From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:56640 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756005Ab2BLXvl convert rfc822-to-8bit (ORCPT ); Sun, 12 Feb 2012 18:51:41 -0500 Received: by wgbdt10 with SMTP id dt10so4352601wgb.1 for ; Sun, 12 Feb 2012 15:51:40 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1328425088-6562-1-git-send-email-yinghai@kernel.org> <1328425088-6562-5-git-send-email-yinghai@kernel.org> From: Bjorn Helgaas Date: Sun, 12 Feb 2012 15:51:20 -0800 Message-ID: Subject: Re: [PATCH 04/24] PCI: Add busn_res operation functions Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-arch-owner@vger.kernel.org List-ID: To: Yinghai Lu Cc: Jesse Barnes , Benjamin Herrenschmidt , Tony Luck , Dominik Brodowski , Andrew Morton , Linus Torvalds , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Message-ID: <20120212235120.rtD_3gRbbBGThEA86Lvny8sXXdAW01xt7PHGdQi1j6k@z> On Mon, Feb 6, 2012 at 12:45 PM, Yinghai Lu wrote: > On Mon, Feb 6, 2012 at 10:59 AM, Bjorn Helgaas wrote: >> On Sat, Feb 4, 2012 at 10:57 PM, Yinghai Lu wrote: >>> will use them insert/update busn res in pci_bus >>> >>> Signed-off-by: Yinghai Lu >>> --- >>>  drivers/pci/probe.c |   42 ++++++++++++++++++++++++++++++++++++++++++ >>>  include/linux/pci.h |    3 +++ >>>  2 files changed, 45 insertions(+), 0 deletions(-) >>> >>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >>> index a114173..8d4de5e 100644 >>> --- a/drivers/pci/probe.c >>> +++ b/drivers/pci/probe.c >>> @@ -1622,6 +1622,48 @@ err_out: >>>        return NULL; >>>  } >>> >>> +void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max) >>> +{ >>> +       struct resource *res = &b->busn_res; >>> +       struct resource *parent_res = &iobusn_resource; >>> +       int ret; >>> + >>> +       res->start = busn(pci_domain_nr(b), bus); >>> +       res->end = busn(pci_domain_nr(b), bus_max); >>> +       res->flags = IORESOURCE_BUS; >>> + >>> +       if (!pci_is_root_bus(b)) >>> +               parent_res = &b->parent->busn_res; >>> + >>> +       ret = insert_resource(parent_res, res); >>> + >>> +       dev_printk(KERN_DEBUG, &b->dev, >>> +                       "busn_res: %pR %s inserted under %pR\n", >>> +                       res, ret ? "can not be" : "is", parent_res); >>> +} >>> + >>> +void pci_bus_update_busn_res_end(struct pci_bus *b, int bus_max) >>> +{ >>> +       struct resource *res = &b->busn_res; >>> +       struct resource old_res = *res; >>> + >>> +       res->end = busn_update_bus_nr(res->end, bus_max); >> >> I think this design is a mistake.  Here's what you're doing: >> >>  - initialize struct resource (keys are "start" and "end") >>  - insert into tree (placed in tree by kernel/resource.c based on >> "start" and "end") >>  - update "end" >> >> You "know" in this case that the update is safe because the caller has >> validated "bus_max."  But that still breaks the kernel/resource.c >> encapsulation.  If we change the kernel/resource.c implementation, >> this code might break. > > the point is: I only want to reuse allocate_resource() to get right position. > and the code does not depends to kernel/resource.c much. > >> >> I think it would be better to remove the bus resource from the tree, >> change its "end," then re-insert it. > > how about parent buses that have extended top? I don't understand your question. I assume you mean there's a case where remove/update/reinsert doesn't work, but I don't see why that would be a problem. Can you show an example?