From: Kimberly Brown <kimbrow...@gmail.com> Sent: Friday, March 1, 2019 11:18
AM
>
> +/*
> + * Channel-level attribute_group callback function. Returns the permission
> for
> + * each attribute, and returns 0 if an attribute is not visible.
> + */
> +static umode_t vmbus_chan_attr_is_visible(struct kobject *kobj,
> + struct attribute *attr, int idx)
> +{
> + const struct vmbus_channel *channel =
> + container_of(kobj, struct vmbus_channel, kobj);
> +
> + /* Hide the monitor attributes if the monitor mechanism is not used. */
> + if (!channel->offermsg.monitor_allocated &&
> + (attr == &chan_attr_pending.attr ||
> + attr == &chan_attr_latency.attr ||
> + attr == &chan_attr_monitor_id.attr))
> + return 0;
> +
> + return attr->mode;
> +}
> +
> +static struct attribute_group vmbus_chan_group = {
> + .attrs = vmbus_chan_attrs,
> + .is_visible = vmbus_chan_attr_is_visible
> +};
> +
> static struct kobj_type vmbus_chan_ktype = {
> .sysfs_ops = &vmbus_chan_sysfs_ops,
> .release = vmbus_chan_release,
> - .default_attrs = vmbus_chan_attrs,
Just to double-check my understanding, removing the default_attrs
here means that in vmbus_add_channel_kobj(), the call to
kobject_init_and_add() will only create the sub-directory that is the
channel number. The sub-directory will be empty. Then the new
call to sysfs_create_group() that you added below will populate
the subdirectory, as filtered by vmbus_chan_attr_is_visible().
> };
>
> /*
> @@ -1571,6 +1624,12 @@ int vmbus_add_channel_kobj(struct hv_device *dev,
> struct
> vmbus_channel *channel)
> if (ret)
> return ret;
>
> + ret = sysfs_create_group(kobj, &vmbus_chan_group);
> + if (ret) {
> + pr_err("Unable to set up channel sysfs files\n");
> + return ret;
In this error case, the previously created sub-directory that is the
channel number needs to be deleted/cleaned up.
> + }
> +
Michael
