From nobody Wed Nov 5 14:24:48 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 153506279930983.21704013152225; Thu, 23 Aug 2018 15:19:59 -0700 (PDT) Received: from localhost ([::1]:38973 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsxxO-0003Ap-5e for importer@patchew.org; Thu, 23 Aug 2018 18:19:58 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57087) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsxrr-0006q4-Bn for qemu-devel@nongnu.org; Thu, 23 Aug 2018 18:14:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fsxro-0004Fo-5l for qemu-devel@nongnu.org; Thu, 23 Aug 2018 18:14:15 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:53426 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fsxms-0001tX-CF; Thu, 23 Aug 2018 18:09:06 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9431A40216FC; Thu, 23 Aug 2018 22:09:05 +0000 (UTC) Received: from probe.bos.redhat.com (dhcp-17-97.bos.redhat.com [10.18.17.97]) by smtp.corp.redhat.com (Postfix) with ESMTP id 531321C70B; Thu, 23 Aug 2018 22:09:05 +0000 (UTC) From: John Snow To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Thu, 23 Aug 2018 18:08:50 -0400 Message-Id: <20180823220856.10094-4-jsnow@redhat.com> In-Reply-To: <20180823220856.10094-1-jsnow@redhat.com> References: <20180823220856.10094-1-jsnow@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Thu, 23 Aug 2018 22:09:05 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Thu, 23 Aug 2018 22:09:05 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jsnow@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v2 3/9] jobs: add exit shim 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, Jeff Cody , Max Reitz , jtc@redhat.com, Stefan Hajnoczi , John Snow Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RDMRC_1 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" All jobs do the same thing when they leave their running loop: - Store the return code in a structure - wait to receive this structure in the main thread - signal job completion via job_completed Few jobs do anything beyond exactly this. Consolidate this exit logic for a net reduction in SLOC. More seriously, when we utilize job_defer_to_main_loop_bh to call a function that calls job_completed, job_finalize_single will run in a context where it has recursively taken the aio_context lock, which can cause hangs if it puts down a reference that causes a flush. You can observe this in practice by looking at mirror_exit's careful placement of job_completed and bdrv_unref calls. If we centralize job exiting, we can signal job completion from outside of the aio_context, which should allow for job cleanup code to run with only one lock, which makes cleanup callbacks less tricky to write. Signed-off-by: John Snow Reviewed-by: Max Reitz --- include/qemu/job.h | 11 +++++++++++ job.c | 18 ++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/qemu/job.h b/include/qemu/job.h index 5c92c53ef0..c67f6a647e 100644 --- a/include/qemu/job.h +++ b/include/qemu/job.h @@ -204,6 +204,17 @@ struct JobDriver { */ void (*drain)(Job *job); =20 + /** + * If the callback is not NULL, exit will be invoked from the main thr= ead + * when the job's coroutine has finished, but before transactional + * convergence; before @prepare or @abort. + * + * FIXME TODO: This callback is only temporary to transition remaining= jobs + * to prepare/commit/abort/clean callbacks and will be removed before = 3.1. + * is released. + */ + void (*exit)(Job *job); + /** * If the callback is not NULL, prepare will be invoked when all the j= obs * belonging to the same transaction complete; or upon this job's comp= letion diff --git a/job.c b/job.c index bc1d970df4..bc8dad4e71 100644 --- a/job.c +++ b/job.c @@ -535,6 +535,18 @@ void job_drain(Job *job) } } =20 +static void job_exit(void *opaque) +{ + Job *job =3D (Job *)opaque; + AioContext *aio_context =3D job->aio_context; + + if (job->driver->exit) { + aio_context_acquire(aio_context); + job->driver->exit(job); + aio_context_release(aio_context); + } + job_completed(job, job->ret); +} =20 /** * All jobs must allow a pause point before entering their job proper. This @@ -547,6 +559,12 @@ static void coroutine_fn job_co_entry(void *opaque) assert(job && job->driver && job->driver->run); job_pause_point(job); job->ret =3D job->driver->run(job, &job->err); + if (!job->deferred_to_main_loop) { + job->deferred_to_main_loop =3D true; + aio_bh_schedule_oneshot(qemu_get_aio_context(), + job_exit, + job); + } } =20 =20 --=20 2.14.4