From: Brian Norris <briannorris@google.com>
Date: Mon, 20 Oct 2025 20:41:36 +0000 (-0700)
Subject: PCI/sysfs: Ensure devices are powered for config reads (part 2)
X-Git-Tag: v5.15.196~79
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ae9ad3b6732528cfd60f7b86b77d8d8bc4662b9e;p=thirdparty%2Fkernel%2Fstable.git

PCI/sysfs: Ensure devices are powered for config reads (part 2)

Commit 48991e493507 ("PCI/sysfs: Ensure devices are powered for config
reads") was applied to various linux-stable trees. However, prior to
6.12.y, we do not have commit d2bd39c0456b ("PCI: Store all PCIe
Supported Link Speeds"). Therefore, we also need to apply the change to
max_link_speed_show().

This was pointed out here:

  Re: Patch "PCI/sysfs: Ensure devices are powered for config reads" has been added to the 6.6-stable tree
  https://lore.kernel.org/all/aPEMIreBYZ7yk3cm@google.com/

Original change description follows:

    The "max_link_width", "current_link_speed", "current_link_width",
    "secondary_bus_number", and "subordinate_bus_number" sysfs files all access
    config registers, but they don't check the runtime PM state. If the device
    is in D3cold or a parent bridge is suspended, we may see -EINVAL, bogus
    values, or worse, depending on implementation details.

    Wrap these access in pci_config_pm_runtime_{get,put}() like most of the
    rest of the similar sysfs attributes.

    Notably, "max_link_speed" does not access config registers; it returns a
    cached value since d2bd39c0456b ("PCI: Store all PCIe Supported Link
    Speeds").

Fixes: 56c1af4606f0 ("PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc")
Link: https://lore.kernel.org/all/aPEMIreBYZ7yk3cm@google.com/
Signed-off-by: Brian Norris <briannorris@google.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5f86f49ad3c8..2943c4ca5c08 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -164,9 +164,15 @@ static ssize_t max_link_speed_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
+	ssize_t ret;
+
+	/* We read PCI_EXP_LNKCAP, so we need the device to be accessible. */
+	pci_config_pm_runtime_get(pdev);
+	ret = sysfs_emit(buf, "%s\n",
+			 pci_speed_string(pcie_get_speed_cap(pdev)));
+	pci_config_pm_runtime_put(pdev);
 
-	return sysfs_emit(buf, "%s\n",
-			  pci_speed_string(pcie_get_speed_cap(pdev)));
+	return ret;
 }
 static DEVICE_ATTR_RO(max_link_speed);