From patchwork Fri Jan 29 02:19:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 8157461 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 8AC219F9A0 for ; Fri, 29 Jan 2016 02:20:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E60E8201B9 for ; Fri, 29 Jan 2016 02:20:13 +0000 (UTC) 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.kernel.org (Postfix) with ESMTPS id 33C7D20165 for ; Fri, 29 Jan 2016 02:20:13 +0000 (UTC) Received: from localhost ([::1]:59434 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOyfU-0007Hm-6Q for patchwork-qemu-devel@patchwork.kernel.org; Thu, 28 Jan 2016 21:20:12 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35282) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOyfN-0007H5-Om for qemu-devel@nongnu.org; Thu, 28 Jan 2016 21:20:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aOyfM-0001g1-LF for qemu-devel@nongnu.org; Thu, 28 Jan 2016 21:20:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59381) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOyfG-0001dc-FF; Thu, 28 Jan 2016 21:19:58 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 052DCA789; Fri, 29 Jan 2016 02:19:57 +0000 (UTC) Received: from fam-t430.redhat.com (vpn1-6-59.pek2.redhat.com [10.72.6.59]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u0T2JoYH012629; Thu, 28 Jan 2016 21:19:51 -0500 From: Fam Zheng To: qemu-devel@nongnu.org Date: Fri, 29 Jan 2016 10:19:49 +0800 Message-Id: <1454033989-16996-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Kevin Wolf , qemu-block@nongnu.org, Jeff Cody , mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, jsnow@redhat.com Subject: [Qemu-devel] [PATCH v3] blockjob: Fix hang in block_job_finish_sync X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP With a mirror job running on a virtio-blk dataplane disk, sending "q" to HMP will cause a dead loop in block_job_finish_sync. This is because the aio_poll() only processes the AIO context of bs which has no more work to do, while the main loop BH that is scheduled for setting the job->completed flag is never processed. Fix this by adding a flag in BlockJob structure, to track which context to poll for the block job to make progress. Its value is set to true when block_job_coroutine_complete() is called, and is checked in block_job_finish_sync to determine which context to poll. Suggested-by: Stefan Hajnoczi Signed-off-by: Fam Zheng --- blockjob.c | 5 ++++- include/block/blockjob.h | 9 +++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/blockjob.c b/blockjob.c index 80adb9d..25e1581 100644 --- a/blockjob.c +++ b/blockjob.c @@ -304,7 +304,9 @@ static int block_job_finish_sync(BlockJob *job, return -EBUSY; } while (!job->completed) { - aio_poll(bdrv_get_aio_context(bs), true); + aio_poll(job->deferred_to_main_loop ? qemu_get_aio_context() : + bdrv_get_aio_context(bs), + true); } ret = (job->cancelled && job->ret == 0) ? -ECANCELED : job->ret; block_job_unref(job); @@ -497,6 +499,7 @@ void block_job_defer_to_main_loop(BlockJob *job, data->aio_context = bdrv_get_aio_context(job->bs); data->fn = fn; data->opaque = opaque; + job->deferred_to_main_loop = true; qemu_bh_schedule(data->bh); } diff --git a/include/block/blockjob.h b/include/block/blockjob.h index d84ccd8..550de26 100644 --- a/include/block/blockjob.h +++ b/include/block/blockjob.h @@ -130,6 +130,11 @@ struct BlockJob { */ bool ready; + /** + * Set to true when the job has deferred work to the main loop. + */ + bool deferred_to_main_loop; + /** Status that is published by the query-block-jobs QMP API */ BlockDeviceIoStatus iostatus; @@ -402,6 +407,10 @@ typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque); * AioContext acquired. Block jobs must call bdrv_unref(), bdrv_close(), and * anything that uses bdrv_drain_all() in the main loop. * + * The job->deferred_to_main_loop flag will be set. Caller must clear it once + * the deferred work is done and the block job coroutine continues, unless it's + * completing immediately. + * * The @job AioContext is held while @fn executes. */ void block_job_defer_to_main_loop(BlockJob *job,