From patchwork Tue Sep 25 15:15:35 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 10614353 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 35A70913 for ; Tue, 25 Sep 2018 15:56:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 24E932A8C0 for ; Tue, 25 Sep 2018 15:56:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 17C492A8C7; Tue, 25 Sep 2018 15:56:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id B1E5B2A8C0 for ; Tue, 25 Sep 2018 15:56:19 +0000 (UTC) Received: from localhost ([::1]:53916 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g4phD-00048f-3W for patchwork-qemu-devel@patchwork.kernel.org; Tue, 25 Sep 2018 11:56:19 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45628) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g4p5W-0001pC-BM for qemu-devel@nongnu.org; Tue, 25 Sep 2018 11:17:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g4p5U-0006Ch-CT for qemu-devel@nongnu.org; Tue, 25 Sep 2018 11:17:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50300) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1g4p5N-00064i-AR; Tue, 25 Sep 2018 11:17:13 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 621F63082140; Tue, 25 Sep 2018 15:17:12 +0000 (UTC) Received: from localhost (unknown [10.40.205.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DE6875DD79; Tue, 25 Sep 2018 15:17:11 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Tue, 25 Sep 2018 17:15:35 +0200 Message-Id: <20180925151541.18932-37-mreitz@redhat.com> In-Reply-To: <20180925151541.18932-1-mreitz@redhat.com> References: <20180925151541.18932-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Tue, 25 Sep 2018 15:17:12 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 36/42] block: Remove aio_poll() in bdrv_drain_poll variants X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Kevin Wolf bdrv_drain_poll_top_level() was buggy because it didn't release the AioContext lock of the node to be drained before calling aio_poll(). This way, callbacks called by aio_poll() would possibly take the lock a second time and run into a deadlock with a nested AIO_WAIT_WHILE() call. However, it turns out that the aio_poll() call isn't actually needed any more. It was introduced in commit 91af091f923, which is effectively reverted by this patch. The cases it was supposed to fix are now covered by bdrv_drain_poll(), which waits for block jobs to reach a quiescent state. Signed-off-by: Kevin Wolf Reviewed-by: Fam Zheng Reviewed-by: Max Reitz --- block/io.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/block/io.c b/block/io.c index 914ba78f1a..8b81ff3913 100644 --- a/block/io.c +++ b/block/io.c @@ -268,10 +268,6 @@ bool bdrv_drain_poll(BlockDriverState *bs, bool recursive, static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive, BdrvChild *ignore_parent) { - /* Execute pending BHs first and check everything else only after the BHs - * have executed. */ - while (aio_poll(bs->aio_context, false)); - return bdrv_drain_poll(bs, recursive, ignore_parent, false); } @@ -511,10 +507,6 @@ static bool bdrv_drain_all_poll(void) BlockDriverState *bs = NULL; bool result = false; - /* Execute pending BHs first (may modify the graph) and check everything - * else only after the BHs have executed. */ - while (aio_poll(qemu_get_aio_context(), false)); - /* bdrv_drain_poll() can't make changes to the graph and we are holding the * main AioContext lock, so iterating bdrv_next_all_states() is safe. */ while ((bs = bdrv_next_all_states(bs))) {