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

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Date:   Tue, 10 Aug 2021 12:10:26 +0800
From:   Hsin-Yi Wang <hsinyi@...omium.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Mattijs Korpershoek <mkorpershoek@...libre.com>,
        Guenter Roeck <linux@...ck-us.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "open list:BLUETOOTH SUBSYSTEM" <linux-bluetooth@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Bluetooth: Move shutdown callback before flushing tx and
 rx queue

On Tue, Aug 10, 2021 at 1:44 AM Kai-Heng Feng
<kai.heng.feng@...onical.com> wrote:
>
> 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>

Hello,

Sorry for confusion, but the version I tested is this one:
https://lkml.org/lkml/2021/8/4/486 (shutdown is prior to the
test_and_clear HCI_UP)
I tested this version and still see the error I've seen before.




> 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>
> ---
>  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..8da04c899197 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1735,6 +1735,14 @@ int hci_dev_do_close(struct hci_dev *hdev)
>
>         hci_leds_update_powered(hdev, false);
>
> +       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 RX and TX works */
>         flush_work(&hdev->tx_work);
>         flush_work(&hdev->rx_work);
> @@ -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
>