Slow path warning for sta_info_insert_rcu()

[linus.luessing@…]

I'm running the current OpenWRT attitude adjustment version of compat wireless (rev. 34055 of the attitude adjustment branch, compat-wireless 2012-09-07 plus OpenWRT patches) on my Debian based laptop (3.2.0-2-amd64). It is configured with a single interface in adhoc mode, configured via iwconfig.

From time to time I see slow path warnings like the following in my dmesg output:

[2096868.357450] ------------[ cut here ]------------
[2096868.357469] WARNING: at /var/batman/compat-wireless/compat-wireless-2012-09-07/net/mac80211/sta_info.c:304 sta_info_insert_rcu+0x52/0x92 [mac80211]()
[2096868.357472] Hardware name: \xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff 
[2096868.357474] Modules linked in: batman_adv(O) ath9k_htc(O) ath9k(O) ath9k_common(O) ath9k_hw(O) ath(O) mac80211(O) cfg80211(O) compat(O) rfcomm bnep btusb snd_seq_dummy bluetooth msr tun ebt_ip6 ebt_dnat ebt_ip ebtable_filter cdc_ether usbnet mii eeprom_93cx6(O) crc_ccitt 8021q garp nfnetlink_log nfnetlink usblp cdc_phonet phonet cdc_acm sg ecb ip6table_filter ip6_tables ebtable_nat ebtables acpi_cpufreq mperf cpufreq_conservative cpufreq_userspace cpufreq_stats cpufreq_powersave binfmt_misc bridge stp kvm_intel kvm tcp_vegas iptable_filter ipt_REDIRECT xt_tcpudp iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack ip_tables x_tables coretemp firewire_sbp2 fuse ecryptfs snd_hda_codec_realtek snd_hda_intel snd_hda_codec arc4 snd_hwdep nouveau snd_pcm_oss snd_mixer_oss snd_pcm snd_page_alloc joydev snd_seq_midi snd_seq_midi_event r852 snd_rawmidi mxm_wmi snd_seq sm_common uvcvideo videodev snd_seq_device snd_timer snd ttm drm_kms_helper processor ac v4l2_compat_ioctl32 acer_wmi sparse_keymap nand drm i2c_i801 nand_ecc wmi nand_ids media r592 iTCO_wdt soundcore battery i2c_algo_bit rfkill evdev pcspkr memstick psmouse mtd i2c_core serio_raw video button power_supply iTCO_vendor_support ext4 crc16 jbd2 loop ext3 mbcache jbd sha256_generic cryptd aes_x86_64 aes_generic cbc dm_crypt dm_mod sd_mod crc_t10dif sr_mod cdrom usb_storage ata_generic uas firewire_ohci thermal thermal_sys sdhci_pci sdhci mmc_core firewire_core crc_itu_t ata_piix ahci libahci uhci_hcd libata scsi_mod ehci_hcd tg3 libphy usbcore usb_common [last unloaded: batman_adv]
[2096868.357614] Pid: 6487, comm: kworker/u:0 Tainted: G        W  O 3.2.0-2-amd64 #1
[2096868.357617] Call Trace:
[2096868.357625]  [<ffffffff81046861>] ? warn_slowpath_common+0x78/0x8c
[2096868.357635]  [<ffffffffa076af1f>] ? sta_info_insert_rcu+0x52/0x92 [mac80211]
[2096868.357645]  [<ffffffffa0771a88>] ? ieee80211_ibss_finish_sta+0x69/0xd6 [mac80211]
[2096868.357655]  [<ffffffffa0771b9f>] ? ieee80211_ibss_add_sta+0xaa/0xdb [mac80211]
[2096868.357665]  [<ffffffffa07722bc>] ? ieee80211_rx_bss_info+0x15d/0x4f4 [mac80211]
[2096868.357677]  [<ffffffffa0783a43>] ? ieee802_11_parse_elems_crc+0x43e/0x4ac [mac80211]
[2096868.357688]  [<ffffffffa07726fa>] ? ieee80211_rx_mgmt_beacon+0x4f/0x5b [mac80211]
[2096868.357699]  [<ffffffffa0772a65>] ? ieee80211_ibss_rx_queued_mgmt+0x24d/0x2da [mac80211]
[2096868.357704]  [<ffffffff81037e30>] ? set_next_entity+0x32/0x55
[2096868.357709]  [<ffffffff8100d02f>] ? load_TLS+0x7/0xa
[2096868.357713]  [<ffffffff8107068d>] ? arch_local_irq_save+0x11/0x17
[2096868.357724]  [<ffffffffa077469c>] ? ieee80211_iface_work+0x234/0x30f [mac80211]
[2096868.357734]  [<ffffffffa0774468>] ? ieee80211_wds_rx_queued_mgmt+0x1a2/0x1a2 [mac80211]
[2096868.357739]  [<ffffffff8105ae0a>] ? process_one_work+0x163/0x284
[2096868.357743]  [<ffffffff8105bdd2>] ? worker_thread+0xc2/0x145
[2096868.357746]  [<ffffffff8105bd10>] ? manage_workers.isra.23+0x15b/0x15b
[2096868.357750]  [<ffffffff8105ef0d>] ? kthread+0x76/0x7e
[2096868.357756]  [<ffffffff81350df4>] ? kernel_thread_helper+0x4/0x10
[2096868.357760]  [<ffffffff8105ee97>] ? kthread_worker_fn+0x139/0x139
[2096868.357764]  [<ffffffff81350df0>] ? gs_change+0x13/0x13
[2096868.357766] ---[ end trace 4fa096adab258535 ]---

[linus.luessing@…]

And according to lspci the wifi card is a: Atheros Communications Inc. AR928X Wireless Network Adapter (PCI-Express) (rev 01)

[linus.luessing@…]

And it's actually the WARN_ON() in sta_info_insert_check() called from sta_info_insert_rcu() and not the sta_info_insert_rcu() itself.

I added a printk() and noticed that the WARN_ON() gets triggered because sta->sta.addr and sdata->vif.addr are the same: They are both the MAC address of my own, same wlan0 adhoc interface, the interface I received this frame on (and where this frame was probably sent from before).

[nbd]

fixed in r38013

[jow]

Milestone Attitude Adjustment 12.09 deleted