Subject: Re: [PATCH v2] Bluetooth: Move shutdown callback before flushing tx and rx queue

From: Mattijs Korpershoek <[email-masked]>
Date: Wed, 11 Aug 2021 10:25:09 +0200

Hi Kai-Heng,

Thank you for your patch.

Kai-Heng Feng <[email-masked]> writes:

> 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 <[email-masked]>
> Tested-by: Hsin-Yi Wang <[email-masked]>
> Cc: Guenter Roeck <[email-masked]>
> Fixes: 0ea9fd001a14 ("Bluetooth: Shutdown controller after workqueues are flushed or cancelled")
> Signed-off-by: Kai-Heng Feng <[email-masked]>
> ---
> 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);
I confirm this works fine on mt8183-pumpkin using the btmtksdio driver.

Tested-by: Mattijs Korpershoek <[email-masked]>
> -- 
> 2.31.1