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. Yegor -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
