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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 35F95C433E0 for ; Mon, 25 May 2020 08:55:02 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F4203206D5 for ; Mon, 25 May 2020 08:55:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="JfYCTJtI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F4203206D5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43306 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jd8sv-0006yY-6F for qemu-devel@archiver.kernel.org; Mon, 25 May 2020 04:55:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43022) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jd8sE-0006OE-CM; Mon, 25 May 2020 04:54:18 -0400 Received: from forwardcorp1o.mail.yandex.net ([95.108.205.193]:40664) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jd8sA-0007uY-Hl; Mon, 25 May 2020 04:54:16 -0400 Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id CD3B62E142F; Mon, 25 May 2020 11:54:09 +0300 (MSK) Received: from myt4-18a966dbd9be.qloud-c.yandex.net (myt4-18a966dbd9be.qloud-c.yandex.net [2a02:6b8:c00:12ad:0:640:18a9:66db]) by mxbackcorp1g.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id yoBAqrYgDS-s62aBUjq; Mon, 25 May 2020 11:54:09 +0300 Precedence: bulk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1590396849; bh=djfKV2KYi0Oy3hmBRbMvriEBCYdRbcoMpuxjmdftgjg=; h=In-Reply-To:Message-ID:Subject:To:From:References:Date:Cc; b=JfYCTJtIEnK0T6qtsgiaot+IlWxh951sADgU4fXChZqF3CeT15Fn/PXgB7AnyH6bf /oXic+z5XmffHrMHBnH/7LlPL3PWATHK3tqbjdKDU2RcfHa2kenyxNfjcInv5j74dq ESwuBw/E+lDy1ZxF2QOZmI15GgqcR0gTOz5Rrt+U= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b081:105::1:6]) by myt4-18a966dbd9be.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id PywxxnupS0-s6Yej4ov; Mon, 25 May 2020 11:54:06 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Date: Mon, 25 May 2020 11:54:05 +0300 From: Dima Stepanov To: Raphael Norwitz Subject: Re: [PATCH v3 2/2] vhost-user-blk: delay vhost_user_blk_disconnect Message-ID: <20200525085354.GA7592@dimastep-nix> References: <0dfb37f8728aba26c8d6c117018332a5b7dc9b56.1589989075.git.dimastep@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Received-SPF: pass client-ip=95.108.205.193; envelope-from=dimastep@yandex-team.ru; helo=forwardcorp1o.mail.yandex.net X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/25 04:54:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, mst@redhat.com, jasowang@redhat.com, dgilbert@redhat.com, QEMU , Raphael Norwitz , fengli@smartx.com, yc-core@yandex-team.ru, pbonzini@redhat.com, marcandre.lureau@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, May 25, 2020 at 12:00:10AM -0400, Raphael Norwitz wrote: > I'm mostly happy with this. A couple comments. > > On Wed, May 20, 2020 at 11:54 AM Dima Stepanov wrote: > > > > A socket write during vhost-user communication may trigger a disconnect > > event, calling vhost_user_blk_disconnect() and clearing all the > > vhost_dev structures holding data that vhost-user functions expect to > > remain valid to roll back initialization correctly. Delay the cleanup to > > keep vhost_dev structure valid. > > There are two possible states to handle: > > 1. RUN_STATE_PRELAUNCH: skip bh oneshot call and perform disconnect in > > the caller routine. > > 2. RUN_STATE_RUNNING: delay by using bh > > > > BH changes are based on the similar changes for the vhost-user-net > > device: > > commit e7c83a885f865128ae3cf1946f8cb538b63cbfba > > "vhost-user: delay vhost_user_stop" > > > I'd also give credit to Li Feng here - he sent a similar patch: > > https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg02255.html Yes, thanks for pointing me to it. > > > Signed-off-by: Dima Stepanov > > --- > > hw/block/vhost-user-blk.c | 49 +++++++++++++++++++++++++++++++++++++++++------ > > 1 file changed, 43 insertions(+), 6 deletions(-) > > > > diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c > > index 9d8c0b3..447fc9c 100644 > > --- a/hw/block/vhost-user-blk.c > > +++ b/hw/block/vhost-user-blk.c > > @@ -337,11 +337,6 @@ static void vhost_user_blk_disconnect(DeviceState *dev) > > VirtIODevice *vdev = VIRTIO_DEVICE(dev); > > VHostUserBlk *s = VHOST_USER_BLK(vdev); > > > > - if (!s->connected) { > > - return; > > - } > > - s->connected = false; > > - > > if (s->dev.started) { > > vhost_user_blk_stop(vdev); > > } > > @@ -349,6 +344,19 @@ static void vhost_user_blk_disconnect(DeviceState *dev) > > vhost_dev_cleanup(&s->dev); > > } > > > > +static void vhost_user_blk_event(void *opaque, QEMUChrEvent event); > > + > > +static void vhost_user_blk_chr_closed_bh(void *opaque) > > +{ > > + DeviceState *dev = opaque; > > + VirtIODevice *vdev = VIRTIO_DEVICE(dev); > > + VHostUserBlk *s = VHOST_USER_BLK(vdev); > > + > > + vhost_user_blk_disconnect(dev); > > + qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event, > > + NULL, opaque, NULL, true); > > +} > > + > > static void vhost_user_blk_event(void *opaque, QEMUChrEvent event) > > { > > DeviceState *dev = opaque; > > @@ -363,7 +371,28 @@ static void vhost_user_blk_event(void *opaque, QEMUChrEvent event) > > } > > break; > > case CHR_EVENT_CLOSED: > > - vhost_user_blk_disconnect(dev); > > + /* > > + * A close event may happen during a read/write, but vhost > > + * code assumes the vhost_dev remains setup, so delay the > > + * stop & clear. There are two possible paths to hit this > > + * disconnect event: > > + * 1. When VM is in the RUN_STATE_PRELAUNCH state. The > > + * vhost_user_blk_device_realize() is a caller. > > + * 2. In tha main loop phase after VM start. > > + * > > + * For p2 the disconnect event will be delayed. We can't > > + * do the same for p1, because we are not running the loop > > + * at this moment. So just skip this step and perform > > + * disconnect in the caller function. > > + */ > > + if (s->connected && runstate_is_running()) { > > + AioContext *ctx = qemu_get_current_aio_context(); > > + > > + qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL, NULL, > > + NULL, NULL, false); > > + aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, opaque); > > + } > > + s->connected = false; > > break; > > case CHR_EVENT_BREAK: > > case CHR_EVENT_MUX_IN: > > @@ -428,6 +457,14 @@ reconnect: > > > > ret = vhost_dev_get_config(&s->dev, (uint8_t *)&s->blkcfg, > > sizeof(struct virtio_blk_config)); > > I find checking s->connected before ret a little confusing. I think we > should also enforce a reconnect if s->connected is false. AFIK if > s->connected is false, ret must also be less than 0, but to be safe > I’d prefer something like: > > if (ret < 0 || !s->connected) { > if (!s->connected) { > /* > * Perform disconnect before making reconnect. More detailed > * comment why it was delayed is in the vhost_user_blk_event() > * routine. > */ > vhost_user_blk_disconnect(dev); > } > if (ret < 0) { > error_report(“vhost-user-blk: get block config failed”); > } > goto reconnect; > } > True. Thanks to Li Feng's patch i understood that i've overcomplicated the logic. We don't need this disconnect call here at all. I'll send a smaller reworked patch in this e-mail thread, just to continue review and discussion. > > + if (!s->connected) { > > + /* > > + * Perform disconnect before making reconnect. More detailed > > + * comment why it was delayed is in the vhost_user_blk_event() > > + * routine. > > + */ > > + vhost_user_blk_disconnect(dev); > > + } > > if (ret < 0) { > > error_report("vhost-user-blk: get block config failed"); > > goto reconnect; > > -- > > 2.7.4 > > > >