[PATCH v4] Bluetooth: Keep MSFT ext info throughout a hci_dev's life cycle

[Miao-chen Chou <mcchou@xxxxxxxxxxxx>]

This moves msft_do_close() from hci_dev_do_close() to
hci_unregister_dev() to avoid clearing MSFT extension info. This also
re-reads MSFT info upon every msft_do_open() even if MSFT extension has
been initialized.

The following test steps were performed.
(1) boot the test device and verify the MSFT support debug log in syslog
(2) restart bluetoothd and verify msft_do_close() doesn't get invoked
    and msft_do_open re-reads the MSFT support.

Signed-off-by: Miao-chen Chou <mcchou@xxxxxxxxxxxx>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
Reviewed-by: Archie Pusaka <apusaka@xxxxxxxxxxxx>
Reviewed-by: Alain Michaud <alainm@xxxxxxxxxxxx>
---

Changes in v4:
- Re-read the MSFT data instead of skipping if it's initiated already

Changes in v3:
- Remove the accepted commits from the series

 net/bluetooth/hci_core.c |  4 ++--
 net/bluetooth/msft.c     | 21 ++++++++++++++++++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index eeafed2efc0da..8056f0d4ae172 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1764,8 +1764,6 @@ int hci_dev_do_close(struct hci_dev *hdev)
 
 	hci_sock_dev_event(hdev, HCI_DEV_DOWN);
 
-	msft_do_close(hdev);
-
 	if (hdev->flush)
 		hdev->flush(hdev);
 
@@ -3844,6 +3842,8 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	unregister_pm_notifier(&hdev->suspend_notifier);
 	cancel_work_sync(&hdev->suspend_prepare);
 
+	msft_do_close(hdev);
+
 	hci_dev_do_close(hdev);
 
 	if (!test_bit(HCI_INIT, &hdev->flags) &&
diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c
index 8579bfeb28364..4465d018280eb 100644
--- a/net/bluetooth/msft.c
+++ b/net/bluetooth/msft.c
@@ -73,16 +73,31 @@ static bool read_supported_features(struct hci_dev *hdev,
 
 void msft_do_open(struct hci_dev *hdev)
 {
-	struct msft_data *msft;
+	struct msft_data *msft = NULL;
 
 	if (hdev->msft_opcode == HCI_OP_NOP)
 		return;
 
 	bt_dev_dbg(hdev, "Initialize MSFT extension");
 
-	msft = kzalloc(sizeof(*msft), GFP_KERNEL);
-	if (!msft)
+	/* If MSFT data exists, reset its members */
+	if (hdev->msft_data) {
+		msft = hdev->msft_data;
+		hdev->msft_data = NULL;
+
+		msft->features = 0;
+		kfree(msft->evt_prefix);
+		msft->evt_prefix = NULL;
+		msft->evt_prefix_len = 0;
+
+	} else {
+		msft = kzalloc(sizeof(*msft), GFP_KERNEL);
+	}
+
+	if (!msft) {
+		bt_dev_err(hdev, "Failed to init MSFT extension");
 		return;
+	}
 
 	if (!read_supported_features(hdev, msft)) {
 		kfree(msft);
-- 
2.30.0.280.ga3ce27912f-goog