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=-6.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 96973C388F9 for ; Tue, 27 Oct 2020 11:39:08 +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 E30DF20735 for ; Tue, 27 Oct 2020 11:39:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LMjq//GO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E30DF20735 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35766 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kXNJi-0005mf-Rj for qemu-devel@archiver.kernel.org; Tue, 27 Oct 2020 07:39:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44938) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kXMyb-0000YY-E1 for qemu-devel@nongnu.org; Tue, 27 Oct 2020 07:17:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:34947) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kXMyU-0003BH-1u for qemu-devel@nongnu.org; Tue, 27 Oct 2020 07:17:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603797425; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5fxboEc+Fec5apjC6Kad/Sl6RFHELsHnsijVve8SF6M=; b=LMjq//GOd/5yrkL9ugv7mQZljx1b61u8ghVhsa68aWF8wJ1ZhSqGfKcRCPMnfQT69k1ifA mRuI0LEjdUPXYE8DrZPSoS1pk5J9Dbrd1eA++U2M9R0MnBrUrzao8FzX884raJ3kzznmWU +sWV8+kJxgtVnNV0c5jLxjVCcuFJG20= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-573-hIBxJr5ONf2B1FhlrnS24g-1; Tue, 27 Oct 2020 07:17:00 -0400 X-MC-Unique: hIBxJr5ONf2B1FhlrnS24g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A964D801FDD; Tue, 27 Oct 2020 11:16:59 +0000 (UTC) Received: from merkur.fritz.box (ovpn-114-16.ams2.redhat.com [10.36.114.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 61BF355790; Tue, 27 Oct 2020 11:16:55 +0000 (UTC) Date: Tue, 27 Oct 2020 12:16:53 +0100 From: Kevin Wolf To: Greg Kurz Subject: Re: [PATCH v2] block: End quiescent sections when a BDS is deleted Message-ID: <20201027111653.GC4628@merkur.fritz.box> References: <160346526998.272601.9045392804399803158.stgit@bahia.lan> MIME-Version: 1.0 In-Reply-To: <160346526998.272601.9045392804399803158.stgit@bahia.lan> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/27 01:06:06 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 23.10.2020 um 17:01 hat Greg Kurz geschrieben: > If a BDS gets deleted during blk_drain_all(), it might miss a > call to bdrv_do_drained_end(). This means missing a call to > aio_enable_external() and the AIO context remains disabled for > ever. This can cause a device to become irresponsive and to > disrupt the guest execution, ie. hang, loop forever or worse. > > This scenario is quite easy to encounter with virtio-scsi > on POWER when punching multiple blockdev-create QMP commands > while the guest is booting and it is still running the SLOF > firmware. This happens because SLOF disables/re-enables PCI > devices multiple times via IO/MEM/MASTER bits of PCI_COMMAND > register after the initial probe/feature negotiation, as it > tends to work with a single device at a time at various stages > like probing and running block/network bootloaders without > doing a full reset in-between. This naturally generates many > dataplane stops and starts, and thus many drain sections that > can race with blockdev_create_run(). In the end, SLOF bails > out. > > It is somehow reproducible on x86 but it requires to generate > articial dataplane start/stop activity with stop/cont QMP > commands. In this case, seabios ends up looping for ever, > waiting for the virtio-scsi device to send a response to > a command it never received. > > Add a helper that pairs all previously called bdrv_do_drained_begin() > with a bdrv_do_drained_end() and call it from bdrv_close(). > While at it, update the "/bdrv-drain/graph-change/drain_all" > test in test-bdrv-drain so that it can catch the issue. > > BugId: https://bugzilla.redhat.com/show_bug.cgi?id=1874441 > Signed-off-by: Greg Kurz Thanks, applied to the block branch. Kevin