From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABE45C43381 for ; Mon, 4 Mar 2019 07:38:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 79CF7206B8 for ; Mon, 4 Mar 2019 07:38:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551685128; bh=TiJMTXFuaHWrUlW1vJUoJQrBvqZ48J3PLcmDJMexoEQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=LZXbk5NZ6Erx2kTSb7tZxLU5SOcYlDiCLf+QGQX2Bl0cwbF+8ulg7f8q+7HkaXohm po9PTaKmNfsC6aX9UDMz1hPXOfmOcv40SQO19RAOHCVW1rCm+M9rLeNRmOB65uiMza WM69BHxhm5KO2/GzDPXwR0yQa8xr4owdrYJ5PH20= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726069AbfCDHir (ORCPT ); Mon, 4 Mar 2019 02:38:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:35638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725938AbfCDHiq (ORCPT ); Mon, 4 Mar 2019 02:38:46 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 10107206B8; Mon, 4 Mar 2019 07:38:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551685125; bh=TiJMTXFuaHWrUlW1vJUoJQrBvqZ48J3PLcmDJMexoEQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Jg7sTjbPfZYQJT35IddXy73ojYHr7NX9CxSJhgla0tRKfWkfdDI3D51azLOLkoOCX VKOaS+x6EGznU75wxvuZq5ByD+Q54yYOZUY36qqr1bfLB78OhX5TsyCYLKlCWKXit4 ynVSPtfrAN/EohVrW+Gv0q1ewFK4VLFTReH535LM= Date: Mon, 4 Mar 2019 08:38:42 +0100 From: Greg KH To: Kimberly Brown Cc: Michael Kelley , Long Li , Sasha Levin , Stephen Hemminger , Dexuan Cui , "K. Y. Srinivasan" , Haiyang Zhang , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] Drivers: hv: vmbus: Expose monitor data only when monitor pages are used Message-ID: <20190304073842.GD23573@kroah.com> References: <20190226053530.GA2897@ubu-Virtual-Machine> <20190301191824.GA4108@ubu-Virtual-Machine> <20190303080543.GA32186@kroah.com> <20190303211128.GA2071@ubu-Virtual-Machine> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190303211128.GA2071@ubu-Virtual-Machine> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 03, 2019 at 04:11:28PM -0500, Kimberly Brown wrote: > On Sun, Mar 03, 2019 at 09:05:43AM +0100, Greg KH wrote: > > On Fri, Mar 01, 2019 at 02:18:24PM -0500, Kimberly Brown wrote: > > > +/* > > > + * 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, > > > > Why did you remove this line? > > I removed the default attributes because vmbus_chan_attrs contains > non-default attributes. You suggested that I use one attribute_group and > an is_visible() callback for the device-level attributes (see > https://lore.kernel.org/lkml/20190226081848.GA15659@kroah.com/). I > assumed (possibly incorrectly) that I should do the same for these > channel-level attributes. That is fine to have a callback, but why did you have to remove the default attribute pointer? The two should have nothing to do with each other. > > > }; > > > > > > /* > > > @@ -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); > > > > Why are you adding these "by hand"? What was wrong with using the > > default attribute group pointer? You also are not removing the > > attributes :( > > Are you referring to default_attrs in kobj_type? It's not an > attribute_group pointer, it's a pointer to an attribute pointer array. > The problem with using default_attrs is that all of the attributes are > visible. It shouldn't, the is_visable() callback will be called on each attribute when the group is created by the core. Did that not work properly when you tested this? > I'm fairly certain that the monitor attributes are being removed. > sysfs_create_group() uses the attribute_group's is_visible() callback to > control the attribute visibility. And, when I look at the sysfs files, I > can see that the monitor sysyfs files are removed. I mean you are not removing the group when the device goes away, not that the individual files are not present. If you leave the pointer to default_attributes there, the core will properly remove the sysfs attributes when the device is removed from the system. Otherwise you just "get lucky" if the attributes are removed or not. > In v3, I proposed moving the monitor attributes to a special > attribute_group and adding that group manually when needed. Do you > prefer that approach for the channel-level monitor attributes? No need for a special group here, just use the is_visable() callback like you currently are, all should be fine. I think you are adding more code than you need to in order to get this to all work properly :) thanks, greg k-h