815,6 +832,28 @@ void msft_req_add_set_filter_enable(struct hci_request *req, bool enable)
 	hci_req_add(req, hdev->msft_opcode, sizeof(cp), &cp);
 }
 
+/* This function requires the caller holds hci_req_sync_lock */
+void msft_set_active_scan(struct hci_dev *hdev, bool enable)
+{
+	struct msft_data *msft = hdev->msft_data;
+
+	if (!msft)
+		return;
+
+	/* Remove all monitors */
+	remove_all_monitors(hdev);
+
+	/* Clear all tracked devices */
+	hci_dev_lock(hdev);
+	hdev->advmon_pend_notify = false;
+	msft_monitor_device_del(hdev, 0, NULL, 0, true);
+	hci_dev_unlock(hdev);
+
+	/* Update active scan and reregister all monitors */
+	msft->active_scan = enable;
+	reregister_monitor(hdev);
+}
+
 int msft_set_filter_enable(struct hci_dev *hdev, bool enable)
 {
 	struct hci_request req;
diff --git a/net/bluetooth/msft.h b/net/bluetooth/msft.h
index 2a63205b377b..7dfd866dacc4 100644
--- a/net/bluetooth/msft.h
+++ b/net/bluetooth/msft.h
@@ -22,6 +22,7 @@ __u64 msft_get_features(struct hci_dev *hdev);
 int msft_add_monitor_pattern(struct hci_dev *hdev, struct adv_monitor *monitor);
 int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor);
 void msft_req_add_set_filter_enable(struct hci_request *req, bool enable);
+void msft_set_active_scan(struct hci_dev *hdev, bool enable);
 int msft_set_filter_enable(struct hci_dev *hdev, bool enable);
 int msft_suspend_sync(struct hci_dev *hdev);
 int msft_resume_sync(struct hci_dev *hdev);
@@ -55,6 +56,7 @@ static inline int msft_remove_monitor(struct hci_dev *hdev,
 
 static inline void msft_req_add_set_filter_enable(struct hci_request *req,
 						  bool enable) {}
+static inline void msft_set_active_scan(struct hci_dev *hdev, bool enable) {}
 static inline int msft_set_filter_enable(struct hci_dev *hdev, bool enable)
 {
 	return -EOPNOTSUPP;
-- 
2.37.1.455.g008518b4e5-goog