From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:52200 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729736AbeKQMlq (ORCPT ); Sat, 17 Nov 2018 07:41:46 -0500 Date: Sat, 17 Nov 2018 10:26:38 +0800 From: Ming Lei To: Greg Kroah-Hartman 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: <20181117022637.GB8872@ming.t460p> References: <20181116112311.4117-1-ming.lei@redhat.com> <20181116112311.4117-2-ming.lei@redhat.com> <20181116140521.GB4595@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116140521.GB4595@kroah.com> Sender: stable-owner@vger.kernel.org List-ID: 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/$DEV/mq are covered by this kobject actually, and all are for exposing blk-mq specific information, but now there is only blk-mq, and legacy io path is removed. That is why I mentioned we may remove this kobject last time and move all under /sys/block/$DEV/queue, however you thought that may break some userspace. If we want to backport them to stable, this patch may be a bit easier to go. Thanks, Ming