Re: [PATCH v2 0/6] PCI: Fix deadlocks when enabling ASPM

Linux regression tracking #update (Thorsten Leemhuis)
2023-12-10T12:35:57Z

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On 07.12.23 14:25, Johan Hovold wrote:
> On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote:
>> The pci_enable_link_state() helper is currently only called from
>> pci_walk_bus(), something which can lead to a deadlock as both helpers
>> take a pci_bus_sem read lock.
>>
>> Add a new locked helper which can be called with the read lock held and
>> fix up the two current users (the second is new in 6.7-rc1).
>>
>> Note that there are no users left of the original unlocked variant after
>> this series, but I decided to leave it in place for now (e.g. to mirror
>> the corresponding helpers to disable link states).
>>
>> Included are also a couple of related cleanups.
>
>> Johan Hovold (6):
>> PCI/ASPM: Add locked helper for enabling link state
>> PCI: vmd: Fix deadlock when enabling ASPM
>> PCI: qcom: Fix deadlock when enabling ASPM
>> PCI: qcom: Clean up ASPM comment
>> PCI/ASPM: Clean up disable link state parameter
>> PCI/ASPM: Add lockdep assert to link state helper
>
> Could we get this merged for 6.7-rc5? Even if the risk of a deadlock is
> not that great, this bug prevents using lockdep on Qualcomm platforms so
> that more locking issues can potentially make their way into the kernel.
>
> And for Qualcomm platforms, this is a regression in 6.7-rc1.
>
> #regzbot introduced: 9f4f3dfad8cf

Fixes are now here:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=for-linus

#regzbot fix: 075268be58232b0a2ae
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
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