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PCI: vmd: Fix potential deadlock when enabling ASPM 

commit 49de0dc87965079a8e2803ee4b39f9d946259423 upstream.

The vmd_pm_enable_quirk() helper is called from pci_walk_bus() during
probe to enable ASPM for controllers with VMD_FEAT_BIOS_PM_QUIRK set.

Since pci_walk_bus() already holds a pci_bus_sem read lock, use
pci_enable_link_state_locked() to enable link states in order to avoid a
potential deadlock (e.g. in case someone takes a write lock before
reacquiring the read lock).

Fixes: f492edb40b ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR")
Link: https://lore.kernel.org/r/20231128081512.19387-3-johan+linaro@kernel.org
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
[bhelgaas: add "potential" in subject since the deadlock has only been
reported by lockdep, include helper name in commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: <stable@vger.kernel.org>	# 6.3
Cc: Michael Bottini <michael.a.bottini@linux.intel.com>
Cc: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2023-11-28 09:15:08 +01:00 committed by Greg Kroah-Hartman
parent f94c44342f
commit 98bd0b4ad5
1 changed files with 1 additions and 1 deletions
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2
drivers/pci/controller/vmd.c
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@ -751,7 +751,7 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
return 0;
pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);
pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);
pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_LTR);
if (!pos)