[PATCH v2 3/3] PCI: Support PCIe Capability Slot registers only forports with slots

[Bjorn Helgaas]

Commit 6d3a1741f1e648cfbd5a0cc94477a0d5004c6f5e upstream.  This is part
of the fix for https://bugzilla.kernel.org/show_bug.cgi?id=65211

Previously we allowed callers to access Slot Capabilities, Status, and
Control for Root Ports even if the Root Port did not implement a slot.
This seems dubious because the spec only requires these registers if a
slot is implemented.

It's true that even Root Ports without slots must have *space* for these
slot registers, because the Root Capabilities, Status, and Control
registers are after the slot registers in the capability.  However,
for a v1 PCIe Capability, the *semantics* of the slot registers are
undefined unless a slot is implemented.

Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-By: Jiang Liu <jiang.liu@xxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx	# v3.7+
---
 drivers/pci/access.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 9a46fa9135d9..061da8c3ab4b 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -497,9 +497,9 @@ static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)
 {
 	int type = pci_pcie_type(dev);
 
-	return type == PCI_EXP_TYPE_ROOT_PORT ||
-	       (type == PCI_EXP_TYPE_DOWNSTREAM &&
-		pcie_caps_reg(dev) & PCI_EXP_FLAGS_SLOT);
+	return (type == PCI_EXP_TYPE_ROOT_PORT ||
+		type == PCI_EXP_TYPE_DOWNSTREAM) &&
+	       pcie_caps_reg(dev) & PCI_EXP_FLAGS_SLOT;
 }
 
 static inline bool pcie_cap_has_rtctl(const struct pci_dev *dev)

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