From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:35816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726287AbeKSU3R (ORCPT ); Mon, 19 Nov 2018 15:29:17 -0500 Date: Mon, 19 Nov 2018 11:06:06 +0100 From: Greg Kroah-Hartman To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, "jianchao.wang" , Guenter Roeck , stable@vger.kernel.org Subject: Re: [PATCH V2 for-4.21 1/2] blk-mq: not embed .mq_kobj and ctx->kobj into queue instance Message-ID: <20181119100606.GB19910@kroah.com> References: <20181116112311.4117-1-ming.lei@redhat.com> <20181116112311.4117-2-ming.lei@redhat.com> <20181116140521.GB4595@kroah.com> <20181117022637.GB8872@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181117022637.GB8872@ming.t460p> Sender: stable-owner@vger.kernel.org List-ID: On Sat, Nov 17, 2018 at 10:26:38AM +0800, Ming Lei wrote: > On Fri, Nov 16, 2018 at 06:05:21AM -0800, Greg Kroah-Hartman wrote: > > On Fri, Nov 16, 2018 at 07:23:10PM +0800, Ming Lei wrote: > > > @@ -456,7 +456,7 @@ struct request_queue { > > > /* > > > * mq queue kobject > > > */ > > > - struct kobject mq_kobj; > > > + struct kobject *mq_kobj; > > > > What is this kobject even used for? It wasn't obvious at all from this > > patch, why is it needed if you are not using it to reference count the > > larger structure here? > > All attributes and kobjects under /sys/block/$DEV/mq are covered by this kobject > actually, and all are for exposing blk-mq specific information, but now there is > only blk-mq, and legacy io path is removed. I am sorry, but I really can not parse this sentance at all. What Documentation/ABI/ entries are covered by this kobject, that should help me out more. And what do you mean by "legacy io"? > That is why I mentioned we may remove this kobject last time and move all under > /sys/block/$DEV/queue, however you thought that may break some userspace. Who relies on these sysfs files today? > If we want to backport them to stable, this patch may be a bit easier to go. Why do you want to backport any of this to stable? thanks, greg k-h