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PCI/sysfs: Ensure devices are powered for config reads

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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 d2bd39c045 ("PCI: Store all PCIe Supported Link
Speeds").

Fixes: 56c1af4606 ("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
This commit is contained in:
Brian Norris 2025-09-24 09:57:11 -07:00 committed by Bjorn Helgaas
parent 299fad4133
commit 48991e4935
1 changed files with 19 additions and 1 deletions
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20
drivers/pci/pci-sysfs.c
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@ -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;