From patchwork Thu Sep 20 16:19:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 10608165 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 7484A913 for ; Thu, 20 Sep 2018 16:32:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 63F4F2DFF0 for ; Thu, 20 Sep 2018 16:32:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 57ACF2E020; Thu, 20 Sep 2018 16:32:05 +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 03A6A2DFF0 for ; Thu, 20 Sep 2018 16:32:04 +0000 (UTC) Received: from localhost ([::1]:52016 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g31s4-00071p-5E for patchwork-qemu-devel@patchwork.kernel.org; Thu, 20 Sep 2018 12:32:04 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45967) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g31hC-000537-1e for qemu-devel@nongnu.org; Thu, 20 Sep 2018 12:20:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g31hA-000668-Qi for qemu-devel@nongnu.org; Thu, 20 Sep 2018 12:20:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32854) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1g31h6-0005vT-Cf; Thu, 20 Sep 2018 12:20:44 -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 C1C8633BF0; Thu, 20 Sep 2018 16:20:43 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-116-231.ams2.redhat.com [10.36.116.231]) by smtp.corp.redhat.com (Postfix) with ESMTP id F27D985A33; Thu, 20 Sep 2018 16:20:41 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Thu, 20 Sep 2018 18:19:54 +0200 Message-Id: <20180920161958.27453-16-kwolf@redhat.com> In-Reply-To: <20180920161958.27453-1-kwolf@redhat.com> References: <20180920161958.27453-1-kwolf@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 [10.5.110.38]); Thu, 20 Sep 2018 16:20:43 +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] [PATCH v3 15/19] job: Avoid deadlocks in job_completed_txn_abort() 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: kwolf@redhat.com, famz@redhat.com, slp@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, pbonzini@redhat.com, jsnow@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Amongst others, job_finalize_single() calls the .prepare/.commit/.abort callbacks of the individual job driver. Recently, their use was adapted for all block jobs so that they involve code calling AIO_WAIT_WHILE() now. Such code must be called under the AioContext lock for the respective job, but without holding any other AioContext lock. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz --- job.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/job.c b/job.c index 00a1cd128d..0b021867da 100644 --- a/job.c +++ b/job.c @@ -718,6 +718,7 @@ static void job_cancel_async(Job *job, bool force) static void job_completed_txn_abort(Job *job) { + AioContext *outer_ctx = job->aio_context; AioContext *ctx; JobTxn *txn = job->txn; Job *other_job; @@ -731,23 +732,26 @@ static void job_completed_txn_abort(Job *job) txn->aborting = true; job_txn_ref(txn); - /* We are the first failed job. Cancel other jobs. */ - QLIST_FOREACH(other_job, &txn->jobs, txn_list) { - ctx = other_job->aio_context; - aio_context_acquire(ctx); - } + /* We can only hold the single job's AioContext lock while calling + * job_finalize_single() because the finalization callbacks can involve + * calls of AIO_WAIT_WHILE(), which could deadlock otherwise. */ + aio_context_release(outer_ctx); /* Other jobs are effectively cancelled by us, set the status for * them; this job, however, may or may not be cancelled, depending * on the caller, so leave it. */ QLIST_FOREACH(other_job, &txn->jobs, txn_list) { if (other_job != job) { + ctx = other_job->aio_context; + aio_context_acquire(ctx); job_cancel_async(other_job, false); + aio_context_release(ctx); } } while (!QLIST_EMPTY(&txn->jobs)) { other_job = QLIST_FIRST(&txn->jobs); ctx = other_job->aio_context; + aio_context_acquire(ctx); if (!job_is_completed(other_job)) { assert(job_is_cancelled(other_job)); job_finish_sync(other_job, NULL, NULL); @@ -756,6 +760,8 @@ static void job_completed_txn_abort(Job *job) aio_context_release(ctx); } + aio_context_acquire(outer_ctx); + job_txn_unref(txn); }