Linux driver of vt6656 from staging area causes system to freeze.

Greg Kroah-Hartman gregkh at
Thu Feb 3 03:54:53 EST 2022

On Thu, Feb 03, 2022 at 01:41:11AM +0100, Philipp Hortmann wrote:
> I managed to get a device vt6656 (USB WiFi adapter). The device works OK
> when the computer is started and driver loaded. When the WLAN is disabled
> the system freezes often.
> I am using ubuntu 20.04 with kernel 5.17.0-rc1 x86_64
> branch: staging-testing
> After some tries I found out that it is a function in vnt_stop() main_usb.c
> with the following line that is causing this.
> usb_kill_urb(priv→interrupt_urb);
> But this memory is after this line still in use.

What "memory" do you mean?

> Digging deeper I found that the usb_submit_urb() function (in usbpipe.c
> vnt_start_interrupt_urb_complete) is called after the usb_kill_urb() is
> executed.
> So I tied the execution of the usb_submit_urb() to a flag called
> DEVICE_FLAGS_DISCONNECTED. After that no crashes were observed.
> So here my questions:
> - Is this the right place to fix?

Does it work for you?  If so, let's try it.

> - Do I need to log a bug report before a patch?

Not at all.  Please read the documention for how to submit a kernel
patch and we can take it from there.  The patch looks sane, now just
submit it correctly and we can review it and maybe apply it from there.


greg k-h

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