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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 7C8C6C65BAE for ; Fri, 30 Nov 2018 08:08:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E4DA2147D for ; Fri, 30 Nov 2018 08:08:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E4DA2147D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726551AbeK3TQk (ORCPT ); Fri, 30 Nov 2018 14:16:40 -0500 Received: from verein.lst.de ([213.95.11.211]:48718 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726877AbeK3TQj (ORCPT ); Fri, 30 Nov 2018 14:16:39 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id 1B12168BDF; Fri, 30 Nov 2018 09:08:10 +0100 (CET) Date: Fri, 30 Nov 2018 09:08:09 +0100 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , Jens Axboe , Sagi Grimberg , Max Gurtovoy , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org Subject: Re: [PATCH 07/13] nvme-pci: don't poll from irq context when deleting queues Message-ID: <20181130080809.GC18936@lst.de> References: <20181129191310.9795-1-hch@lst.de> <20181129191310.9795-8-hch@lst.de> <20181129203632.GE9377@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181129203632.GE9377@localhost.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Nov 29, 2018 at 01:36:32PM -0700, Keith Busch wrote: > On Thu, Nov 29, 2018 at 08:13:04PM +0100, Christoph Hellwig wrote: > > This is the last place outside of nvme_irq that handles CQEs from > > interrupt context, and thus is in the way of removing the cq_lock for > > normal queues, and avoiding lockdep warnings on the poll queues, for > > which we already take it without IRQ disabling. > > > > Signed-off-by: Christoph Hellwig > > --- > > drivers/nvme/host/pci.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > > index 9ceba9900ca3..fb8db7d8170a 100644 > > --- a/drivers/nvme/host/pci.c > > +++ b/drivers/nvme/host/pci.c > > @@ -203,6 +203,7 @@ struct nvme_queue { > > unsigned long flags; > > #define NVMEQ_ENABLED 0 > > #define NVMEQ_SQ_CMB 1 > > +#define NVMEQ_DELETE_ERROR 2 > > u32 *dbbuf_sq_db; > > u32 *dbbuf_cq_db; > > u32 *dbbuf_sq_ei; > > @@ -2216,7 +2217,7 @@ static void nvme_del_cq_end(struct request *req, blk_status_t error) > > struct nvme_queue *nvmeq = req->end_io_data; > > > > if (!error) > > - nvme_poll_irqdisable(nvmeq, -1); > > + set_bit(NVMEQ_DELETE_ERROR, &nvmeq->flags); > > > > nvme_del_queue_end(req, error); > > } > > @@ -2258,11 +2259,20 @@ static bool nvme_disable_io_queues(struct nvme_dev *dev, u8 opcode) > > nr_queues--; > > sent++; > > } > > - while (sent--) { > > + while (sent) { > > + struct nvme_queue *nvmeq = &dev->queues[nr_queues + sent]; > > + > > timeout = wait_for_completion_io_timeout(&dev->ioq_wait, > > timeout); > > if (timeout == 0) > > return false; > > + > > + /* handle any remaining CQEs */ > > + if (opcode == nvme_admin_delete_cq && > > + !test_bit(NVMEQ_DELETE_ERROR, &nvmeq->flags)) > > + nvme_poll_irqdisable(nvmeq, -1); > > We're dispatchig lots of queue deletions in parallel, and they may > complete in any order. I don't see how you can guarantee that the > wait_for_completion() will return for the nvmeq that you're polling. True. I thought about moving the completion to the queue so that we have one completion per queue, and I should have done that after all. Note sure how I got the idea that not doing it is fine. > You also need to clear NVMEQ_DELETE_ERROR somewhere later, maybe in > nvme_init_queue(). Indeed.