From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from esa5.hgst.iphmx.com ([216.71.153.144]:58806 "EHLO esa5.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbdEaPhd (ORCPT ); Wed, 31 May 2017 11:37:33 -0400 From: Bart Van Assche To: "hch@infradead.org" , "linux-block@vger.kernel.org" , "axboe@fb.com" , "ming.lei@redhat.com" Subject: Re: [PATCH v3 5/9] blk-mq: fix blk_mq_quiesce_queue Date: Wed, 31 May 2017 15:37:30 +0000 Message-ID: <1496245049.2608.7.camel@sandisk.com> References: <20170531123706.20885-1-ming.lei@redhat.com> <20170531123706.20885-6-ming.lei@redhat.com> In-Reply-To: <20170531123706.20885-6-ming.lei@redhat.com> Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Wed, 2017-05-31 at 20:37 +0800, Ming Lei wrote: >=20 > + /* wait until queue is unquiesced */ > + wait_event_cmd(q->quiesce_wq, !blk_queue_quiesced(q), > + may_sleep ? > + srcu_read_unlock(&hctx->queue_rq_srcu, *srcu_idx) : > + rcu_read_unlock(), > + may_sleep ? > + *srcu_idx =3D srcu_read_lock(&hctx->queue_rq_srcu) : > + rcu_read_lock()); > + > if (q->elevator) > goto insert; What I see is that in this patch a new waitqueue has been introduced (quiesce_wq) and also that an explanation of why you think this new waitque= ue is needed is missing completely. Why is it that you think that the synchronize_scru() and synchronize_rcu() calls in blk_mq_quiesce_queue() ar= e not sufficient? If this new waitqueue is not needed, please remove that waitqueue again. Bart.=