Commit 8066cc86 authored by Mika Westerberg's avatar Mika Westerberg Committed by Bjorn Helgaas
Browse files

PCI: Fix used_buses calculation in pci_scan_child_bus_extend() 

pci_scan_bridge_extend() returns the subordinate bus number needed to cover
all the buses below a bridge.  pci_scan_child_bus_extend() computes the
number of buses to reserve by comparing that with the current max bus
number.  Previously it did the subtraction in the wrong order, so
'used_buses' was nonsense.

Subtract 'max' from 'cmax' as is done for the similar
pci_scan_bridge_extend() call in the following block.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216000
Fixes: 3374c545 ("PCI: Account for all bridges on bus when distributing bus numbers")
Link: https://lore.kernel.org/r/20220905080232.36087-2-mika.westerberg@linux.intel.com


Reported-by: default avatarChris Chiu <chris.chiu@canonical.com>
Tested-by: default avatarChris Chiu <chris.chiu@canonical.com>
Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
parent 568035b0

drivers/pci/probe.c

+2 −2
Original line number Diff line number Diff line
@@ -2920,8 +2920,8 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, 
		 * hotplug bridges too much during the second scan below.

		 */

		used_buses++;

		if (cmax - max > 1)

			used_buses += cmax - max - 1;

		if (max - cmax > 1)

			used_buses += max - cmax - 1;

	}



	/* Scan bridges that need to be reconfigured */