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    Subject[PATCH 4.19 084/293] Bluetooth: Move shutdown callback before flushing tx and rx queue
    Date
    From: Kai-Heng Feng <kai.heng.feng@canonical.com>

    [ Upstream commit 0ea53674d07fb6db2dd7a7ec2fdc85a12eb246c2 ]

    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@baylibre.com>
    Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
    Cc: Guenter Roeck <linux@roeck-us.net>
    Fixes: 0ea9fd001a14 ("Bluetooth: Shutdown controller after workqueues are flushed or cancelled")
    Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/bluetooth/hci_core.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
    index 7a85f215da45..ec6150564f59 100644
    --- a/net/bluetooth/hci_core.c
    +++ b/net/bluetooth/hci_core.c
    @@ -1622,6 +1622,14 @@ 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);
    --
    2.30.2


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