[PATCH] UBUNTU: SAUCE: Bluetooth: Make request workqueue freezable

Fri Jul 28 08:20:02 UTC 2017

On 28.07.2017 05:07, AceLan Kao wrote:
> Hi Stefan,
> 
> The maintainer think this patch is just papering over it, not a real fix.
> The maintainer think to fix this issue is to have the USB subsystem
> delay the probe() callback if we tell it to,
> or just have request_firmware() actually sleep until userspace is ready.
> But I think this sauce patch is a tiny and tricky fix that can just fit SRU.
> 
> Recently, there is a fix introduced in 4.13-rc1 which can fix this issue
>    06a45a9 firmware: move umh try locks into the umh code
> It's the final commit of a series firmware patches.
> Compare to the 2 different fixes, the sauce patch is more convinceable
> to me for Xenial.
> 
> The machine the patch author has is with broadcom bt chip, and mine is atheros,
> I can find some machines with intel, brcm, and ath bt to run the test next week.

Hi Acelan,

thanks for the background of this. If you could do those quick tests and just
report back here that would be great. It probably sounds like a lot of hassle
for such a small change but those simple changes sometimes can be the worst. The
meaning of making a work queue freezable is not obvious so my gut feeling is
that we should at least check a little broader whether this does not introduce
something weird.

