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SubjectRe: [PATCHv2 2/4] pci: allow access to VPD attributes with size '0'
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 <hare@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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