[PATCH 3/3] PCI: Avoid slot reset if bridge itself is broken

Manoj Iyer manoj.iyer at canonical.com
Thu May 10 19:32:54 UTC 2018

From: Jan Glauber <jglauber at cavium.com>

When checking to see if a PCI slot can safely be reset, we previously
checked to see if any of the children had their PCI_DEV_FLAGS_NO_BUS_RESET
flag set.

Some PCIe root port bridges do not behave well after a slot reset, and may
cause the device in the slot to become unusable.

Add a check for PCI_DEV_FLAGS_NO_BUS_RESET being set in the bridge device
to prevent the slot from being reset.

BugLink: https://launchpad.net/bugs/1770254

Signed-off-by: Jan Glauber <jglauber at cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Reviewed-by: Alex Williamson <alex.williamson at redhat.com>
(cherry picked from commit 33ba90aa4d4432b884fc0ed57ba9dc12eb8fa288)
Signed-off-by: Manoj Iyer <manoj.iyer at canonical.com>
 drivers/pci/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2cce730f8ce9..0ce61a52788c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4430,6 +4430,10 @@ static bool pci_slot_resetable(struct pci_slot *slot)
 	struct pci_dev *dev;
+	if (slot->bus->self &&
+	    (slot->bus->self->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET))
+		return false;
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
 		if (!dev->slot || dev->slot != slot)

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