On 2019-05-17, at 13:54:51 +0200, Greg KH wrote:
> On Fri, May 17, 2019 at 12:03:12PM +0100, Jeremy Sowden wrote:
> > The call-backs used the same recipe to get the pcard from dev:
> >
> > struct pci_dev *pdev = to_pci_dev(dev);
> > struct kp2000_device *pcard;
> >
> > if (!pdev) return -ENXIO;
> > pcard = pci_get_drvdata(pdev);
> > if (!pcard) return -ENXIO;
> >
> > where to_pci_dev is a wrapper for container_of.
> >
> > However, pci_set_drvdata is called before the sysfs files are
> > created:
> >
> > int kp2000_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > {
> > // ...
> >
> > pcard = kzalloc(sizeof(struct kp2000_device), GFP_KERNEL);
> >
> > // ...
> >
> > pcard->pdev = pdev;
> > pci_set_drvdata(pdev, pcard);
> >
> > // ...
> >
> > err = sysfs_create_files(&(pdev->dev.kobj), kp_attr_list);
> >
> > Therefore, to_pci_dev and pci_get_drvdata cannot return NULL, and
> > pcard can be initialized directly from dev:
> >
> > struct kp2000_device *pcard = dev_get_drvdata(dev);
> >
> > Signed-off-by: Jeremy Sowden <jeremy@xxxxxxxxxx>
> > ---
> > drivers/staging/kpc2000/kpc2000/core.c | 24 +++---------------------
> > 1 file changed, 3 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/staging/kpc2000/kpc2000/core.c b/drivers/staging/kpc2000/kpc2000/core.c
> > index eb8bac62d33d..9425c4dbc2f2 100644
> > --- a/drivers/staging/kpc2000/kpc2000/core.c
> > +++ b/drivers/staging/kpc2000/kpc2000/core.c
> > @@ -24,12 +24,7 @@
> > ******************************************************/
> > static ssize_t show_attr(struct device *dev, struct device_attribute *attr, char *buf)
> > {
> > - struct pci_dev *pdev = to_pci_dev(dev);
> > - struct kp2000_device *pcard;
> > -
> > - if (!pdev) return -ENXIO;
> > - pcard = pci_get_drvdata(pdev);
> > - if (!pcard) return -ENXIO;
> > + struct kp2000_device *pcard = dev_get_drvdata(dev);
>
> Wait, dev_get_drvdata() is not returning you the same pointer that
> pci_get_drvdata() does. So I think this is now broken :(
I'm confused. Perhaps I'm looking at the wrong code.
Here are pci_get_drvdata:
static inline void *pci_get_drvdata(struct pci_dev *pdev)
{
return dev_get_drvdata(&pdev->dev);
}
and dev_get_drvdata:
static inline void *dev_get_drvdata(const struct device *dev)
{
return dev->driver_data;
}
Starting withing with dev and using to_pci_dev, we have:
pci_get_drvdata(to_pci_dev(dev))
which is the same as:
dev_get_drvdata(&(to_pci_dev(dev)->dev)
which is the same as:
dev_get_drvdata(dev)
isn't it?
> What this should look like is this:
> struct pci_dev *pdev = to_pci_dev(dev);
> struct kp200_device *pcard = pci_get_drvdata(pdev);
>
> if (!pcard)
> return -ENODEV;
>
> that is IF the driver really is setting the pci dev data to NULL when
> the device is removed from the driver. Is it?
It sets it to NULL after removing the sysfs files and disabling the
device:
lock_card(pcard);
// ...
sysfs_remove_files(&(pdev->dev.kobj), kp_attr_list);
// ...
pci_disable_device(pcard->pdev);
pci_set_drvdata(pdev, NULL);
unlock_card(pcard);
kfree(pcard);
Can the show functions get called after pci_set_drvdata is called?
J.
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