Re: [PATCH] bluetooth: Don't initialize msft/aosp when using user channel

A race condition is triggered when usermode control is given to
userspace before the kernel's MSFT query responds, resulting in an
unexpected response to userspace's reset command.

Issue can be observed in btmon:
< HCI Command: Vendor (0x3f|0x001e) plen 2                    #3 [hci0]
        05 01                                            ..
@ USER Open: bt_stack_manage (privileged) version 2.22  {0x0002} [hci0]
< HCI Command: Reset (0x03|0x0003) plen 0                     #4 [hci0]

quoted

HCI Event: Command Complete (0x0e) plen 5                   #5 [hci0]

      Vendor (0x3f|0x001e) ncmd 1
        Status: Command Disallowed (0x0c)
        05                                               .

quoted

HCI Event: Command Complete (0x0e) plen 4                   #6 [hci0]

      Reset (0x03|0x0003) ncmd 2
        Status: Success (0x00)

Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Sonny Sasaka <redacted>
Signed-off-by: Jesse Melhuish <redacted>
---

 net/bluetooth/hci_core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c07b2d2a44b0..2b5df597e7ed 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c

@@ -1595,8 +1595,10 @@ static int hci_dev_do_open(struct hci_dev *hdev)
            hci_dev_test_flag(hdev, HCI_VENDOR_DIAG) && hdev->set_diag)
                ret = hdev->set_diag(hdev, true);

-       msft_do_open(hdev);
-       aosp_do_open(hdev);
+       if (!hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
+               msft_do_open(hdev);
+               aosp_do_open(hdev);
+       }