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Subject: Re: [RFC 0/3] acpipcihp: fix kernel crash on 2nd resume
From:   Woody Suwalski <terraluna977@gmail.com>
To:     Igor Mammedov <imammedo@redhat.com>, linux-kernel@vger.kernel.org
Cc:     bhelgaas@google.com, linux-pci@vger.kernel.org, mst@redhat.com,
        Woody Suwalski <terraluna977@gmail.com>
References: <20230725113938.2277420-1-imammedo@redhat.com>
 <88a06e12-600a-a4bd-f216-44753965ce48@gmail.com>
Message-ID: <7bbe2e5f-411c-6936-5d4b-c128795fb5d4@gmail.com>
Date:   Tue, 25 Jul 2023 11:41:11 -0400
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Woody Suwalski wrote:
> Igor Mammedov wrote:
>> Changelog:
>>    * split out debug patch into a separate one with extra printk added
>>    * fixed inverte bus->self check (probably a reason why it didn't 
>> work before)
>>
>>
>> 1/3 debug patch
>> 2/3 offending patch
>> 3/3 potential fix
>>    I added more files to trace, add following to kernel CLI
>>     dyndbg="file drivers/pci/access.c +p; file 
>> drivers/pci/hotplug/acpiphp_glue.c +p; file drivers/pci/bus.c +p; 
>> file drivers/pci/pci.c +p; file drivers/pci/setup-bus.c +p; file 
>> drivers/acpi/bus.c +p" ignore_loglevel
>>
>> should be applied on top of
>>     e8afd0d9fccc PCI: pciehp: Cancel bringup sequence if card is not 
>> present
>>
>> apply a patch one by one and run testcase + capture dmesg after each 
>> patch
>> one shpould endup with 3 dmesg to ananlyse
>>   1st - old behaviour - no crash
>>   2nd - crash
>>   3rd - no crash hopefully
>>
>> Igor Mammedov (3):
>>    acpiphp: extra debug hack
>>    PCI: acpiphp: Reassign resources on bridge if necessary
>>    acpipcihp: use __pci_bus_assign_resources() if bus doesn't have 
>> bridge
>>
>>   drivers/pci/hotplug/acpiphp_glue.c | 23 ++++++++++++++++++-----
>>   1 file changed, 18 insertions(+), 5 deletions(-)
>>
> Actually applying patch1 is already creating the crash (why???), hence 
> I have added also dmesg-6.5-0.txt which shows a working condition 
> based on git e8afd0d9fccc level (acpiphp_glue in kernel 6.4)
>
> Patch3 did not fix the issue, it seems that the culprit is somewhere 
> else triggered by  "benign" patch1 :-(
>
> Also note about the trigger description in patch3: the dmesg trace on 
> Inspiron laptop is collected after the first wake from suspend to ram. 
> The consecutive  attempt to sleep results in a frozen system.
>
> Thanks, Woody
>
I think that in patch1 there is a problem in your debug statement 
acpi_handle_debug(...slot_name...) - it is masking the "old" issue.
when I commented out that line in hotplug_event(), it has worked ok (as 
was expected). I will redo the testing in ~2 hours...

Woody