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

On Tue, Aug 10, 2021 at 12:10 PM Hsin-Yi Wang [off-list ref] wrote:

On Tue, Aug 10, 2021 at 1:44 AM Kai-Heng Feng
[off-list ref] wrote:

quoted

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 <redacted>
Tested-by: Hsin-Yi Wang <redacted>

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.

Ah, sorry for causing your trouble, I am the one who got confused :(
HCI_UP is obviously required for hci_req_sync() to work.

Let me resend one, and sorry again!

Kai-Heng

quoted

Cc: Guenter Roeck <linux@roeck-us.net>
Fixes: 0ea9fd001a14 ("Bluetooth: Shutdown controller after workqueues are flushed or cancelled")
Signed-off-by: Kai-Heng Feng <redacted>
---
 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