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Subject[PATCH 4.4 60/78] PCI: Avoid bus reset if bridge itself is broken
4.4-stable review patch.  If anyone has any objections, please let me know.


From: David Daney <>

[ 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 <>
[ fixed typo]
Signed-off-by: Jan Glauber <>
Signed-off-by: Bjorn Helgaas <>
Reviewed-by: Alex Williamson <>

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

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3850,6 +3850,10 @@ 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)))

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