Thanks,
Stefan
> 
> BTW, The Alan Stern says the 2 fixes that maintainer mentioned won't work, and
> the conclusion at that time is to cache the firmware data while the
> first successful loading.
> <quote>
>>>>  I would rather have the USB subsystem delay the probe()
>>>> callback if we tell it to.
> 
> This is possible.  I am not sure it would be the right thing to do,
> though.  What happens if the probe routine gets called early on during
> the boot-up procedure, before userspace is up and running?  The same
> thing should happen here.
> 
>>>>  Of just have request_firmware()
>>>> actually sleep until userspace is ready. Seriously, why is
>>>> request_firmware not just sleeping for us.
> 
> It won't work.  The request_firmware call is part of the probe
> sequence, which in turn is part of the resume sequence.  Userspace
> doesn't start running again until the resume sequence is finished.  If
> request_firmware waited for userspace, it would hang.
> </quote>
> 
> Best regards,
> AceLan Kao.
> 
> 2017-07-27 23:04 GMT+08:00 Stefan Bader <stefan.bader at canonical.com>:
>> On 27.07.2017 04:36, AceLan Kao wrote:
>>> From: Laura Abbott <labbott at fedoraproject.org>
>>>
>>> BugLink: http://bugs.launchpad.net/bugs/1706833
>>>
>>> We've received a number of reports of warnings when coming
>>> out of suspend with certain bluetooth firmware configurations:
>>>
>>> WARNING: CPU: 3 PID: 3280 at drivers/base/firmware_class.c:1126
>>> _request_firmware+0x558/0x810()
>>> Modules linked in: ccm ip6t_rpfilter ip6t_REJECT nf_reject_ipv6
>>> xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter
>>> ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6
>>> ip6table_mangle ip6table_security ip6table_raw ip6table_filter
>>> ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4
>>> nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw
>>> binfmt_misc bnep intel_rapl iosf_mbi arc4 x86_pkg_temp_thermal
>>> snd_hda_codec_hdmi coretemp kvm_intel joydev snd_hda_codec_realtek
>>> iwldvm snd_hda_codec_generic kvm iTCO_wdt mac80211 iTCO_vendor_support
>>> snd_hda_intel snd_hda_controller snd_hda_codec crct10dif_pclmul
>>> snd_hwdep crc32_pclmul snd_seq crc32c_intel ghash_clmulni_intel uvcvideo
>>> snd_seq_device iwlwifi btusb videobuf2_vmalloc snd_pcm videobuf2_core
>>>  serio_raw bluetooth cfg80211 videobuf2_memops sdhci_pci v4l2_common
>>> videodev thinkpad_acpi sdhci i2c_i801 lpc_ich mfd_core wacom mmc_core
>>> media snd_timer tpm_tis hid_logitech_hidpp wmi tpm rfkill snd mei_me mei
>>> shpchp soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc i915
>>> i2c_algo_bit drm_kms_helper e1000e drm hid_logitech_dj ptp pps_core
>>> video
>>> CPU: 3 PID: 3280 Comm: kworker/u17:0 Not tainted 3.19.3-200.fc21.x86_64
>>> Hardware name: LENOVO 343522U/343522U, BIOS GCET96WW (2.56 ) 10/22/2013
>>> Workqueue: hci0 hci_power_on [bluetooth]
>>>  0000000000000000 0000000089944328 ffff88040acffb78 ffffffff8176e215
>>>  0000000000000000 0000000000000000 ffff88040acffbb8 ffffffff8109bc1a
>>>  0000000000000000 ffff88040acffcd0 00000000fffffff5 ffff8804076bac40
>>> Call Trace:
>>>  [<ffffffff8176e215>] dump_stack+0x45/0x57
>>>  [<ffffffff8109bc1a>] warn_slowpath_common+0x8a/0xc0
>>>  [<ffffffff8109bd4a>] warn_slowpath_null+0x1a/0x20
>>>  [<ffffffff814dbe78>] _request_firmware+0x558/0x810
>>>  [<ffffffff814dc165>] request_firmware+0x35/0x50
>>>  [<ffffffffa03a7886>] btusb_setup_bcm_patchram+0x86/0x590 [btusb]
>>>  [<ffffffff814d40e6>] ? rpm_idle+0xd6/0x230
>>>  [<ffffffffa04d4801>] hci_dev_do_open+0xe1/0xa90 [bluetooth]
>>>  [<ffffffff810c51dd>] ? ttwu_do_activate.constprop.90+0x5d/0x70
>>>  [<ffffffffa04d5980>] hci_power_on+0x40/0x200 [bluetooth]
>>>  [<ffffffff810b487c>] process_one_work+0x14c/0x3f0
>>>  [<ffffffff810b52f3>] worker_thread+0x53/0x470
>>>  [<ffffffff810b52a0>] ? rescuer_thread+0x300/0x300
>>>  [<ffffffff810ba548>] kthread+0xd8/0xf0
>>>  [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0
>>>  [<ffffffff81774958>] ret_from_fork+0x58/0x90
>>>  [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0
>>>
>>> This occurs after every resume.
>>>
>>> When resuming, the bluetooth stack calls hci_register_dev,
>>> allocates a new workqueue, and immediately schedules the
>>> power_on on the newly created workqueue. Since the new
>>> workqueue is not freezable, the work runs immediately and
>>> triggers the warning since resume is still happening and
>>> usermodehelper has not yet been re-enabled. Fix this by
>>> making the request workqueue freezable. This ensures
>>> the work will not run until unfreezing occurs and usermodehelper
>>> is re-enabled.
>>>
>>> Signed-off-by: Laura Abbott <labbott at fedoraproject.org>
>>> Signed-off-by: AceLan Kao <acelan.kao at canonical.com>
>>> ---
>>
>> Why was this change not accepted upstream? Is every laptop with bluetooth
>> affected? Did you do some broader testing (not only on that one hw)?
>>
>> -Stefan
>>>  net/bluetooth/hci_core.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
>>> index eea796c..780a76c 100644
>>> --- a/net/bluetooth/hci_core.c
>>> +++ b/net/bluetooth/hci_core.c
>>> @@ -3365,7 +3365,7 @@ int hci_register_dev(struct hci_dev *hdev)
>>>       }
>>>
>>>       hdev->req_workqueue = alloc_workqueue("%s", WQ_HIGHPRI | WQ_UNBOUND |
>>> -                                           WQ_MEM_RECLAIM, 1, hdev->name);
>>> +                                           WQ_MEM_RECLAIM | WQ_FREEZABLE, 1, hdev->name);
>>>       if (!hdev->req_workqueue) {
>>>               destroy_workqueue(hdev->workqueue);
>>>               error = -ENOMEM;
>>>
>>
>>
>>
>> --
>> kernel-team mailing list
>> kernel-team at lists.ubuntu.com
>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>>

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