From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
If "hotplug_bridges == 0", "!dev->is_hotplug_bridge" is always true, so the
loop that divides the remaining resources among hotplug-capable bridges
does nothing.
Check for "hotplug_bridges == 0" earlier, so we don't even have to compute
the amount of remaining resources. No functional change intended.
---
I'm pretty sure this patch preserves the previous behavior of
pci_bus_distribute_available_resources(), but I'm not sure that
behavior is what we want.
For example, in the following topology, when we process bus 10, we
find two non-hotplug bridges and no hotplug bridges, so IIUC we return
without distributing any resources to them. But I would think we
should try to give 10:1c.0 more space if possible because it has a
hotplug bridge below it.
00:1c.0: hotplug bridge to [bus 10-2f]
10:1c.0: non-hotplug bridge to [bus 11-2e]
11:00.0: hotplug bridge to [bus 12-2e]
10:1c.1: non-hotplug bridge to [bus 2f]
---
drivers/pci/setup-bus.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index af28af898e42..04adeebe8866 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1887,6 +1887,9 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
return;
}
+ if (hotplug_bridges == 0)
+ return;
+
/*
* Calculate the total amount of extra resource space we can
* pass to bridges below this one. This is basically the
@@ -1936,8 +1939,6 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
* Distribute available extra resources equally between
* hotplug-capable downstream ports taking alignment into
* account.
- *
- * Here hotplug_bridges is always != 0.
*/
align = pci_resource_alignment(bridge, io_res);
io = div64_ul(available_io, hotplug_bridges);
--
2.22.0.410.gd8fdbe21b5-goog
