[PATCH 2/5] PCI/sysfs: Use user config accessors for bus number attributes

[Matthew Wood]

secondary_bus_number and subordinate_bus_number read config space with
pci_read_config_byte(). The kernel config accessors don't check
block_cfg_access, so a read that races with a reset goes to the device
mid-reset and can fail or return a bogus bus number.

Use pci_user_read_config_byte() instead, as the "config" attribute does,
so the read waits for any pci_cfg_access_lock() holder (e.g.
pci_reset_function()) to finish.

Signed-off-by: Matthew Wood <thepacketgeek@xxxxxxxxx>
Tested-by: Nikita Vetoshkin <nekto0n@xxxxxxxx>
---
 drivers/pci/pci-sysfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6669e9ad5bd3..b37a285d717d 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -267,7 +267,7 @@ static ssize_t secondary_bus_number_show(struct device *dev,
 	int err;
 
 	pci_config_pm_runtime_get(pci_dev);
-	err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);
+	err = pci_user_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);
 	pci_config_pm_runtime_put(pci_dev);
 
 	if (err)
@@ -286,7 +286,7 @@ static ssize_t subordinate_bus_number_show(struct device *dev,
 	int err;
 
 	pci_config_pm_runtime_get(pci_dev);
-	err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);
+	err = pci_user_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);
 	pci_config_pm_runtime_put(pci_dev);
 
 	if (err)
-- 
2.53.0-Meta