Hi Hannes,

On Wed, Jan 13, 2016 at 12:25:33PM +0100, Hannes Reinecke wrote:
> It is not always possible to determine the actual size of the VPD
> data, so allow access to them if the size is set to '0'.
> 
> Signed-off-by: Hannes Reinecke <h...@suse.de>
> ---
>  drivers/pci/pci-sysfs.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index eead54c..de327c3 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -772,10 +772,12 @@ static ssize_t read_vpd_attr(struct file *filp, struct 
> kobject *kobj,
>       struct pci_dev *dev =
>               to_pci_dev(container_of(kobj, struct device, kobj));
>  
> -     if (off > bin_attr->size)
> -             count = 0;
> -     else if (count > bin_attr->size - off)
> -             count = bin_attr->size - off;
> +     if (bin_attr->size > 0) {
> +             if (off > bin_attr->size)
> +                     count = 0;
> +             else if (count > bin_attr->size - off)
> +                     count = bin_attr->size - off;
> +     }

I'm trying to figure out why we do any of this checking here.  It
seems like we could do all of it in pci_read_vpd().

Where is bin_attr->size set?  I assume this is the "attr" allocated in
pci_create_capabilities_sysfs().  I see that before your series, we
set "attr->size = dev->vpd->len" there, but after patch 3/4 of your
series, we set it to 0 there, and I don't see a place that sets it to
anything else.

>       return pci_read_vpd(dev, off, count, buf);
>  }
> @@ -787,10 +789,12 @@ static ssize_t write_vpd_attr(struct file *filp, struct 
> kobject *kobj,
>       struct pci_dev *dev =
>               to_pci_dev(container_of(kobj, struct device, kobj));
>  
> -     if (off > bin_attr->size)
> -             count = 0;
> -     else if (count > bin_attr->size - off)
> -             count = bin_attr->size - off;
> +     if (bin_attr->size > 0) {
> +             if (off > bin_attr->size)
> +                     count = 0;
> +             else if (count > bin_attr->size - off)
> +                     count = bin_attr->size - off;
> +     }
>  
>       return pci_write_vpd(dev, off, count, buf);
>  }
> -- 
> 1.8.5.6
> 
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