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=-6.6 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 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 3E074C2BA17 for ; Mon, 6 Apr 2020 17:16:15 +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 09B9B249BC for ; Mon, 6 Apr 2020 17:16:15 +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="egkKj8O3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 09B9B249BC 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]:35454 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jLVM6-0001Wu-5h for qemu-devel@archiver.kernel.org; Mon, 06 Apr 2020 13:16:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57582) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jLVL6-0008Uv-OG for qemu-devel@nongnu.org; Mon, 06 Apr 2020 13:15:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jLVL5-00080f-KF for qemu-devel@nongnu.org; Mon, 06 Apr 2020 13:15:12 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:29489 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jLVL5-00080W-Gf for qemu-devel@nongnu.org; Mon, 06 Apr 2020 13:15:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586193311; 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=HF/tVOpn66mmfW9If+9ev51Qxkj3zPw+qslEcdMudv8=; b=egkKj8O3laj8aKMNRdLbjYOcaOHJzYqMQsRXDB7kK3Ni8W/HGHuoarRwoevEIvPXOdcGIO QtyaPS5AuYc7+uaSkGWRzR+iVbPdXiDkNqUtKCDIqSdSAnNB06n6q0qhbhmY32BI2DcWyC QlIWvbTJ5CkbSSj+lKYhBYQQjkwbk7w= 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-506-LD_WZfecP6qd_69ZXYcu1A-1; Mon, 06 Apr 2020 13:15:06 -0400 X-MC-Unique: LD_WZfecP6qd_69ZXYcu1A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E020C10FD887; Mon, 6 Apr 2020 17:14:15 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-113-74.ams2.redhat.com [10.36.113.74]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1472611CC04; Mon, 6 Apr 2020 17:14:13 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH for-5.0 v2 3/3] block: Fix blk->in_flight during blk_wait_while_drained() Date: Mon, 6 Apr 2020 19:14:03 +0200 Message-Id: <20200406171403.6761-4-kwolf@redhat.com> In-Reply-To: <20200406171403.6761-1-kwolf@redhat.com> References: <20200406171403.6761-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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: kwolf@redhat.com, vsementsov@virtuozzo.com, s.reiter@proxmox.com, qemu-devel@nongnu.org, dietmar@proxmox.com, stefanha@redhat.com, mreitz@redhat.com, t.lamprecht@proxmox.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Waiting in blk_wait_while_drained() while blk->in_flight is increased for the current request is wrong because it will cause the drain operation to deadlock. This patch makes sure that blk_wait_while_drained() is called with blk->in_flight increased exactly once for the current request, and that it temporarily decreases the counter while it waits. Fixes: cf3129323f900ef5ddbccbe86e4fa801e88c566e Signed-off-by: Kevin Wolf --- block/block-backend.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/block/block-backend.c b/block/block-backend.c index d330e08b05..f621435f0b 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1140,10 +1140,15 @@ static int blk_check_byte_request(BlockBackend *blk= , int64_t offset, return 0; } =20 +/* To be called between exactly one pair of blk_inc/dec_in_flight() */ static void coroutine_fn blk_wait_while_drained(BlockBackend *blk) { + assert(blk->in_flight > 0); + if (blk->quiesce_counter && !blk->disable_request_queuing) { + blk_dec_in_flight(blk); qemu_co_queue_wait(&blk->queued_requests, NULL); + blk_inc_in_flight(blk); } } =20 @@ -1416,12 +1421,6 @@ static void blk_aio_read_entry(void *opaque) BlkRwCo *rwco =3D &acb->rwco; QEMUIOVector *qiov =3D rwco->iobuf; =20 - if (rwco->blk->quiesce_counter) { - blk_dec_in_flight(rwco->blk); - blk_wait_while_drained(rwco->blk); - blk_inc_in_flight(rwco->blk); - } - assert(qiov->size =3D=3D acb->bytes); rwco->ret =3D blk_do_preadv(rwco->blk, rwco->offset, acb->bytes, qiov, rwco->flags); @@ -1434,12 +1433,6 @@ static void blk_aio_write_entry(void *opaque) BlkRwCo *rwco =3D &acb->rwco; QEMUIOVector *qiov =3D rwco->iobuf; =20 - if (rwco->blk->quiesce_counter) { - blk_dec_in_flight(rwco->blk); - blk_wait_while_drained(rwco->blk); - blk_inc_in_flight(rwco->blk); - } - assert(!qiov || qiov->size =3D=3D acb->bytes); rwco->ret =3D blk_do_pwritev_part(rwco->blk, rwco->offset, acb->bytes, qiov, 0, rwco->flags); --=20 2.20.1