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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 882AFC4363A for ; Tue, 27 Oct 2020 19:36:13 +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 D7B9821D42 for ; Tue, 27 Oct 2020 19:36:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gz4N+qhi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7B9821D42 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]:39118 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kXUlP-0001Ij-Ek for qemu-devel@archiver.kernel.org; Tue, 27 Oct 2020 15:36:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49764) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kXUjx-0000Qa-WD for qemu-devel@nongnu.org; Tue, 27 Oct 2020 15:34:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:38917) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kXUjt-0005c8-Ko for qemu-devel@nongnu.org; Tue, 27 Oct 2020 15:34:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603827273; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DuWSL/hsCWyWedJExKwbsSl3EG4pyOquzL5/1F7MyUM=; b=gz4N+qhiCpFpkQ+1vn38wH0Ry0itZdHi2Wl0+DfqobgGIpw8dKLy7sFFze2shvSfryZorq wOt5iARopKP4slJ/MHr+8cK7470aAHdU9iSUp+sWhT7BJYyNAmfGKMR1sxQYKhH1tG4MZB d98ZGRJKClMy13dJB81WQePTz/jqWeU= 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-276-KgKPX77zPWeRJh23XH85jw-1; Tue, 27 Oct 2020 15:34:29 -0400 X-MC-Unique: KgKPX77zPWeRJh23XH85jw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1038F107ACF5 for ; Tue, 27 Oct 2020 19:34:29 +0000 (UTC) Received: from [10.3.112.145] (ovpn-112-145.phx2.redhat.com [10.3.112.145]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 54AEC60C15; Tue, 27 Oct 2020 19:34:22 +0000 (UTC) Subject: Re: [PULL 31/38] device-core: use RCU for list of children of a bus To: Paolo Bonzini , qemu-devel@nongnu.org References: <20201012203343.1105018-1-pbonzini@redhat.com> <20201012203343.1105018-32-pbonzini@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 27 Oct 2020 14:34:21 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <20201012203343.1105018-32-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/27 01:06:07 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 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, NICE_REPLY_A=-2.167, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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 , Maxim Levitsky Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/12/20 3:33 PM, Paolo Bonzini wrote: > From: Maxim Levitsky > > This fixes the race between device emulation code that tries to find > a child device to dispatch the request to (e.g a scsi disk), > and hotplug of a new device to that bus. > > Note that this doesn't convert all the readers of the list > but only these that might go over that list without BQL held. > > This is a very small first step to make this code thread safe. > > Suggested-by: Paolo Bonzini > Signed-off-by: Maxim Levitsky > Reviewed-by: Stefan Hajnoczi > Message-Id: <20200913160259.32145-5-mlevitsk@redhat.com> > [Use RCU_READ_LOCK_GUARD in more places, adjust testcase now that > the delay in DEVICE_DELETED due to RCU is more consistent. - Paolo] > Signed-off-by: Paolo Bonzini > Message-Id: <20201006123904.610658-9-mlevitsk@redhat.com> > Signed-off-by: Paolo Bonzini Git bisect lands on this commit as the reason that iotest 240 is failing: --- /home/eblake/qemu-tmp2/tests/qemu-iotests/240.out 2020-10-23 10:47:02.268392745 -0500 +++ /home/eblake/qemu-tmp2/build/tests/qemu-iotests/240.out.bad 2020-10-27 14:27:38.417188285 -0500 @@ -10,10 +10,10 @@ {"return": {}} {"return": {}} {"return": {}} +{"error": {"class": "GenericError", "desc": "Duplicate ID 'scsi-hd0' for device"}} +{"error": {"class": "DeviceNotFound", "desc": "Device 'scsi-hd0' not found"}} {"return": {}} -{"return": {}} -{"return": {}} -{"return": {}} +{"error": {"class": "GenericError", "desc": "Node hd0 is in use"}} {"return": {}} === Attach two SCSI disks using the same block device and the same iothread === @@ -29,7 +29,7 @@ {"return": {}} {"return": {}} {"return": {}} -{"return": {}} +{"error": {"class": "GenericError", "desc": "Node hd0 is in use"}} {"return": {}} === Attach two SCSI disks using the same block device but different iothreads === @@ -45,8 +45,8 @@ {"return": {}} {"error": {"class": "GenericError", "desc": "Cannot change iothread of active block backend"}} {"return": {}} -{"return": {}} -{"return": {}} +{"error": {"class": "GenericError", "desc": "Cannot change iothread of active block backend"}} +{"error": {"class": "DeviceNotFound", "desc": "Device 'scsi-hd1' not found"}} {"return": {}} {"return": {}} {"return": {}} Failures: 240 Failed 1 of 1 iotests -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org