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

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Message-Id: <453AB6D8-9CA8-42B8-9807-5AC249E8618B@holtmann.org>
Date:   Mon, 16 Aug 2021 17:49:25 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.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>,
        "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 v2] Bluetooth: Move shutdown callback before flushing tx
 and rx queue

Hi Kai-Heng,

> 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(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel