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?
Do we know there is no userspace doing this?
> 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?
Jason
