[PATCH 3.18 31/38] PCI: Avoid bus reset if bridge itself is broken

From: Greg Kroah-Hartman
Date: Fri Dec 22 2017 - 03:49:03 EST

3.18-stable review patch. If anyone has any objections, please let me know.


From: David Daney <david.daney@xxxxxxxxxx>

[ Upstream commit 357027786f3523d26f42391aa4c075b8495e5d28 ]

When checking to see if a PCI bus can safely be reset, we previously
checked to see if any of the children had their PCI_DEV_FLAGS_NO_BUS_RESET
flag set. Children marked with that flag are known not to behave well
after a bus reset.

Some PCIe root port bridges also do not behave well after a bus reset,
sometimes causing the devices behind the bridge to become unusable.

Add a check for PCI_DEV_FLAGS_NO_BUS_RESET being set in the bridge device
to allow these bridges to be flagged, and prevent their secondary buses
from being reset.

Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
[jglauber@xxxxxxxxxx: fixed typo]
Signed-off-by: Jan Glauber <jglauber@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Alex Williamson <alex.williamson@xxxxxxxxxx>

Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/pci/pci.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3580,6 +3580,10 @@ static bool pci_bus_resetable(struct pci
struct pci_dev *dev;

+ if (bus->self && (bus->self->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET))
+ return false;
list_for_each_entry(dev, &bus->devices, bus_list) {
if (dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||
(dev->subordinate && !pci_bus_resetable(dev->subordinate)))