linux-kernel - Re: [PATCH v2] Bluetooth: Shutdown controller after workqueues are flushed or cancelled

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Date:   Thu, 5 Aug 2021 23:50:09 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Mattijs Korpershoek <mkorpershoek@...libre.com>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Fabien Parent <fparent@...libre.com>,
        Sean Wang <sean.wang@...iatek.com>,
        "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: Shutdown controller after workqueues are
 flushed or cancelled

Hi Mattijs,

On Thu, Aug 5, 2021 at 2:55 PM Mattijs Korpershoek
<mkorpershoek@...libre.com> wrote:
>
> Hi Kai-Heng,
>
> Thanks for your patch,
>
> Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
>

[snipped]

> I confirm this diff works for me:
>
> root@...0-pumpkin:~# hciconfig hci0 up
> root@...0-pumpkin:~# hciconfig hci0 down
> root@...0-pumpkin:~# hciconfig hci0 up
> root@...0-pumpkin:~# hciconfig hci0
> hci0:   Type: Primary  Bus: SDIO
>         BD Address: 00:0C:E7:55:FF:12  ACL MTU: 1021:8  SCO MTU: 244:4
>         UP RUNNING
>         RX bytes:11268 acl:0 sco:0 events:829 errors:0
>         TX bytes:182569 acl:0 sco:0 commands:829 errors:0
>
> root@...0-pumpkin:~# hcitool scan
> Scanning ...
>         <redacted>       Pixel 3 XL
>
> Tested-by: Mattijs Korpershoek <mkorpershoek@...libre.com>

I found that btmtksdio_flush() only cancels the work instead of doing
flush_work(). That probably explains why putting ->shutdown right
before ->flush doesn't work.
So can you please test the following again:
diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index 9872ef18f9fea..b33c05ad2150b 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -649,9 +649,9 @@ static int btmtksdio_flush(struct hci_dev *hdev)
 {
        struct btmtksdio_dev *bdev = hci_get_drvdata(hdev);

-       skb_queue_purge(&bdev->txq);
+       flush_work(&bdev->tx_work);

-       cancel_work_sync(&bdev->tx_work);
+       skb_queue_purge(&bdev->txq);

        return 0;
 }
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 2560ed2f144d4..a61e610a400cb 100644

--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1785,6 +1785,14 @@ int hci_dev_do_close(struct hci_dev *hdev)
        aosp_do_close(hdev);
        msft_do_close(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 (hdev->flush)
                hdev->flush(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);

Kai-Heng