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From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 20 Aug 2018 13:16:55 +0200
Message-ID: <CAK8P3a1KWn0=xwrqZ+sF27O-WE6paDxQPg6PPZFcgCrgXGaX2A@mail.gmail.com>
Subject: Re: [RFC 08/15] x86: PCI: clean up pcibios_scan_root()
To: Rafael Wysocki <rafael@kernel.org>
Cc: linux-pci <linux-pci@vger.kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
 Christoph Hellwig <hch@infradead.org>,
 Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
 ACPI Devel Maling List <linux-acpi@vger.kernel.org>
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On Mon, Aug 20, 2018 at 10:31 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Fri, Aug 17, 2018 at 12:32 PM Arnd Bergmann <arnd@arndb.de> wrote:

> > -static struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> > -               struct pci_ops *ops, void *sysdata, struct list_head *resources)
> > +void pcibios_scan_root(int busnum)
> >  {
> > +       struct pci_sysdata *sd;
> >         struct pci_host_bridge *bridge;
> >         int error;
> >
> > -       bridge = pci_alloc_host_bridge(0);
> > -       if (!bridge)
> > -               return NULL;
> > +       bridge = pci_alloc_host_bridge(sizeof(sd));
> > +       if (!bridge) {
> > +               printk(KERN_ERR "PCI: OOM, skipping PCI bus %02x\n", busnum);
> > +               return;
> > +       }
> > +       sd = pci_host_bridge_priv(bridge);
>
> This looks fishy, as bridge->private is not set at this point AFAICS,
> unless one of the previous patches changes that.

bridge->private what comes after the bridge structure, and it's allocated
by pci_alloc_host_bridge() passing the size of the structure we want
for this private area.

         Arnd