From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: "Rafael J. Wysocki" To: Alex Williamson Cc: ACPI Devel Maling List , Bjorn Helgaas , LKML , Linux PCI , Yinghai Lu , Jiang Liu , Mika Westerberg , "Kirill A. Shutemov" Subject: [PATCH 1/2] ACPI / hotplug / PCI: Avoid doing too much for spurious notifies Date: Fri, 06 Sep 2013 15:43:52 +0200 Message-ID: <1831138.AvDtjG8RWn@vostro.rjw.lan> In-Reply-To: <2228690.GcUDD3xFfP@vostro.rjw.lan> References: <26431283.HJCKsss0rt@vostro.rjw.lan> <1599165.8kjc3DtEzc@vostro.rjw.lan> <2228690.GcUDD3xFfP@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-acpi-owner@vger.kernel.org List-ID: From: Rafael J. Wysocki 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 ports during boot. Reported-by: Alex Williamson Signed-off-by: Rafael J. Wysocki --- drivers/pci/hotplug/acpiphp_glue.c | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-) Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c =================================================================== --- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c +++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c @@ -542,12 +542,12 @@ static void __ref enable_slot(struct acp 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 acp } } } - __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);