linux-kernel - Re: [BUG] ftrace: available_filter_functions empty after unloading module

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Date:	Mon, 10 Dec 2012 12:45:56 +0100
From:	"Piotr Haber" <phaber@...adcom.com>
To:	"Steven Rostedt" <rostedt@...dmis.org>
cc:	"Frederic Weisbecker" <fweisbec@...il.com>,
	"Ingo Molnar" <mingo@...hat.com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] ftrace: available_filter_functions empty after
 unloading module

On 12/07/12 14:57, Steven Rostedt wrote:
> On Fri, 2012-12-07 at 09:06 +0100, Piotr Haber wrote:
>> On 12/06/12 19:10, Steven Rostedt wrote:
> 
>> Hi,
>> sorry to disappoint you, but there is really nothing more around the
>> warning.
>> I know it is not helpful, maybe i can do some more tracing if you tell
>> me how
> 
> Ah, I was looking at a different version of ftrace.c and didn't get the
> correct line where the warning was. Yeah, that warning that you hit was
> something different, and it doesn't give more info there. :-/
> 
>>
>> Here it is with broader context:
> 
> Thanks
> 
>>
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211: Calling CRDA to update world
>> regulatory domain
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211: World regulatory domain updated:
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (start_freq - end_freq @
>> bandwidth), (max_antenna_gain, max_eirp)
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (2402000 KHz - 2472000 KHz
>> @ 40000 KHz), (300 mBi, 2000 mBm)
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (2457000 KHz - 2482000 KHz
>> @ 20000 KHz), (300 mBi, 2000 mBm)
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (2474000 KHz - 2494000 KHz
>> @ 20000 KHz), (300 mBi, 2000 mBm)
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (5170000 KHz - 5250000 KHz
>> @ 40000 KHz), (300 mBi, 2000 mBm)
>> Dec  6 15:22:27 lb-bun-52 kernel: cfg80211:   (5735000 KHz - 5835000 KHz
>> @ 40000 KHz), (300 mBi, 2000 mBm)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus0: Found chip with id 0xA8D8,
>> rev 0x01 and package 0x0A
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus0: Core 0 found: ChipCommon
>> (manuf 0x4BF, id 0x800, rev 0x22, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus0: Core 1 found: IEEE 802.11
>> (manuf 0x4BF, id 0x812, rev 0x17, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus0: Core 2 found: PCIe (manuf
>> 0x4BF, id 0x820, rev 0x0F, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus0: Bus registered
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus1: Found chip with id 0x4313,
>> rev 0x01 and package 0x08
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus1: Core 0 found: ChipCommon
>> (manuf 0x4BF, id 0x800, rev 0x24, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus1: Core 1 found: IEEE 802.11
>> (manuf 0x4BF, id 0x812, rev 0x18, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus1: Core 2 found: PCIe (manuf
>> 0x4BF, id 0x820, rev 0x11, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus1: Bus registered
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus2: Found chip with id 0x4313,
>> rev 0x01 and package 0x08
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus2: Core 0 found: ChipCommon
>> (manuf 0x4BF, id 0x800, rev 0x24, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus2: Core 1 found: IEEE 802.11
>> (manuf 0x4BF, id 0x812, rev 0x18, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus2: Core 2 found: PCIe (manuf
>> 0x4BF, id 0x820, rev 0x11, class 0x0)
>> Dec  6 15:22:27 lb-bun-52 kernel: bcma: bus2: Bus registered
>> Dec  6 15:22:27 lb-bun-52 kernel: brcmsmac bcma0:0: mfg 4bf core 812 rev
>> 23 class 0 irq 16
>> Dec  6 15:22:27 lb-bun-52 kernel: ieee80211 phy0: Selected rate control
>> algorithm 'minstrel_ht'
