On Sun, Sep 09, 2018 at 09:11:46PM +0300, Arseny Maslennikov wrote: > On Fri, Sep 07, 2018 at 09:43:59AM -0600, Jason Gunthorpe wrote: > > On Thu, Sep 06, 2018 at 05:51:12PM +0300, Arseny Maslennikov wrote: > > > Some tools may currently be using only the deprecated attribute; > > > let's print an elaborate and clear deprecation notice to kmsg. > > > > > > To do that, we have to replace the whole sysfs file, since we inherit > > > the original one from netdev. > > > > > > Signed-off-by: Arseny Maslennikov <a...@cs.msu.ru> > > > drivers/infiniband/ulp/ipoib/ipoib_main.c | 31 +++++++++++++++++++++++ > > > 1 file changed, 31 insertions(+) > > > > > > diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c > > > b/drivers/infiniband/ulp/ipoib/ipoib_main.c > > > index 30f840f874b3..74732726ec6f 100644 > > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c > > > @@ -2386,6 +2386,35 @@ int ipoib_add_pkey_attr(struct net_device *dev) > > > return device_create_file(&dev->dev, &dev_attr_pkey); > > > } > > > > > > +/* > > > + * We erroneously exposed the iface's port number in the dev_id > > > + * sysfs field long after dev_port was introduced for that purpose[1], > > > + * and we need to stop everyone from relying on that. > > > + * Let's overload the shower routine for the dev_id file here > > > + * to gently bring the issue up. > > > + * > > > + * [1] https://www.spinics.net/lists/netdev/msg272123.html > > > + */ > > > +static ssize_t dev_id_show(struct device *dev, > > > + struct device_attribute *attr, char *buf) > > > +{ > > > + struct net_device *ndev = to_net_dev(dev); > > > + > > > + if (ndev->dev_id == ndev->dev_port) > > > + netdev_info_once(ndev, > > > + "\"%s\" wants to know my dev_id. Should it look at > > > dev_port instead? See Documentation/ABI/testing/sysfs-class-net for more > > > info.\n", > > > + current->comm); > > > + > > > + return sprintf(buf, "%#x\n", ndev->dev_id); > > > +} > > > +static DEVICE_ATTR_RO(dev_id); > > > + > > > +int ipoib_intercept_dev_id_attr(struct net_device *dev) > > > +{ > > > + device_remove_file(&dev->dev, &dev_attr_dev_id); > > > + return device_create_file(&dev->dev, &dev_attr_dev_id); > > > +} > > > > Isn't this racey with userspace? Ie what happens if udev is querying > > the dev_id right here? > > udev in particular does not use dev_id at all since 2014, because "why > would we keep using dev_id if it is not the right thing to use?". > > > > > Do we know there is no userspace doing this? > > > > Not for sure. > > If we move all the sysfs handling stuff we introduce in _add_port(): > - pkey > - umcast > - {create,delete}_child > - connected/datagram mode > to _ndo_init(), which is called by register_netdev before it sends > the netlink message, would that suffice to eliminate the race? > (Sysfs files for {create,delete}_child go to _parent_init() then). >
No, we can't, sorry for the noise. ndo_init() runs before the kobject
becomes available.
Anyway, our sysfs attributes being racy is unrelated to the patch series
subject, and I can't come up with any other ideas what to do with them
that do not involve adjustments to register_netdev.
> > > static struct net_device *ipoib_add_port(const char *format,
> > > struct ib_device *hca, u8 port)
> > > {
> > > @@ -2427,6 +2456,8 @@ static struct net_device *ipoib_add_port(const char
> > > *format,
> > > */
> > > ndev->priv_destructor = ipoib_intf_free;
> > >
> > > + if (ipoib_intercept_dev_id_attr(ndev))
> > > + goto sysfs_failed;
> >
> > No device_remove_file needed?
> >
>
> As far as I understand, unregister_netdevice takes care of it
> while destroying the related kobject.
>
> > Jason
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