On 2019-06-22 3:03 p.m., Bjorn Helgaas wrote: > 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. Makes sense. Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> > --- > > 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); >
