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Linus Lüssing 12c8f3d1cd ath9k: fix data bus crash when setting nf_override via debugfs
When trying to set the noise floor via debugfs, a "data bus error"
crash like the following can happen:

[   88.433133] Data bus error, epc == 80221c28, ra == 83314e60
[   88.438895] Oops[#1]:
[   88.441246] CPU: 0 PID: 7263 Comm: sh Not tainted 4.14.195 #0
[   88.447174] task: 838a1c20 task.stack: 82d5e000
[   88.451847] $ 0   : 00000000 00000030 deadc0de 83141de4
[   88.457248] $ 4   : b810a2c4 0000a2c4 83230fd4 00000000
[   88.462652] $ 8   : 0000000a 00000000 00000001 00000000
[   88.468055] $12   : 7f8ef318 00000000 00000000 77f802a0
[   88.473457] $16   : 83230080 00000002 0000001b 83230080
[   88.478861] $20   : 83a1c3f8 00841000 77f7adb0 ffffff92
[   88.484263] $24   : 00000fa4 77edd860
[   88.489665] $28   : 82d5e000 82d5fda8 00000000 83314e60
[   88.495070] Hi    : 00000000
[   88.498044] Lo    : 00000000
[   88.501040] epc   : 80221c28 ioread32+0x8/0x10
[   88.505671] ra    : 83314e60 ath9k_hw_loadnf+0x88/0x520 [ath9k_hw]
[   88.512049] Status: 1000fc03 KERNEL EXL IE
[   88.516369] Cause : 5080801c (ExcCode 07)
[   88.520508] PrId  : 00019374 (MIPS 24Kc)
[   88.524556] Modules linked in: ath9k ath9k_common pppoe ppp_async l2tp_ppp cdc_mbim batman_adv ath9k_hw ath sr9700 smsc95xx sierra_net rndis_host qmi_wwan pppox ppp_generic pl2303 nf_conntrack_ipv6 mcs7830 mac80211 kalmia iptable_nat ipt_REJECT ipt_MASQUERADE huawei_cdc_ncm ftdi_sio dm9601 cfg80211 cdc_subset cdc_ncm cdc_ether cdc_eem ax88179_178a asix xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_length xt_hl xt_ecn xt_dscp xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_NETMAP xt_LOG xt_HL xt_FLOWOFFLOAD xt_DSCP xt_CLASSIFY usbserial usbnet usbhid slhc rtl8150 r8152 pegasus nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_flow_table_hw nf_flow_table nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack
[   88.597894]  libcrc32c kaweth iptable_mangle iptable_filter ipt_ECN ipheth ip_tables hso hid_generic crc_ccitt compat cdc_wdm cdc_acm br_netfilter hid evdev input_core nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 l2tp_netlink l2tp_core udp_tunnel ip6_udp_tunnel xfrm6_mode_tunnel xfrm6_mode_transport xfrm6_mode_beet ipcomp6 xfrm6_tunnel esp6 ah6 xfrm4_tunnel xfrm4_mode_tunnel xfrm4_mode_transport xfrm4_mode_beet ipcomp esp4 ah4 tunnel6 tunnel4 tun xfrm_user xfrm_ipcomp af_key xfrm_algo sha256_generic sha1_generic jitterentropy_rng drbg md5 hmac echainiv des_generic deflate zlib_inflate zlib_deflate cbc authenc crypto_acompress ehci_platform ehci_hcd gpio_button_hotplug usbcore nls_base usb_common crc16 mii aead crypto_null cryptomgr crc32c_generic
[   88.671671]  crypto_hash
[   88.674292] Process sh (pid: 7263, threadinfo=82d5e000, task=838a1c20, tls=77f81efc)
[   88.682279] Stack : 00008060 00000008 00000200 00000000 00000000 00000000 00000000 00000002
[   88.690916]         80500000 83230080 82d5fe22 00841000 77f7adb0 00000000 00000000 83156858
[   88.699553]         00000000 8352fa00 83ad62b0 835302a8 00000000 300a00f8 00000003 82d5fe38
[   88.708190]         82d5fef4 00000001 77f54dc4 77f80000 77f7adb0 c79fe901 00000000 00000000
[   88.716828]         80510000 00000002 00841000 77f54dc4 77f80000 801ce4cc 0000000b 41824292
[   88.725465]         ...
[   88.727994] Call Trace:
[   88.730532] [<80221c28>] ioread32+0x8/0x10
[   88.734765] Code: 00000000  8c820000  0000000f <03e00008> 00000000  08088708  00000000  aca40000  03e00008
[   88.744846]
[   88.746464] ---[ end trace db226b2de1b69b9e ]---
[   88.753477] Kernel panic - not syncing: Fatal exception
[   88.759981] Rebooting in 3 seconds..

The "REG_READ(ah, AR_PHY_AGC_CONTROL)" in ath9k_hw_loadnf() does not
like being called when the hardware is asleep, leading to this crash.

The easiest way to reproduce this is trying to set nf_override while
the hardware is down:

  $ ip link set down dev wlan0
  $ echo "-85" > /sys/kernel/debug/ieee80211/phy0/ath9k/nf_override

Fixing this crash by waking the hardware up before trying to set the
noise floor. Similar to what other ath9k debugfs files do.

Tested on a Lima board from 8devices, which has a QCA 4531 chipset.

Fixes: b90189759a ("ath9k: add noise floor override option")
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Linus Lüssing <ll@simonwunderlich.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210209184352.4272-1-linus.luessing@c0d3.blue
2021-02-11 08:49:45 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-02 14:21:31 -08:00
block block-5.11-2021-01-29 2021-01-29 13:50:06 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto X.509: Fix crash caused by NULL pointer 2021-01-20 11:33:51 -08:00
Documentation net: dsa: automatically bring up DSA master when opening user port 2021-02-06 14:42:57 -08:00
drivers ath9k: fix data bus crash when setting nf_override via debugfs 2021-02-11 08:49:45 +02:00
fs Networking fixes for 5.11-rc7, including fixes from bpf and mac80211 2021-02-02 10:26:09 -08:00
include ssb: Use true and false for bool variable 2021-02-08 13:23:42 +02:00
init Revert "init/console: Use ttynull as a fallback when there is no console" 2021-01-08 11:02:18 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-02 14:21:31 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-01-28 17:09:31 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: page_frag: Introduce page_frag_alloc_align() 2021-02-06 11:57:28 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2021-02-06 15:34:23 -08:00
samples bpf: Rename BPF_XADD and prepare to encode other atomics in .imm 2021-01-14 18:34:29 -08:00
scripts Kbuild fixes for v5.11 2021-01-10 13:24:55 -08:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-16 15:11:35 -05:00
sound ALSA: hda/via: Apply the workaround generically for Clevo machines 2021-01-26 18:05:03 +01:00
tools selftests: mptcp: add command line arguments for mptcp_join.sh 2021-02-06 14:35:47 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM/arm64 fixes for 5.11, take #2 2021-01-25 18:52:01 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-01-29 15:00:23 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap mailmap: remove the "repo-abbrev" comment 2021-01-26 11:40:17 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: dccp: move Gerrit Renker to CREDITS 2021-01-14 10:53:49 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: dsa: add a second tagger for Ocelot switches based on tag_8021q 2021-01-29 21:25:27 -08:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-02 14:21:31 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.