On Thu, 3 Jun 2021 18:23:34 -0500
Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> [+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.
Yeah, "(null)" was the expected output in this case. It looks like
this might break driverctl. Thanks,
Alex
> > 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
> >
>
