Bug 215713

Summary:	New (useless?) warning messages from BlueTooth in kernel 5.17
Product:	Drivers	Reporter:	Artem S. Tashkinov (aros)
Component:	Bluetooth	Assignee:	linux-bluetooth (linux-bluetooth)
Status:	RESOLVED CODE_FIX
Severity:	low	CC:	luiz.dentz
Priority:	P1
Hardware:	x86-64
OS:	Linux
Kernel Version:	5.17	Subsystem:
Regression:	Yes	Bisected commit-id:

Description Artem S. Tashkinov 2022-03-21 12:55:16 UTC

I've just upgraded from 5.15.30 to 5.17 and now upon pairing my BT headphones I see brand new warning messages I've never seen before:

Bluetooth: hci0: unexpected event 0xff length: 25 > 0
Bluetooth: hci0: unexpected event 0xff length: 4 > 0

I wonder if it's a kernel bug or it's a valid message. 

The BT headphones work without any issues though.

The device is 8087:0025 Intel Corp. Wireless-AC 9260 Bluetooth Adapter.

# lsmod | grep bt
btusb                  40960  0
btbcm                  20480  1 btusb
btintel                32768  1 btusb
bluetooth             471040  52 btintel,btbcm,bnep,btusb,rfcomm

# dmesg -t | egrep -i "bt|blue" 
Bluetooth: Core ver 2.22
NET: Registered PF_BLUETOOTH protocol family
Bluetooth: HCI device and connection manager initialized
Bluetooth: HCI socket layer initialized
Bluetooth: L2CAP socket layer initialized
Bluetooth: SCO socket layer initialized
usbcore: registered new interface driver btusb
Bluetooth: hci0: Found device firmware: intel/ibt-18-16-1.sfi
Bluetooth: hci0: Boot Address: 0x40800
Bluetooth: hci0: Firmware Version: 86-46.21
Bluetooth: hci0: Firmware already loaded
Bluetooth: BNEP (Ethernet Emulation) ver 1.3
Bluetooth: BNEP socket layer initialized
Bluetooth: RFCOMM TTY layer initialized
Bluetooth: RFCOMM socket layer initialized
Bluetooth: RFCOMM ver 1.11
Bluetooth: hci0: unexpected event 0xff length: 25 > 0
Bluetooth: hci0: unexpected event 0xff length: 4 > 0

Comment 1 Luiz Von Dentz 2022-03-22 00:35:49 UTC

https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/net/bluetooth/hci_event.c?id=314d8cd2787418c5ac6b02035c344644f47b292b

It haven't made to 5.17 though but it is already fixed in bluetooth-next.

Comment 2 Artem S. Tashkinov 2022-03-22 18:15:12 UTC

(In reply to Luiz Von Dentz from comment #1)
> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/
> commit/net/bluetooth/hci_event.c?id=314d8cd2787418c5ac6b02035c344644f47b292b
> 
> It haven't made to 5.17 though but it is already fixed in bluetooth-next.

I'm not sure what to make of this patch (don't quite understand the code - error logging looks to be the same regardless albeit it's rate limited) - I hope to see it applied to future stable releases.

Comment 3 Luiz Von Dentz 2022-03-22 19:51:35 UTC

(In reply to Artem S. Tashkinov from comment #2)
> (In reply to Luiz Von Dentz from comment #1)
> >
> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/
> >
> commit/net/bluetooth/hci_event.c?id=314d8cd2787418c5ac6b02035c344644f47b292b
> > 
> > It haven't made to 5.17 though but it is already fixed in bluetooth-next.
> 
> I'm not sure what to make of this patch (don't quite understand the code -
> error logging looks to be the same regardless albeit it's rate limited) - I
> hope to see it applied to future stable releases.

It does switch to HCI_EV_VENDOR (0xff) to be variable size so it won't be triggering the error, the rate limite is just a safeguard in case some other event start spamming.