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GET /api/patches/806827/?format=api
{ "id": 806827, "url": "http://patchwork.ozlabs.org/api/patches/806827/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/1503965694-10794-22-git-send-email-mdroth@linux.vnet.ibm.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<1503965694-10794-22-git-send-email-mdroth@linux.vnet.ibm.com>", "list_archive_url": null, "date": "2017-08-29T00:13:56", "name": "[21/79] aio: add missing aio_notify() to aio_enable_external()", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "b6bc2d128d66905ffd47d46a8be9db808649f976", "submitter": { "id": 5549, "url": "http://patchwork.ozlabs.org/api/people/5549/?format=api", "name": "Michael Roth", "email": "mdroth@linux.vnet.ibm.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/1503965694-10794-22-git-send-email-mdroth@linux.vnet.ibm.com/mbox/", "series": [ { "id": 281, "url": "http://patchwork.ozlabs.org/api/series/281/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=281", "date": "2017-08-29T00:13:45", "name": "Patch Round-up for stable 2.9.1, freeze on 2017-09-04", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/281/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/806827/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/806827/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org", "Authentication-Results": "ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=<UNKNOWN>)", "Received": [ "from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xh8gR0mLyz9s65\n\tfor <incoming@patchwork.ozlabs.org>;\n\tTue, 29 Aug 2017 10:30:43 +1000 (AEST)", "from localhost ([::1]:41963 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>)\n\tid 1dmUQS-0005xK-Ue\n\tfor incoming@patchwork.ozlabs.org; Mon, 28 Aug 2017 20:30:41 -0400", "from eggs.gnu.org ([2001:4830:134:3::10]:47575)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from <mdroth@linux.vnet.ibm.com>) id 1dmUCE-0000wx-9Q\n\tfor qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:59 -0400", "from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from <mdroth@linux.vnet.ibm.com>) id 1dmUCB-0005C4-21\n\tfor qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:58 -0400", "from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52595\n\thelo=mx0a-001b2d01.pphosted.com)\n\tby eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from <mdroth@linux.vnet.ibm.com>)\n\tid 1dmUCA-0005Bu-Rt\n\tfor qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:54 -0400", "from pps.filterd (m0098421.ppops.net [127.0.0.1])\n\tby mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id\n\tv7T0E9gd081527\n\tfor <qemu-devel@nongnu.org>; Mon, 28 Aug 2017 20:15:54 -0400", "from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201])\n\tby mx0a-001b2d01.pphosted.com with ESMTP id 2cmurncr8y-1\n\t(version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT)\n\tfor <qemu-devel@nongnu.org>; Mon, 28 Aug 2017 20:15:54 -0400", "from localhost\n\tby e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use\n\tOnly! Violators will be prosecuted\n\tfor <qemu-devel@nongnu.org> from <mdroth@linux.vnet.ibm.com>;\n\tMon, 28 Aug 2017 20:15:53 -0400", "from b01cxnp22034.gho.pok.ibm.com (9.57.198.24)\n\tby e11.ny.us.ibm.com (146.89.104.198) with IBM ESMTP SMTP Gateway:\n\tAuthorized Use Only! Violators will be prosecuted; \n\tMon, 28 Aug 2017 20:15:51 -0400", "from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com\n\t[9.57.199.109])\n\tby b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP\n\tid v7T0FoFS22544428; Tue, 29 Aug 2017 00:15:50 GMT", "from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1])\n\tby IMSVA (Postfix) with ESMTP id C37A1112054;\n\tMon, 28 Aug 2017 20:15:36 -0400 (EDT)", "from localhost (unknown [9.80.85.217])\n\tby b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP id 9080A112051;\n\tMon, 28 Aug 2017 20:15:36 -0400 (EDT)" ], "From": "Michael Roth <mdroth@linux.vnet.ibm.com>", "To": "qemu-devel@nongnu.org", "Date": "Mon, 28 Aug 2017 19:13:56 -0500", "X-Mailer": "git-send-email 