linux-kernel - [PATCH v2] Bluetooth: Move shutdown callback before flushing tx and rx queue

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Message-Id: <20210810045315.184383-1-kai.heng.feng@canonical.com>
Date:   Tue, 10 Aug 2021 12:53:15 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     marcel@...tmann.org, johan.hedberg@...il.com, luiz.dentz@...il.com
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Mattijs Korpershoek <mkorpershoek@...libre.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-bluetooth@...r.kernel.org (open list:BLUETOOTH SUBSYSTEM),
        netdev@...r.kernel.org (open list:NETWORKING [GENERAL]),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2] Bluetooth: Move shutdown callback before flushing tx and rx queue

Commit 0ea9fd001a14 ("Bluetooth: Shutdown controller after workqueues
are flushed or cancelled") introduced a regression that makes mtkbtsdio
driver stops working:
[   36.593956] Bluetooth: hci0: Firmware already downloaded
[   46.814613] Bluetooth: hci0: Execution of wmt command timed out
[   46.814619] Bluetooth: hci0: Failed to send wmt func ctrl (-110)

The shutdown callback depends on the result of hdev->rx_work, so we
should call it before flushing rx_work:
-> btmtksdio_shutdown()
 -> mtk_hci_wmt_sync()
  -> __hci_cmd_send()
   -> wait for BTMTKSDIO_TX_WAIT_VND_EVT gets cleared

-> btmtksdio_recv_event()
 -> hci_recv_frame()
  -> queue_work(hdev->workqueue, &hdev->rx_work)
   -> clears BTMTKSDIO_TX_WAIT_VND_EVT

So move the shutdown callback before flushing TX/RX queue to resolve the
issue.

Reported-and-tested-by: Mattijs Korpershoek <mkorpershoek@...libre.com>
Tested-by: Hsin-Yi Wang <hsinyi@...omium.org>
Cc: Guenter Roeck <linux@...ck-us.net>
Fixes: 0ea9fd001a14 ("Bluetooth: Shutdown controller after workqueues are flushed or cancelled")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v2: 
 Move the shutdown callback before clearing HCI_UP, otherwise 1)
 shutdown callback won't be called and 2) other routines that depend on
 HCI_UP won't work.

 net/bluetooth/hci_core.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index cb2e9e513907..8622da2d9395 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1727,6 +1727,14 @@ int hci_dev_do_close(struct hci_dev *hdev)
 	hci_request_cancel_all(hdev);
 	hci_req_sync_lock(hdev);
 
+	if (!hci_dev_test_flag(hdev, HCI_UNREGISTER) &&
+	    !hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
+	    test_bit(HCI_UP, &hdev->flags)) {
+		/* Execute vendor specific shutdown routine */
+		if (hdev->shutdown)
+			hdev->shutdown(hdev);
+	}
+
 	if (!test_and_clear_bit(HCI_UP, &hdev->flags)) {
 		cancel_delayed_work_sync(&hdev->cmd_timer);
 		hci_req_sync_unlock(hdev);
@@ -1798,14 +1806,6 @@ int hci_dev_do_close(struct hci_dev *hdev)
 		clear_bit(HCI_INIT, &hdev->flags);
 	}
 
-	if (!hci_dev_test_flag(hdev, HCI_UNREGISTER) &&
-	    !hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
-	    test_bit(HCI_UP, &hdev->flags)) {
-		/* Execute vendor specific shutdown routine */
-		if (hdev->shutdown)
-			hdev->shutdown(hdev);
-	}
-
 	/* flush cmd  work */
 	flush_work(&hdev->cmd_work);
 
-- 
2.31.1