linux-kernel - Re: [PATCH 10/13] PCI: Strict checking of valid range for bridge

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Date:	Mon, 30 Jan 2012 08:04:39 -0800
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Tony Luck <tony.luck@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH 10/13] PCI: Strict checking of valid range for bridge

On Fri, Jan 27, 2012 at 6:49 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> children bridges busn range should be able to be allocated from parent bus range.
>
> to avoid overlapping between sibling bridges on same bus.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  drivers/pci/probe.c |   27 +++++++++++++++++++++++++++
>  1 files changed, 27 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 83df3fb..e12f65f0 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -791,6 +791,33 @@ reduce_needed_size:
>        return ret;
>  }
>
> +static int __devinit pci_bridge_check_busn_res(struct pci_bus *bus,
> +                               struct pci_dev *dev,
> +                               int secondary, int subordinate)

This function returns a boolean, but the function name doesn't give
any clue about what a true/false return means.  Something like
"busn_valid" would make the callers more readable.

> +{
> +       int broken = 0;
> +
> +       struct resource busn_res;
> +       int ret;
> +
> +       memset(&busn_res, 0, sizeof(struct resource));
> +       dev_printk(KERN_DEBUG, &dev->dev,
> +                "check if busn %02x-%02x is in busn_res: %06llx-%06llx\n",
> +                secondary, subordinate,
> +                (unsigned long long)bus->busn_res.start,
> +                (unsigned long long)bus->busn_res.end);
> +       ret = allocate_resource(&bus->busn_res, &busn_res,
> +                        (subordinate - secondary + 1),
> +                        (pci_domain_nr(bus)<<8) | secondary,
> +                        (pci_domain_nr(bus)<<8) | subordinate,

I think this "(pci_domain_nr(bus)<<8) | secondary" stuff needs to be a
macro or something.

> +                        1, NULL, NULL);
> +       if (ret)
> +               broken = 1;
> +       else
> +               release_resource(&busn_res);
> +
> +       return broken;
> +}
>  /*
>  * If it's a bridge, configure it and scan the bus behind it.
>  * For CardBus bridges, we don't scan behind as the devices will
> --
> 1.7.7
>
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