FAILED: patch "[PATCH] PCI/sysfs: Ensure devices are powered for config reads" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] PCI/sysfs: Ensure devices are powered for config reads" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 48991e4935078b05f80616c75d1ee2ea3ae18e58
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101641-squire-emboss-834e@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 48991e4935078b05f80616c75d1ee2ea3ae18e58 Mon Sep 17 00:00:00 2001
From: Brian Norris <briannorris@google.com>
Date: Wed, 24 Sep 2025 09:57:11 -0700
Subject: [PATCH] PCI/sysfs: Ensure devices are powered for config reads

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")
Signed-off-by: Brian Norris <briannorris@google.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250924095711.v2.1.Ibb5b6ca1e2c059e04ec53140cd98a44f2684c668@changeid

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5eea14c1f7f5..2b231ef1dac9 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -201,8 +201,14 @@ static ssize_t max_link_width_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
+	ssize_t ret;
 
-	return sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev));
+	/* We read PCI_EXP_LNKCAP, so we need the device to be accessible. */
+	pci_config_pm_runtime_get(pdev);
+	ret = sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev));
+	pci_config_pm_runtime_put(pdev);
+
+	return ret;
 }
 static DEVICE_ATTR_RO(max_link_width);
 
@@ -214,7 +220,10 @@ static ssize_t current_link_speed_show(struct device *dev,
 	int err;
 	enum pci_bus_speed speed;
 
+	pci_config_pm_runtime_get(pci_dev);
 	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
+	pci_config_pm_runtime_put(pci_dev);
+
 	if (err)
 		return -EINVAL;
 
@@ -231,7 +240,10 @@ static ssize_t current_link_width_show(struct device *dev,
 	u16 linkstat;
 	int err;
 
+	pci_config_pm_runtime_get(pci_dev);
 	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
+	pci_config_pm_runtime_put(pci_dev);
+
 	if (err)
 		return -EINVAL;
 
@@ -247,7 +259,10 @@ static ssize_t secondary_bus_number_show(struct device *dev,
 	u8 sec_bus;
 	int err;
 
+	pci_config_pm_runtime_get(pci_dev);
 	err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);
+	pci_config_pm_runtime_put(pci_dev);
+
 	if (err)
 		return -EINVAL;
 
@@ -263,7 +278,10 @@ static ssize_t subordinate_bus_number_show(struct device *dev,
 	u8 sub_bus;
 	int err;
 
+	pci_config_pm_runtime_get(pci_dev);
 	err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);
+	pci_config_pm_runtime_put(pci_dev);
+
 	if (err)
 		return -EINVAL;