From patchwork Thu Oct 19 13:19:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fiona Ebner X-Patchwork-Id: 13429164 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 00A2AC41513 for ; Thu, 19 Oct 2023 13:22:20 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qtSyB-0005rM-Ge; Thu, 19 Oct 2023 09:21:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qtSwR-0004VY-BJ; Thu, 19 Oct 2023 09:20:05 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qtSwO-0004Gg-OL; Thu, 19 Oct 2023 09:19:59 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 6CAA3430DF; Thu, 19 Oct 2023 15:19:41 +0200 (CEST) From: Fiona Ebner To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, vsementsov@yandex-team.ru, jsnow@redhat.com, hreitz@redhat.com, kwolf@redhat.com, pbonzini@redhat.com, t.lamprecht@proxmox.com Subject: [PATCH 3/3] blockdev: mirror: avoid potential deadlock when using iothread Date: Thu, 19 Oct 2023 15:19:36 +0200 Message-Id: <20231019131936.414246-4-f.ebner@proxmox.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231019131936.414246-1-f.ebner@proxmox.com> References: <20231019131936.414246-1-f.ebner@proxmox.com> MIME-Version: 1.0 Received-SPF: pass client-ip=94.136.29.106; envelope-from=f.ebner@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The bdrv_getlength() function is a generated co-wrapper and uses AIO_WAIT_WHILE() to wait for the spawned coroutine. AIO_WAIT_WHILE() expects the lock to be acquired exactly once. This can happen when the source node is explicitly specified as the @replaces parameter or if there is a filter on top of the source node. Signed-off-by: Fiona Ebner --- blockdev.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/blockdev.c b/blockdev.c index a01c62596b..877e3a26d4 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2968,6 +2968,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs, if (replaces) { BlockDriverState *to_replace_bs; + AioContext *aio_context; AioContext *replace_aio_context; int64_t bs_size, replace_size; @@ -2982,10 +2983,19 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs, return; } + aio_context = bdrv_get_aio_context(bs); replace_aio_context = bdrv_get_aio_context(to_replace_bs); - aio_context_acquire(replace_aio_context); + /* + * bdrv_getlength() is a co-wrapper and uses AIO_WAIT_WHILE. Be sure not + * to acquire the same AioContext twice. + */ + if (replace_aio_context != aio_context) { + aio_context_acquire(replace_aio_context); + } replace_size = bdrv_getlength(to_replace_bs); - aio_context_release(replace_aio_context); + if (replace_aio_context != aio_context) { + aio_context_release(replace_aio_context); + } if (replace_size < 0) { error_setg_errno(errp, -replace_size,