linux-kernel - [PATCH v4 3/3] PCI: Avoid slot reset if bus reset is not possible

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Message-Id: <20170908081033.3025-4-jglauber@cavium.com>
Date:   Fri,  8 Sep 2017 10:10:33 +0200
From:   Jan Glauber <jglauber@...ium.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        linux-kernel@...r.kernel.org, david.daney@...ium.com,
        Jon Masters <jcm@...hat.com>,
        Robert Richter <robert.richter@...ium.com>,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        Jan Glauber <jglauber@...ium.com>
Subject: [PATCH v4 3/3] PCI: Avoid slot reset if bus reset is not possible

When checking to see if a PCI slot can safely be reset, we check to
see if any of the children have 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 the PCI_DEV_FLAGS_NO_BUS_RESET flag being set in the
bridge device to prevent the slot from being reset.

Signed-off-by: Jan Glauber <jglauber@...ium.com>
---
 drivers/pci/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b2a46ca7f133..45a086fc3592 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4393,6 +4393,10 @@ 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)
 			continue;
-- 
2.9.0.rc0.21.g7777322