ath9k - Division by zero in kernel (as well as firmware panic)

[Nathan Royce]

ODroid XU4

$ uname -a
Linux computer 4.12.0-rc3-dirty #1 SMP Wed May 31 15:02:05 CDT 2017
armv7l GNU/Linux

$ lsusb
...
Bus 001 Device 002: ID 2109:2813 VIA Labs, Inc.
Bus 001 Device 010: ID 0cf3:7015 Qualcomm Atheros Communications
TP-Link TL-WN821N v3 / TL-WN822N v2 802.11n [Atheros AR7010+AR9287]
...

*****
Jun 02 16:20:11 computer hostapd[14954]: vwlan0: interface state
COUNTRY_UPDATE->HT_SCAN
Jun 02 16:20:17 computer hostapd[14954]: 20/40 MHz operation not
permitted on channel pri=7 sec=3 based on overlapping BSSes
Jun 02 16:20:18 computer kernel: Division by zero in kernel.
Jun 02 16:20:18 computer kernel: CPU: 1 PID: 14507 Comm: kworker/u16:2
Tainted: G        W       4.12.0-rc3-dirty #1
Jun 02 16:20:18 computer kernel: Hardware name: SAMSUNG EXYNOS
(Flattened Device Tree)
Jun 02 16:20:18 computer kernel: Workqueue: phy5 ieee80211_scan_work [mac80211]
Jun 02 16:20:18 computer kernel: [<c010ee0c>] (unwind_backtrace) from
[<c010b61c>] (show_stack+0x10/0x14)
Jun 02 16:20:18 computer kernel: [<c010b61c>] (show_stack) from
[<c0377708>] (dump_stack+0x88/0x9c)
Jun 02 16:20:18 computer kernel: [<c0377708>] (dump_stack) from
[<c03755d0>] (Ldiv0_64+0x8/0x18)
Jun 02 16:20:18 computer kernel: [<c03755d0>] (Ldiv0_64) from
[<bf71c9a4>] (ath9k_get_next_tbtt+0x58/0x5c [ath9k_common])
Jun 02 16:20:18 computer kernel: [<bf71c9a4>] (ath9k_get_next_tbtt
[ath9k_common]) from [<bf71cb90>] (ath9k_cmn_beacon_config
Jun 02 16:20:18 computer kernel: [<bf71cb90>]
(ath9k_cmn_beacon_config_ap [ath9k_common]) from [<bf7898c8>]
(ath9k_htc_beacon
Jun 02 16:20:18 computer kernel: [<bf7898c8>]
(ath9k_htc_beacon_config_ap [ath9k_htc]) from [<bf7885a8>]
(ath9k_htc_vif_recon
Jun 02 16:20:18 computer kernel: [<bf7885a8>] (ath9k_htc_vif_reconfig
[ath9k_htc]) from [<bf78860c>] (ath9k_htc_sw_scan_compl
Jun 02 16:20:18 computer kernel: [<bf78860c>]
(ath9k_htc_sw_scan_complete [ath9k_htc]) from [<bf506d38>]
(__ieee80211_scan_co
Jun 02 16:20:18 computer kernel: [<bf506d38>]
(__ieee80211_scan_completed [mac80211]) from [<bf507968>]
(ieee80211_scan_work+
Jun 02 16:20:18 computer kernel: [<bf507968>] (ieee80211_scan_work
[mac80211]) from [<c0133f10>] (process_one_work+0x1d8/0x40
Jun 02 16:20:18 computer kernel: [<c0133f10>] (process_one_work) from
[<c0134cb4>] (worker_thread+0x4c/0x564)
Jun 02 16:20:18 computer kernel: [<c0134cb4>] (worker_thread) from
[<c0139c20>] (kthread+0x14c/0x154)
Jun 02 16:20:18 computer kernel: [<c0139c20>] (kthread) from
[<c0107c38>] (ret_from_fork+0x14/0x3c)
Jun 02 16:20:18 computer hostapd[14954]: Using interface wlan0 with
hwaddr <sanitized> and ssid "<sanitized>"
Jun 02 16:20:18 computer kernel: IPv6: ADDRCONF(NETDEV_CHANGE):
vwlan0: link becomes ready
*****
This is a new one on me.

