Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753083Ab3GWBTC (ORCPT ); Mon, 22 Jul 2013 21:19:02 -0400 Received: from mail-ie0-f169.google.com ([209.85.223.169]:54205 "EHLO mail-ie0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751296Ab3GWBS7 (ORCPT ); Mon, 22 Jul 2013 21:18:59 -0400 MIME-Version: 1.0 In-Reply-To: References: <1372860295-8306-1-git-send-email-mika.westerberg@linux.intel.com> <1372860295-8306-2-git-send-email-mika.westerberg@linux.intel.com> From: Bjorn Helgaas Date: Mon, 22 Jul 2013 19:18:38 -0600 Message-ID: Subject: Re: [PATCH v2 1/8] x86/PCI: prevent re-allocation of already existing bridge and ROM resources To: Mika Westerberg Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Jesse Barnes , Yinghai Lu , "Ronciak, John" , "Penner, Miles J" , Bruce Allan , Heikki Krogerus , "Kirill A. Shutemov" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-pci@vger.kernel.org" , "x86@kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3219 Lines: 75 On Mon, Jul 22, 2013 at 6:08 PM, Bjorn Helgaas wrote: > On Wed, Jul 3, 2013 at 8:04 AM, Mika Westerberg > wrote: >> In hotplug case (especially with Thunderbolt enabled systems) we might need >> to call pcibios_resource_survey_bus() several times for a bus. The function >> ends up calling pci_claim_resource() for each bridge resource that then >> fails claiming that the resource exists already (which it does). Once this >> happens the resource is invalidated thus preventing devices behind the >> bridge to allocate their resources. >> >> To fix this we do what has been done in pcibios_allocate_dev_resources() >> and check 'parent' of the given resource. If it is non-NULL it means that >> the resource has been allocated already and we can skip it. We do the same >> for ROM resources as well. >> >> Signed-off-by: Mika Westerberg > > This looks reasonable to me. Acked-by: Bjorn Helgaas > However, the use of "r->parent" to determine whether the resource is > already allocated is nothing specific to x86. So I think we might be > missing an opportunity to make this more consistent across > architectures. I looked at other callers of pci_claim_resource() for > bridge and ROM resources, and it looks like we might be able to make > similar changes in: > > frv pcibios_allocate_bus_resources() > ia64 pcibios_fixup_resources() (via pcibios_fixup_bridge_resources()) > mn10300 pcibios_allocate_bus_resources() > mn10300 pcibios_assign_resources() (ROM) > mn10300 pcibios_fixup_device_resources() > parisc lba_fixup_bus() > > I really hate the idea of fixing something for x86 but not for other > arches, so maybe somebody could take a deeper look at this and see if > it would make sense to change the other arches, too. > > Bjorn > >> --- >> arch/x86/pci/i386.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c >> index 94919e3..db6b1ab 100644 >> --- a/arch/x86/pci/i386.c >> +++ b/arch/x86/pci/i386.c >> @@ -210,6 +210,8 @@ static void pcibios_allocate_bridge_resources(struct pci_dev *dev) >> r = &dev->resource[idx]; >> if (!r->flags) >> continue; >> + if (r->parent) /* Already allocated */ >> + continue; >> if (!r->start || pci_claim_resource(dev, idx) < 0) { >> /* >> * Something is wrong with the region. >> @@ -318,6 +320,8 @@ static void pcibios_allocate_dev_rom_resource(struct pci_dev *dev) >> r = &dev->resource[PCI_ROM_RESOURCE]; >> if (!r->flags || !r->start) >> return; >> + if (r->parent) /* Already allocated */ >> + return; >> >> if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) { >> r->end -= r->start; >> -- >> 1.8.3.2 >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/