linux-kernel - Re: [PATCH v5] Drivers: hv: vmbus: Expose monitor data only when monitor pages are used

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Date:   Sat, 9 Mar 2019 08:21:35 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Kimberly Brown <kimbrownkd@...il.com>
Cc:     Michael Kelley <mikelley@...rosoft.com>,
        Long Li <longli@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] Drivers: hv: vmbus: Expose monitor data only when
 monitor pages are used

On Fri, Mar 08, 2019 at 05:46:11PM -0500, Kimberly Brown wrote:
>  static struct kobj_type vmbus_chan_ktype = {
>  	.sysfs_ops = &vmbus_chan_sysfs_ops,
>  	.release = vmbus_chan_release,
> -	.default_attrs = vmbus_chan_attrs,

As discussed on IRC, a kobj_type needs to get an attribute group one of
these days, not just a attribute list :)

So thanks for persisting with this, sorry for the earlier review
comments, you were totally right about this, nice work.

Minor review comments below:

>  };
>  
>  /*
> @@ -1571,11 +1624,34 @@ 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);
> +	channel->sysfs_group_ready = !ret;

Why do you need this flag?

> +
> +	if (ret) {
> +		/*
> +		 * If an error is returned to the calling functions, those
> +		 * functions will call kobject_put() on the channel kobject,
> +		 * which will cleanup the empty channel directory created by
> +		 * kobject_init_and_add().

Why is this comment needed?

> +		 */
> +		pr_err("Unable to set up channel sysfs files\n");

dev_err() to show who had the problem with the files?

> +		return ret;
> +	}
> +
>  	kobject_uevent(kobj, KOBJ_ADD);
>  
>  	return 0;
>  }
>  
> +/*
> + * vmbus_remove_channel_attr_group - remove the channel's attribute group
> + */
> +void vmbus_remove_channel_attr_group(struct vmbus_channel *channel)
> +{
> +	if (channel->sysfs_group_ready)
> +		sysfs_remove_group(&channel->kobj, &vmbus_chan_group);

You should be able to just always remove these, no need for a flag to
say you have created them or not, right?

thanks,

greg k-h