Issues with latest kernel versions and Monitor mode

[Michal Kazior]

On 25 April 2016 at 18:19, Amato Carbonara <acarbonara13 at gmail.com> wrote:
> Hello,
>   I recently updated the Linux kernel to latest stable release (4.5.1
> and 4.5.2) and long term support releases (4.4.7 and 4.4.8).  With the
> aforementioned kernel releases, the QCA988x chip was unable to be
> placed in monitor mode.
>
> More information:
>
> OS = Ubuntu 14.04 LTS
> WiFi chip = QCA988x
> Firmware = ath10k
> Version = 10.2.4.70.37-2
>
> Commands used to enter WiFi adapter into monitor mode:
> ifconfig wlan1 down
> iw dev wlan1 set type monitor
> ifconfig wlan1 up
>
> After entering the last command (ifconfig wlan1 up), the following
> error is displayed:
> SIOCSIFFLAGS: Cannot send after transport endpoint shutdown
>
> No error is displayed when using kernel version 4.3.3
> I noticed the problem when I upgraded to 4.4.7 and 4.5.1

FWIW Both 4.5.y and 4.4.y don't have a fix for monitor crashes[1].

[1]: https://patchwork.kernel.org/patch/8481281/

I'm guessing the other don't have it as well. It'd be helpful if you
could post kernel log as I suspect there's a FW crash dump there. To
make things really certain I'd suggest to load ath10k_core with
debug_mask=0xffffff3f and post the kernel log to pastebin to confirm.


Michał