[PATCH 2/6] PCI: vmd: Fix deadlock when enabling ASPM

Johan Hovold
2023-11-14T13:56:58Z

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 the new
locked helper 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: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR")
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: Johan Hovold <johan+linaro@kernel.org>
---
drivers/pci/controller/vmd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 94ba61fe1c44..0452cbc362ee 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -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)
--
2.41.0