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Subject: Re: [PATCH] net: called rtnl_unlock() before runpm resumes devices
To:     AceLan Kao <acelan.kao@canonical.com>
Cc:     Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andriin@fb.com>, Wei Wang <weiwan@google.com>,
        Cong Wang <cong.wang@bytedance.com>,
        Taehee Yoo <ap420073@gmail.com>,
        =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <9caae1c4-7132-4827-ef36-7aade74e4084@gmail.com>
Date:   Mon, 26 Apr 2021 10:42:25 +0200
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On 26.04.2021 09:36, AceLan Kao wrote:
> Heiner Kallweit <hkallweit1@gmail.com> 於 2021年4月25日 週日 上午4:07寫道：
>>
>> On 23.04.2021 05:42, AceLan Kao wrote:
>>> Heiner Kallweit <hkallweit1@gmail.com> 於 2021年4月22日 週四 下午3:09寫道：
>>>>
>>>> On 22.04.2021 08:30, AceLan Kao wrote:
>>>>> Yes, should add
>>>>>
>>>>> Fixes: 9474933caf21 ("igb: close/suspend race in netif_device_detach")
>>>>> and also
>>>>> Fixes: 9513d2a5dc7f ("igc: Add legacy power management support")
>>>>>
>>>> Please don't top-post. Apart from that:
>>>> If the issue was introduced with driver changes, then adding a workaround
>>>> in net core may not be the right approach.
>>> It's hard to say who introduces this issue, we probably could point
>>> our finger to below commit
>>> bd869245a3dc net: core: try to runtime-resume detached device in __dev_open
>>>
>>> This calling path is not usual, in my case, the NIC is not plugged in
>>> any Ethernet cable,
>>> and we are doing networking tests on another NIC on the system. So,
>>> remove the rtnl lock from igb driver will affect other scenarios.
>>>
>>>>
>>>>> Jakub Kicinski <kuba@kernel.org> 於 2021年4月21日 週三 上午3:27寫道：
>>>>>>
>>>>>> On Tue, 20 Apr 2021 10:34:17 +0200 Eric Dumazet wrote:
>>>>>>> On Tue, Apr 20, 2021 at 9:54 AM AceLan Kao <acelan.kao@canonical.com> wrote:
>>>>>>>>
>>>>>>>> From: "Chia-Lin Kao (AceLan)" <acelan.kao@canonical.com>
>>>>>>>>
>>>>>>>> The rtnl_lock() has been called in rtnetlink_rcv_msg(), and then in
>>>>>>>> __dev_open() it calls pm_runtime_resume() to resume devices, and in
>>>>>>>> some devices' resume function(igb_resum,igc_resume) they calls rtnl_lock()
>>>>>>>> again. That leads to a recursive lock.
>>>>>>>>
>>>>>>>> It should leave the devices' resume function to decide if they need to
>>>>>>>> call rtnl_lock()/rtnl_unlock(), so call rtnl_unlock() before calling
>>>>>>>> pm_runtime_resume() and then call rtnl_lock() after it in __dev_open().
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> Hi Acelan
>>>>>>>
>>>>>>> When was the bugg added ?
>>>>>>> Please add a Fixes: tag
>>>>>>
>>>>>> For immediate cause probably:
>>>>>>
>>>>>> Fixes: 9474933caf21 ("igb: close/suspend race in netif_device_detach")
>>>>>>
>>>>>>> By doing so, you give more chances for reviewers to understand why the
>>>>>>> fix is not risky,
>>>>>>> and help stable teams work.
>>>>>>
>>>>>> IMO the driver lacks internal locking. Taking 看rtnl from resume is just
>>>>>> one example, git history shows many more places that lacked locking and
>>>>>> got papered over with rtnl here.
>>>>
>>
>> You could alternatively try the following. It should avoid the deadlock,
>> and when runtime-resuming if __IGB_DOWN is set all we do is marking the
>> net_device as present (because of PCI D3 -> D0 transition).
>> I do basically the same in r8169 and it works as intended.
>>
>> Disclaimer: I don't have an igb-driven device and therefore can't test
>> the proposal.
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
>> index 038a9fd1a..21436626a 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -9300,6 +9300,14 @@ static int __maybe_unused igb_runtime_suspend(struct device *dev)
>>
>>  static int __maybe_unused igb_runtime_resume(struct device *dev)
>>  {
>> +       struct net_device *netdev = dev_get_drvdata(dev);
>> +       struct igb_adapter *adapter = netdev_priv(netdev);
>> +
>> +       if (test_bit(__IGB_DOWN, &adapter->state)) {
>> +               netif_device_attach(netdev);
>> +               return 0;
>> +       }
>> +
>>         return igb_resume(dev);
>>  }
>>
>> --
>> 2.31.1
>>
> 
> Hi Heiner,
> 
> I encountered below error after applied your patch.
> 
Presumably similar changes are needed also for the runtime_suspend callback.
If __IGB_DOWN is set, I think just the net_device needs to be detached.