The "normal" problem (search shows to be a very old issue) I
consistently (daily or multiple times/day) encounter is:
*****
Jun 02 14:55:30 computer kernel: usb 1-1.1: ath: firmware panic!
exccause: 0x0000000d; pc: 0x0090ae81; badvaddr: 0x10ff4038.
Jun 02 14:55:30 computer kernel: usb 1-1.1: USB disconnect, device number 9
Jun 02 14:55:30 computer systemd-networkd[11959]: vwlan0: Lost carrier
Jun 02 14:55:30 computer kernel: br0: port 2(vwlan0) entered disabled state
Jun 02 14:55:30 computer kernel: wlan0: deauthenticating from
<sanitized> by local choice (Reason: 3=DEAUTH_LEAVING)
Jun 02 14:55:30 computer kernel: ath: phy4: Failed to wakeup in 500us
Jun 02 14:55:30 computer kernel: ath: phy4: Failed to wakeup in 500us
Jun 02 14:55:30 computer kernel: ath: phy4: Failed to wakeup in 500us
Jun 02 14:55:30 computer kernel: ath: phy4: Failed to wakeup in 500us
Jun 02 14:55:30 computer systemd-networkd[11959]: wlan0: Lost carrier
Jun 02 14:55:30 computer systemd[1]: Stopping A simple WPA encrypted
wireless connection using a static IP...
-- Subject: Unit netctl@xxxxxxxxxxxxx has begun shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit netctl@xxxxxxxxxxxxx has begun shutting down.
Jun 02 14:55:30 computer kernel: device vwlan0 left promiscuous mode
Jun 02 14:55:30 computer kernel: br0: port 2(vwlan0) entered disabled state
Jun 02 14:55:30 computer audit: ANOM_PROMISCUOUS dev=vwlan0 prom=0
old_prom=256 auid=4294967295 uid=0 gid=0 ses=4294967295
Jun 02 14:55:30 computer hostapd[13218]: vwlan0: AP-STA-DISCONNECTED <sanitized>
Jun 02 14:55:30 computer hostapd[13218]: Failed to set beacon parameters
Jun 02 14:55:30 computer hostapd[13218]: vwlan0: INTERFACE-DISABLED
Jun 02 14:55:30 computer kernel: usb 1-1.1: ath9k_htc: USB layer deinitialized
Jun 02 14:55:30 computer systemd[1]: Starting Load/Save RF Kill Switch Status...
-- Subject: Unit systemd-rfkill.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit systemd-rfkill.service has begun starting up.
Jun 02 14:55:30 computer systemd[1]: Started Load/Save RF Kill Switch Status.
-- Subject: Unit systemd-rfkill.service has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit systemd-rfkill.service has finished starting up.
--
-- The start-up result is done.
Jun 02 14:55:30 computer network[13261]: Stopping network profile 'wlan0'...
Jun 02 14:55:30 computer kernel: usb 1-1.1: new high-speed USB device
number 10 using exynos-ehci
Jun 02 14:55:30 computer kernel: usb 1-1.1: New USB device found,
idVendor=0cf3, idProduct=7015
Jun 02 14:55:30 computer kernel: usb 1-1.1: New USB device strings:
Mfr=16, Product=32, SerialNumber=48
Jun 02 14:55:30 computer kernel: usb 1-1.1: Product: USB WLAN
Jun 02 14:55:30 computer kernel: usb 1-1.1: Manufacturer: ATHEROS
Jun 02 14:55:30 computer kernel: usb 1-1.1: SerialNumber: 12345
Jun 02 14:55:30 computer kernel: usb 1-1.1: ath9k_htc: Firmware
ath9k_htc/htc_7010-1.4.0.fw requested
Jun 02 14:55:30 computer kernel: usb 1-1.1: ath9k_htc: Transferred FW:
ath9k_htc/htc_7010-1.4.0.fw, size: 72812
Jun 02 14:55:30 computer kernel: ath9k_htc 1-1.1:1.0: ath9k_htc: HTC
initialized with 45 credits
Jun 02 14:55:31 computer kernel: ath9k_htc 1-1.1:1.0: ath9k_htc: FW Version: 1.4
Jun 02 14:55:31 computer kernel: ath9k_htc 1-1.1:1.0: FW RMW support: On
Jun 02 14:55:31 computer kernel: ath: EEPROM regdomain: 0x809c
Jun 02 14:55:31 computer kernel: ath: EEPROM indicates we should
expect a country code
Jun 02 14:55:31 computer kernel: ath: doing EEPROM country->regdmn map search
Jun 02 14:55:31 computer kernel: ath: country maps to regdmn code: 0x52
Jun 02 14:55:31 computer kernel: ath: Country alpha2 being used: CN
Jun 02 14:55:31 computer kernel: ath: Regpair used: 0x52
Jun 02 14:55:31 computer kernel: ieee80211 phy5: Atheros AR9287 Rev:2
Jun 02 14:55:31 computer kernel: IPv6: ADDRCONF(NETDEV_UP): vwlan0:
link is not ready
Jun 02 14:55:31 computer hostapd[13218]: vwlan0: INTERFACE-ENABLED
Jun 02 14:55:31 computer network[13261]: Stopped network profile 'wlan0'
*****
I don't know the particular reason for this one.
At first it would happen every time I compiled anything (all cpu
used). Then I added the ZTE Mobley to the USB hub. Even after removing
the Mobley, the panic would still happen often.
I then recompiled the kernel so only the 4 LITTLE cpus were used
(big.LITTLE support+switcher), but the panic still happens sometimes.
Now the consistency seems to come from the wireless adapter used as
both AP and managed client.