[+cc Alex, FYI]
On Thu, Jun 03, 2021 at 12:01:11AM +0000, Krzysztof Wilczyński wrote:
> Only expose the value of the "driver_override" variable through the
> corresponding sysfs object when a value is actually set.
This changes the attribute contents from "(null)" to an empty
(zero-length) file when no driver override has been set.
There are a few other driver_override_show() functions. Most don't
check the pointer so they'll show "(null)". One (spi.c) checks and
shows an empty string ("", file containing a single NULL character)
instead of an empty (zero-length) file.
> Signed-off-by: Krzysztof Wilczyński <kw@xxxxxxxxx>
> Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> ---
> drivers/pci/pci-sysfs.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 5d63df7c1820..4e9f582ca10f 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -580,10 +580,11 @@ static ssize_t driver_override_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct pci_dev *pdev = to_pci_dev(dev);
> - ssize_t len;
> + ssize_t len = 0;
>
> device_lock(dev);
> - len = sysfs_emit(buf, "%s\n", pdev->driver_override);
> + if (pdev->driver_override)
> + len = sysfs_emit(buf, "%s\n", pdev->driver_override);
> device_unlock(dev);
> return len;
> }
> --
> 2.31.1
>