>> Dec  6 15:22:27 lb-bun-52 kernel: Registered led device: brcmsmac-phy0:radio
>> Dec  6 15:22:27 lb-bun-52 kernel: brcmsmac bcma1:0: mfg 4bf core 812 rev
>> 24 class 0 irq 17
>> Dec  6 15:22:27 lb-bun-52 kernel: ieee80211 phy1: Selected rate control
>> algorithm 'minstrel_ht'
>> Dec  6 15:22:27 lb-bun-52 kernel: Registered led device: brcmsmac-phy1:radio
>> Dec  6 15:22:27 lb-bun-52 kernel: brcmsmac bcma2:0: mfg 4bf core 812 rev
>> 24 class 0 irq 16
>> Dec  6 15:22:27 lb-bun-52 kernel: ieee80211 phy2: Selected rate control
>> algorithm 'minstrel_ht'
>> Dec  6 15:22:27 lb-bun-52 kernel: Registered led device: brcmsmac-phy2:radio
>> Dec  6 15:22:34 lb-bun-52 kernel: ------------[ cut here ]------------
>> Dec  6 15:22:34 lb-bun-52 kernel: WARNING: at kernel/trace/ftrace.c:1564
>> __ftrace_hash_rec_update.part.34+0x20d/0x250()
>> Dec  6 15:22:34 lb-bun-52 kernel: Hardware name: Latitude E6420
>> Dec  6 15:22:34 lb-bun-52 kernel: Modules linked in: brcmsmac(O)
>> brcmutil(O) bcma(O) mac80211(O) cfg80211(O) rfkill(O) arc4 cordic fuse
>> ip6table_filter ip6_tables ebtable_nat ebtables nf_conntrack_i
>> pv4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_CHECKSUM
>> iptable_mangle iptable_filter ip_tables bridge stp llc
>> snd_hda_codec_hdmi snd_hda_codec_idt coretemp kvm_intel snd_hda_intel
>> kvm snd_h
>> da_codec nouveau ttm drm_kms_helper drm ghash_clmulni_intel aesni_intel
>> snd_hwdep snd_pcm_oss snd_mixer_oss snd_pcm ablk_helper snd_seq_dummy
>> snd_seq_oss i2c_algo_bit i2c_core mxm_wmi cryptd lrw pl2
>> 303 usbserial snd_seq_midi aes_x86_64 snd_rawmidi xts snd_seq_midi_event
>> gf128mul snd_seq video snd_timer ppdev dell_laptop dell_wmi serio_raw
>> sparse_keymap dcdbas snd_seq_device snd microcode lpc_i
>> ch mfd_core parport_pc wmi soundcore snd_page_alloc lp parport ipv6 ext4
>> mbcache jbd2 sd_mod crc_t10dif sr_mod cdrom crc32c_intel ahci libahci
>> sdhci_pci sdhci mmc_core e1000e [last unloaded: rfkill]
>> Dec  6 15:22:34 lb-bun-52 kernel: Pid: 2498, comm: bash Tainted: G
>>      O 3.7.0-rc8 #3
>> Dec  6 15:22:34 lb-bun-52 kernel: Call Trace:
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff810574ff>]
>> warn_slowpath_common+0x7f/0xc0
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff8105755a>]
>> warn_slowpath_null+0x1a/0x20
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff810fdd7d>]
>> __ftrace_hash_rec_update.part.34+0x20d/0x250
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff810fea15>]
>> ftrace_hash_move+0x1c5/0x1e0
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff81100388>]
>> ftrace_regex_release+0x98/0x150
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff8118f7ac>] __fput+0xcc/0x290
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff8118f97e>] ____fput+0xe/0x10
>> Dec  6 15:22:34 lb-bun-52 kernel: [<ffffffff810798e7>]
>> task_work_run+0xa7/0xe0
> 
> So you unloaded a module that you were tracing, correct? Hmm, the
> warning that you hit was an accounting error. The accounting of what
> functions are traced and what isn't. For some reason it tried to disable
> a function that wasn't being traced.
Yes, it happens when i unload a module that i traced before

> Can you easily reproduce this? If so, can you give my your .config and
> the steps you used to trigger it.
Not 100% but it happens often enough to be annoying
Attached is the config
As for reproduction, i load the brcmsmac module, add all it symbols to
set_ftrace_filter, associate with AP and unload the module
nothing fancy, i use 'function' tracer

BTW.
is it a feature that when there is a traceon trigger added on a function
from module (like: echo 'brcms_free:traceon' > set_ftrace_filter) after
module unloading it is not removed?
just function name gets changed to symbol address

Piotr



View attachment "config.3.7-rc8" of type "text/plain" (115760 bytes)