From: Rafael J. Wysocki Date: Fri, 6 Sep 2013 13:41:32 +0000 (+0200) Subject: ACPI / hotplug / PCI: Avoid doing too much for spurious notifies X-Git-Tag: MMI-PSA29.97-13-9~13630^2~6^2~2 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2dc4128;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git ACPI / hotplug / PCI: Avoid doing too much for spurious notifies Sometimes we may get a spurious device check or bus check notify for a hotplug device and in those cases we should avoid doing all of the configuration work needed when something actually changes. To that end, check the return value of pci_scan_slot() in enable_slot() and bail out early if it is 0. This turns out to help reduce the amount of diagnostic output from the ACPIPHP subsystem and speed up boot on at least one system that generates multiple device check notifies for PCIe devices on the root bus during boot. Reported-and-tested-by: Alex Williamson Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 3f78212f4eee..65290226e5dd 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -542,12 +542,12 @@ static void __ref enable_slot(struct acpiphp_slot *slot) struct acpiphp_func *func; int max, pass; LIST_HEAD(add_list); + int nr_found; list_for_each_entry(func, &slot->funcs, sibling) acpiphp_bus_add(func_to_handle(func)); - pci_scan_slot(bus, PCI_DEVFN(slot->device, 0)); - + nr_found = pci_scan_slot(bus, PCI_DEVFN(slot->device, 0)); max = acpiphp_max_busnr(bus); for (pass = 0; pass < 2; pass++) { list_for_each_entry(dev, &bus->devices, bus_list) { @@ -566,8 +566,11 @@ static void __ref enable_slot(struct acpiphp_slot *slot) } } } - __pci_bus_assign_resources(bus, &add_list, NULL); + /* Nothing more to do here if there are no new devices on this bus. */ + if (!nr_found && (slot->flags & SLOT_ENABLED)) + return; + acpiphp_sanitize_bus(bus); acpiphp_set_hpp_values(bus); acpiphp_set_acpi_region(slot);