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

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Message-ID: <20231114135553.32301-3-johan+linaro@kernel.org>
Date:   Tue, 14 Nov 2023 14:55:49 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     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,
        Johan Hovold <johan+linaro@...nel.org>, stable@...r.kernel.org,
        Michael Bottini <michael.a.bottini@...ux.intel.com>,
        "David E . Box" <david.e.box@...ux.intel.com>
Subject: [PATCH 2/6] PCI: vmd: Fix deadlock when enabling ASPM

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@...r.kernel.org      # 6.3
Cc: Michael Bottini <michael.a.bottini@...ux.intel.com>
Cc: David E. Box <david.e.box@...ux.intel.com>
Signed-off-by: Johan Hovold <johan+linaro@...nel.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