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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 EDAF7C3A5A6 for ; Mon, 23 Sep 2019 05:17:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE70120882 for ; Mon, 23 Sep 2019 05:17:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569215853; bh=2E6MBungT07O9bcJQK1ngcK36VNB0VeqzccQWXWm8t4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=uHJQK15tcI+grdc58bL86GQmDkTjj7K9lEbTIz7nIBAiCL5tbX4wAHEOi6AqbO8I4 wBqc0Ds0JSctW0QL4KniMEc9Zysd7Vo7LH1ej0rP1Edw61+hAldCoH/OWJ/Q0sOjt7 lrfGBaVkmVJwFvFQnm92zguajBNcT1NLb2cXbij4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389200AbfIWFRd (ORCPT ); Mon, 23 Sep 2019 01:17:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:37274 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389091AbfIWFRd (ORCPT ); Mon, 23 Sep 2019 01:17:33 -0400 Received: from localhost (unknown [77.137.89.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D68C92087C; Mon, 23 Sep 2019 05:17:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569215851; bh=2E6MBungT07O9bcJQK1ngcK36VNB0VeqzccQWXWm8t4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jp7eejgxvhX8/5ixm2BzUKbdqq4hPVySOYGOV+8ZTkoeBbIAsyZLij4Dss0XrhW1Y qgPfJNkT3T3nlwElLV3LWsLBhU/Z2yjMVqHQNEwSXke8/tq60ywkkHOh9MajKIKh// +GFHsAyfB+xbxH2C2vWHOVkvHp6yNva+ubJVa58k= Date: Mon, 23 Sep 2019 08:01:25 +0300 From: Leon Romanovsky To: "Liuyixian (Eason)" Cc: linux-rdma@vger.kernel.org, jgg@ziepe.ca, dledford@redhat.com, linuxarm@huawei.com Subject: Re: [PATCH for-next] RDMA/hns: Bugfix for flush cqe in case softirq and multi-process Message-ID: <20190923050125.GK14368@unreal> References: <1567686671-4331-1-git-send-email-liweihang@hisilicon.com> <20190908080303.GC26697@unreal> <20190910075216.GX6601@unreal> <94ad1f56-afc6-ec78-4aa2-85d03c644031@huawei.com> <0d4ce391-6619-783d-55a8-fa2524af7b9c@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0d4ce391-6619-783d-55a8-fa2524af7b9c@huawei.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Fri, Sep 20, 2019 at 11:55:56AM +0800, Liuyixian (Eason) wrote: > > > On 2019/9/11 21:17, Liuyixian (Eason) wrote: > > > > > > On 2019/9/10 15:52, Leon Romanovsky wrote: > >> On Tue, Sep 10, 2019 at 02:40:20PM +0800, Liuyixian (Eason) wrote: > >>> > >>> > >>> On 2019/9/8 16:03, Leon Romanovsky wrote: > >>>> On Thu, Sep 05, 2019 at 08:31:11PM +0800, Weihang Li wrote: > >>>>> From: Yixian Liu > >>>>> > >>>>> Hip08 has the feature flush cqe, which help to flush wqe in workqueue > >>>>> (sq and rq) when error happened by transmitting producer index with > >>>>> mailbox to hardware. Flush cqe is emplemented in post send and recv > >>>>> verbs. However, under NVMe cases, these verbs will be called under > >>>>> softirq context, and it will lead to following calltrace with > >>>>> current driver as mailbox used by flush cqe can go to sleep. > >>>>> > >>>>> This patch solves this problem by using workqueue to do flush cqe, > >>>> > >>>> Unbelievable, almost every bug in this driver is solved by introducing > >>>> workqueue. You should fix "sleep in flush path" issue and not by adding > >>>> new workqueue. > >>>> > >>> Hi Leon, > >>> > >>> Thanks for the comment. > >>> Up to now, for hip08, only one place use workqueue in hns_roce_hw_v2.c > >>> where for irq prints. > >> > >> Thanks to our lack of desire to add more workqueues and previous patches > >> which removed extra workqueues from the driver. > >> > > Thanks, I see. > > > >>> > >>> The solution for flush cqe in this patch is as follow: > >>> While flush cqe should be implement, the driver should modify qp to error state > >>> through mailbox with the newest product index of sq and rq, the hardware then > >>> can flush all outstanding wqes in sq and rq. > >>> > >>> That's the whole mechanism of flush cqe, also is the flush path. We can't > >>> change neither mailbox sleep attribute or flush cqe occurred in post send/recv. > >>> To avoid the calltrace of flush cqe in post verbs under NVMe softirq, > >>> use workqueue for flush cqe seems reasonable. > >>> > >>> As far as I know, there is no other alternative solution for this situation. > >>> I will be very grateful if you reminder me more information. > >> > >> ib_drain_rq/ib_drain_sq/ib_drain_qp???? > >> > > Hi Leon, > > > > I think these interfaces are designed for application to check that all wqes > > have been processed by hardware, so called drain or flush. However, it is not > > the same as the flush in this patch. The solution in this patch is used > > to help the hardware generate flush cqes for outstanding wqes while qp error. > > > Hi Leon, > > What's your opinion about above? Do you have any further comments? My opinion didn't change, you need to read discussions about ib_drain_*() functions, how and why they were introduced. It is a way to go. Thanks > > Thanks. > > >>> > >>> Thanks > >>> > >>>> _______________________________________________ > >>>> Linuxarm mailing list > >>>> Linuxarm@huawei.com > >>>> http://hulk.huawei.com/mailman/listinfo/linuxarm > >>>> > >>>> > >>> > >> > >> . > >> > > > > _______________________________________________ > > Linuxarm mailing list > > Linuxarm@huawei.com > > http://hulk.huawei.com/mailman/listinfo/linuxarm > > > > . > > >