2.7.4", "In-Reply-To": "<1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com>", "References": "<1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com>", "X-TM-AS-GCONF": "00", "x-cbid": "17082900-2213-0000-0000-00000210D341", "X-IBM-SpamModules-Scores": "", "X-IBM-SpamModules-Versions": "BY=3.00007630; HX=3.00000241; KW=3.00000007;\n\tPH=3.00000004; SC=3.00000226; SDB=6.00909027; UDB=6.00455849;\n\tIPR=6.00689279; \n\tBA=6.00005557; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009;\n\tZB=6.00000000; \n\tZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016909;\n\tXFM=3.00000015; UTC=2017-08-29 00:15:52", "X-IBM-AV-DETECTION": "SAVI=unused REMOTE=unused XFE=unused", "x-cbparentid": "17082900-2214-0000-0000-0000575DECBF", "Message-Id": "<1503965694-10794-22-git-send-email-mdroth@linux.vnet.ibm.com>", "X-Proofpoint-Virus-Version": "vendor=fsecure engine=2.50.10432:, ,\n\tdefinitions=2017-08-28_13:, , signatures=0", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n\tspamscore=0 suspectscore=1\n\tmalwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam\n\tadjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000\n\tdefinitions=main-1708290001", "X-detected-operating-system": "by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy]", "X-Received-From": "148.163.158.5", "Subject": "[Qemu-devel] [PATCH 21/79] aio: add missing aio_notify() to\n\taio_enable_external()", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.21", "Precedence": "list", "List-Id": "<qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n\t<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<http://lists.nongnu.org/archive/html/qemu-devel/>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n\t<mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Cc": "qemu-stable@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "\"Qemu-devel\"\n\t<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>" }, "content": "From: Stefan Hajnoczi <stefanha@redhat.com>\n\nThe main loop uses aio_disable_external()/aio_enable_external() to\ntemporarily disable processing of external AioContext clients like\ndevice emulation.\n\nThis allows monitor commands to quiesce I/O and prevent the guest from\nsubmitting new requests while a monitor command is in progress.\n\nThe aio_enable_external() API is currently broken when an IOThread is in\naio_poll() waiting for fd activity when the main loop re-enables\nexternal clients. Incrementing ctx->external_disable_cnt does not wake\nthe IOThread from ppoll(2) so fd processing remains suspended and leads\nto unresponsive emulated devices.\n\nThis patch adds an aio_notify() call to aio_enable_external() so the\nIOThread is kicked out of ppoll(2) and will re-arm the file descriptors.\n\nThe bug can be reproduced as follows:\n\n $ qemu -M accel=kvm -m 1024 \\\n -object iothread,id=iothread0 \\\n -device virtio-scsi-pci,iothread=iothread0,id=virtio-scsi-pci0 \\\n -drive if=none,id=drive0,aio=native,cache=none,format=raw,file=test.img \\\n -device scsi-hd,id=scsi-hd0,drive=drive0 \\\n -qmp tcp::5555,server,nowait\n\n $ scripts/qmp/qmp-shell localhost:5555\n (qemu) blockdev-snapshot-sync device=drive0 snapshot-file=sn1.qcow2\n mode=absolute-paths format=qcow2\n\nAfter blockdev-snapshot-sync completes the SCSI disk will be\nunresponsive. This leads to request timeouts inside the guest.\n\nReported-by: Qianqian Zhu <qizhu@redhat.com>\nReviewed-by: Fam Zheng <famz@redhat.com>\nSigned-off-by: Stefan Hajnoczi <stefanha@redhat.com>\nMessage-id: 20170508180705.20609-1-stefanha@redhat.com\nSuggested-by: Fam Zheng <famz@redhat.com>\nSigned-off-by: Stefan Hajnoczi <stefanha@redhat.com>\n(cherry picked from commit 321d1dba8bef9676a77e9399484e3cd8bf2cf16a)\nSigned-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>\n---\n include/block/aio.h | 10 ++++++++--\n 1 file changed, 8 insertions(+), 2 deletions(-)", "diff": "diff --git a/include/block/aio.h b/include/block/aio.h\nindex 406e323..e9aeeae 100644\n--- a/include/block/aio.h\n+++ b/include/block/aio.h\n@@ -454,8 +454,14 @@ static inline void aio_disable_external(AioContext *ctx)\n */\n static inline void aio_enable_external(AioContext *ctx)\n {\n- assert(ctx->external_disable_cnt > 0);\n- atomic_dec(&ctx->external_disable_cnt);\n+ int old;\n+\n+ old = atomic_fetch_dec(&ctx->external_disable_cnt);\n+ assert(old > 0);\n+ if (old == 1) {\n+ /* Kick event loop so it re-arms file descriptors */\n+ aio_notify(ctx);\n+ }\n }\n \n /**\n", "prefixes": [ "21/79" ] }