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 DBDEEC43441 for ; Thu, 29 Nov 2018 20:39:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A281221019 for ; Thu, 29 Nov 2018 20:39:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A281221019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com 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 S1726333AbeK3HqH (ORCPT ); Fri, 30 Nov 2018 02:46:07 -0500 Received: from mga03.intel.com ([134.134.136.65]:14825 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726190AbeK3HqH (ORCPT ); Fri, 30 Nov 2018 02:46:07 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Nov 2018 12:39:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,295,1539673200"; d="scan'208";a="113897554" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga001.jf.intel.com with ESMTP; 29 Nov 2018 12:39:26 -0800 Date: Thu, 29 Nov 2018 13:36:32 -0700 From: Keith Busch To: Christoph Hellwig Cc: 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: <20181129203632.GE9377@localhost.localdomain> References: <20181129191310.9795-1-hch@lst.de> <20181129191310.9795-8-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181129191310.9795-8-hch@lst.de> User-Agent: Mutt/1.9.1 (2017-09-22) 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 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. You also need to clear NVMEQ_DELETE_ERROR somewhere later, maybe in nvme_init_queue(). From mboxrd@z Thu Jan 1 00:00:00 1970 From: keith.busch@intel.com (Keith Busch) Date: Thu, 29 Nov 2018 13:36:32 -0700 Subject: [PATCH 07/13] nvme-pci: don't poll from irq context when deleting queues In-Reply-To: <20181129191310.9795-8-hch@lst.de> References: <20181129191310.9795-1-hch@lst.de> <20181129191310.9795-8-hch@lst.de> Message-ID: <20181129203632.GE9377@localhost.localdomain> On Thu, Nov 29, 2018@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. You also need to clear NVMEQ_DELETE_ERROR somewhere later, maybe in nvme_init_queue().