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

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Message-ID: <20231208175312.GA803148@bhelgaas>
Date:   Fri, 8 Dec 2023 11:53:12 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Johan Hovold <johan+linaro@...nel.org>
Cc:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Nirmal Patel <nirmal.patel@...ux.intel.com>,
        Jonathan Derrick <jonathan.derrick@...ux.dev>,
        linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/6] PCI: Fix deadlocks when enabling ASPM

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
> 
> 
> Changes in v2
>  - fix up the function name in a kernel doc comment as reported by the
>    kernel test robot <lkp@...el.com>
> 
> 
> 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
> 
>  drivers/pci/controller/dwc/pcie-qcom.c |  7 ++-
>  drivers/pci/controller/vmd.c           |  2 +-
>  drivers/pci/pcie/aspm.c                | 65 +++++++++++++++++++-------
>  include/linux/pci.h                    |  3 ++
>  4 files changed, 56 insertions(+), 21 deletions(-)

Applied to for-linus for v6.7, thanks, Johan!