> [  121.489970] u kernel: ------------[ cut here ]------------
> [  121.489979] u kernel: igb 0000:05:00.0: disabling already-disabled device
> [  121.490008] u kernel: WARNING: CPU: 7 PID: 258 at
> drivers/pci/pci.c:2146 pci_disable_device+0x91/0xb0
> [  121.490028] u kernel: Modules linked in: rfcomm cmac algif_hash
> algif_skcipher af_alg bnep btusb btrtl btbcm btintel bluetooth
> ecdh_generic ecc joydev input_leds inte
> l_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp
> coretemp ath10k_pci ath10k_core kvm_intel ath mac80211 kvm
> snd_sof_pci_intel_tgl snd_soc_acpi_intel_ma
> tch snd_sof_intel_hda_common nls_iso8859_1 soundwire_intel
> soundwire_generic_allocation soundwire_cadence soundwire_bus
> snd_sof_pci snd_soc_acpi snd_sof snd_soc_core snd
> _hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi
> crct10dif_pclmul crc32_pclmul snd_sof_xtensa_dsp ghash_clmulni_intel
> ledtrig_audio aesni_intel snd_hda_intel
> libarc4 crypto_simd snd_intel_dspcfg snd_intel_sdw_acpi cryptd
> snd_hda_codec cfg80211 mei_hdcp snd_hwdep snd_hda_core
> intel_wmi_thunderbolt snd_pcm wmi_bmof snd_seq inte
> l_cstate efi_pstore snd_timer snd_seq_device ee1004 mei_me snd mei
> ucsi_acpi soundcore typec_ucsi typec wmi mac_hid acpi_pad acpi_tad
> sch_fq_codel
> [  121.490314] u kernel:  parport_pc ppdev lp parport ip_tables
> x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456
> async_raid6_recov async_memcpy async_
> pq async_xor async_tx libcrc32c xor raid6_pq raid1 raid0 multipath
> linear hid_generic usbhid hid i915 drm_kms_helper syscopyarea
> sysfillrect sysimgblt fb_sys_fops cec rc
> _core igb drm nvme e1000e nvme_core i2c_i801 dca i2c_smbus
> i2c_algo_bit intel_lpss_pci intel_lpss ahci idma64 video xhci_pci
> libahci virt_dma xhci_pci_renesas pinctrl_ti
> gerlake
> [  121.490508] u kernel: CPU: 7 PID: 258 Comm: kworker/7:2 Tainted: G
>    U            5.12.0-rc7+ #79
> [  121.490518] u kernel: Hardware name: Dell Inc. OptiPlex 7090/, BIOS
> 0.12.80 02/23/2021
> [  121.490525] u kernel: Workqueue: pm pm_runtime_work
> [  121.490540] u kernel: RIP: 0010:pci_disable_device+0x91/0xb0
> [  121.490550] u kernel: Code: 4d 85 e4 75 07 4c 8b a3 c8 00 00 00 48
> 8d bb c8 00 00 00 e8 61 8d 17 00 4c 89 e2 48 c7 c7 60 5a e0 a5 48 89
> c6 e8 9b a3 59 00 <0f> 0b eb 8
> d 48 89 df e8 e3 fe ff ff 80 a3 49 0a 00 00 df 5b 41 5c
> [  121.490558] u kernel: RSP: 0018:ffffb76b4169fc90 EFLAGS: 00010286
> [  121.490569] u kernel: RAX: 0000000000000000 RBX: ffff9e2581ee6000
> RCX: 0000000000000027
> [  121.490576] u kernel: RDX: 0000000000000027 RSI: ffffffffa493bca0
> RDI: ffff9e27073e89b8
> [  121.490582] u kernel: RBP: ffffb76b4169fca0 R08: ffff9e27073e89b0
> R09: 0000000000000000
> [  121.490588] u kernel: R10: 0000000000000000 R11: 0000000000000001
> R12: ffff9e2581af7c80
> [  121.490594] u kernel: R13: ffff9e2581ee6000 R14: ffff9e25a0914000
> R15: ffff9e25a0915280
> [  121.490600] u kernel: FS:  0000000000000000(0000)
> GS:ffff9e2707200000(0000) knlGS:0000000000000000
> [  121.490608] u kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  121.490614] u kernel: CR2: 00007ff86ec8d024 CR3: 0000000189c28002
> CR4: 0000000000770ee0
> [  121.490621] u kernel: PKRU: 55555554
> [  121.490626] u kernel: Call Trace:
> [  121.490638] u kernel:  __igb_shutdown+0xf2/0x1c0 [igb]
> [  121.490676] u kernel:  igb_runtime_suspend+0x1c/0x20 [igb]
> [  121.490703] u kernel:  pci_pm_runtime_suspend+0x63/0x180
> [  121.490715] u kernel:  ? pci_pm_runtime_resume+0x90/0x90
> [  121.490727] u kernel:  __rpm_callback+0xc7/0x140
> [  121.490740] u kernel:  rpm_callback+0x57/0x80
> [  121.490750] u kernel:  ? pci_pm_runtime_resume+0x90/0x90
> [  121.490759] u kernel:  rpm_suspend+0x119/0x640
> [  121.490774] u kernel:  pm_runtime_work+0x64/0xc0
> [  121.490784] u kernel:  process_one_work+0x2af/0x5d0
> [  121.490803] u kernel:  worker_thread+0x4d/0x3e0
> [  121.490814] u kernel:  ? process_one_work+0x5d0/0x5d0
> [  121.490825] u kernel:  kthread+0x12a/0x160
> [  121.490834] u kernel:  ? kthread_park+0x90/0x90
> [  121.490844] u kernel:  ret_from_fork+0x1f/0x30
> [  121.490867] u kernel: irq event stamp: 0[  121.490871] u kernel:
> hardirqs last  enabled at (0): [<0000000000000000>] 0x0
> [  121.490916] u kernel: hardirqs last disabled at (0):
> [<ffffffffa489ea44>] copy_process+0x714/0x1cc0
> [  121.490929] u kernel: softirqs last  enabled at (0):
> [<ffffffffa489ea44>] copy_process+0x714/0x1cc0
> [  121.490938] u kernel: softirqs last disabled at (0): [<0000000000000000>] 0x0
> [  121.490949] u kernel: ---[ end trace a9c7ffc27c226979 ]---
>