On Mon, 1 Jul 2019 22:43:10 +0530
Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
> On 7/1/2019 8:24 PM, Alex Williamson wrote:
> > This allows udev to trigger rules when a parent device is registered
> > or unregistered from mdev.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > ---
> >
> > v2: Don't remove the dev_info(), Kirti requested they stay and
> > removing them is only tangential to the goal of this change.
> >
>
> Thanks.
>
>
> > drivers/vfio/mdev/mdev_core.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> > index ae23151442cb..7fb268136c62 100644
> > --- a/drivers/vfio/mdev/mdev_core.c
> > +++ b/drivers/vfio/mdev/mdev_core.c
> > @@ -146,6 +146,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
> > {
> > int ret;
> > struct mdev_parent *parent;
> > + char *env_string = "MDEV_STATE=registered";
> > + char *envp[] = { env_string, NULL };
> >
> > /* check for mandatory ops */
> > if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups)
> > @@ -197,6 +199,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
> > mutex_unlock(&parent_list_lock);
> >
> > dev_info(dev, "MDEV: Registered\n");
> > + kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
> > +
> > return 0;
> >
> > add_dev_err:
> > @@ -220,6 +224,8 @@ EXPORT_SYMBOL(mdev_register_device);
> > void mdev_unregister_device(struct device *dev)
> > {
> > struct mdev_parent *parent;
> > + char *env_string = "MDEV_STATE=unregistered";
> > + char *envp[] = { env_string, NULL };
> >
> > mutex_lock(&parent_list_lock);
> > parent = __find_parent_device(dev);
> > @@ -243,6 +249,8 @@ void mdev_unregister_device(struct device *dev)
> > up_write(&parent->unreg_sem);
> >
> > mdev_put_parent(parent);
> > +
> > + kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
>
> mdev_put_parent() calls put_device(dev). If this is the last instance
> holding device, then on put_device(dev) dev would get freed.
>
> This event should be before mdev_put_parent()
So you're suggesting the vendor driver is calling
mdev_unregister_device() without a reference to the struct device that
it's passing to unregister? Sounds bogus to me. We take a
reference to the device so that it can't disappear out from under us,
the caller cannot rely on our reference and the caller provided the
struct device. Thanks,
Alex
