Yegor Yefremov wrote:
> Hi Craig,
>
> On Tue, May 10, 2016 at 8:08 AM, Craig McQueen
> <[email protected]> wrote:
> > I previously wrote:
> >> I previously wrote:
> >> > I previously wrote:
> >> > >
> >> > > I have a D-Link DWA-140 USB Wi-Fi device which is rt2800 based
> >> > > (5392 chipset). I've been testing it on a BeagleBone Black
> >> > > running an Ubuntu
> >> > > 16.04 image (4.4.6 kernel), with a USB hub.
> >> > >
> >> > > When I unplug the Wi-Fi device from the USB hub, and it's
> >> > > connected to an access point, and then I unplug it, the OS appears to
> lock up.
> >> > > I get messages about a soft lockup on the serial console:
> >> > >
> >> > > [ 9736.136702] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s!
> >> > > [kworker/u2:0:1129] [ 9764.136701] NMI watchdog: BUG: soft lockup
> >> > > -
> >> > > CPU#0 stuck for 22s! [kworker/u2:0:1129] [ 9792.136701] NMI
> watchdog:
> >> > > BUG: soft lockup - CPU#0 stuck for 22s! [kworker/u2:0:1129] [
> >> > > 9820.136699] NMI
> >> > > watchdog: BUG: soft lockup - CPU#0 stuck for 22s!
> >> > > [kworker/u2:0:1129] [ 9848.136696] NMI watchdog: BUG: soft lockup
> >> > > -
> >> CPU#0 stuck for 22s!
> >> > > [kworker/u2:0:1129]
> >> > >
> >> > > This will repeat indefinitely, until I unplug the hub, which
> >> > > resolves the soft lockup and then the system seems to function
> normally.
> >> > >
> >> > > I've attached a dmesg log of the soft lockup stack traces. They
> >> > > seem to indicate a lockup in workqueue rt2x00usb_work_rxdone()
> >> > > (specifically in
> >> > > usb_hcd_submit_urb() called from rt2x00usb_kick_rx_entry() called
> >> > > from rt2x00usb_clear_entry()).
> >> > >
> >> > > I originally found this bug on a 3.14.x kernel built with Yocto
> >> > > for a BeagleBone Black-based product. So it seems this is a bug
> >> > > that has been around for some time.
> >> >
> >> > I should also note that on the 3.14.x Yocto-built kernel on
> >> > BeagleBone Black, this bug does not occur if the rt2800 device is
> >> > unplugged directly from the BBB's USB port. It only occurs if unplugged
> from a hub.
> >> >
> >> > I have tested this on an i586 based eBox-3310A mini-PC running
> >> > Debian 8.4, which has a 3.16.0 kernel, with the same hub and same
> >> > rt2800 device. But I was not able to reproduce this issue.
> >>
> >> There is a patch for the AM335x musb driver that seems to fix this:
> >>
> >> http://marc.info/?l=linux-usb&m=146173995117456&w=2
> >>
> >> So it seems that this issue's root cause is in the AM335x USB
> >> interrupt handling, and not the Wi-Fi rt2800 driver.
> >
> > Having applied two AM335x USB patches in the 3.14.49 kernel, that does
> seem to resolve the soft lock-up on the RX side. The two patches are:
> >
> > http://marc.info/?l=linux-usb&m=146173995117456&w=2
> > http://marc.info/?l=linux-usb&m=146222355213935&w=2
> >
> > But I am finding there is still a lock-up issue when unplugging from a hub,
> this time on the TX side. It is more likely if there is Wi-Fi traffic in
> progress
> when the unplug occurs. I'm attaching a log. Essentially there are a heap of
> lines (100 or so per second):
> >
> > [ 1866.693511] ieee80211 phy7: rt2800usb_tx_sta_fifo_read_completed:
> > Warning - TX status read failed -71
> >
> > Which finally stop shortly after USB disconnect is detected:
> >
> > [ 1866.985854] usb 1-1.3: USB disconnect, device number 10
> >
> > However that disconnect message is typically 30-90 seconds after the
> unplug happened. It seems that the USB disconnect detection is delayed due
> to the CPU load of the TX.
> >
> > I also sometimes see a kernel panic. That can occur whether connected to a
> USB hub or directly to the on-board USB port. See the attached log.
> >
> > I'm not so familiar with either the Wi-Fi or USB stacks in the Linux
> > kernel, so I would appreciate any advice with debugging and fixing
> > this. (My previous investigations indicate these issues are present in
> > both 3.14.x kernel and 4.4.6 kernel. I'm more familiar with working
> > with the 3.14.x kernel under Yocto, but I could try moving to 4.4.6
> > kernel for Ubuntu. I'm open to advice on which to investigate on.)
>
> Take a look at this patch: http://marc.info/?l=linux-
> usb&m=146222355213935&w=2
>
> If it fixes your issue please provide your "tested-by" tag here.
Hi Yegor,
I am using that patch, and I referred to it in my last message. But it doesn't
fix this issue.
Thanks,
Craig McQueen
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