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PCI: Check for PCI_HEADER_TYPE_BRIDGE equality, not bitmask

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Bit 7 of the "Header Type" register indicates a multi-function device when
set.  Bits 0-6 contain encoded values, where 0x1 indicates a PCI-PCI
bridge.  It is incorrect to test this as though it were a mask.

For example, while the PCI 3.0 spec only defines values 0x0, 0x1, and 0x2,
it's conceivable that a future spec could define 0x3 to mean something
else; then tests for "(hdr_type & 0x7f) & PCI_HEADER_TYPE_BRIDGE" would
incorrectly succeed for this new 0x3 header type.

Test bits 0-6 of the Header Type for equality with PCI_HEADER_TYPE_BRIDGE.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Bjorn Helgaas 2015-12-03 13:18:18 -06:00
parent 1ec218373b
commit 93de690176
3 changed files with 7 additions and 7 deletions
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2
drivers/pci/hotplug/ibmphp_pci.c
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@ -1119,7 +1119,7 @@ static struct res_needed *scan_behind_bridge (struct pci_func *func, u8 busno)
pci_bus_read_config_dword (ibmphp_pci_bus, devfn, PCI_CLASS_REVISION, &class);
debug ("hdr_type behind the bridge is %x\n", hdr_type);
if (hdr_type & PCI_HEADER_TYPE_BRIDGE) {
if ((hdr_type & 0x7f) == PCI_HEADER_TYPE_BRIDGE) {
err ("embedded bridges not supported for hot-plugging.\n");
amount->not_correct = 1;
return amount;