From nobody Sun May 5 06:02:15 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=virtuozzo.com Return-Path: Received: from lists.gnu.org (209.51.188.17 [209.51.188.17]) by mx.zohomail.com with SMTPS id 1550222486403914.1120576436749; Fri, 15 Feb 2019 01:21:26 -0800 (PST) Received: from localhost ([127.0.0.1]:35158 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1guZgL-0003cQ-GA for importer@patchew.org; Fri, 15 Feb 2019 04:21:17 -0500 Received: from eggs.gnu.org ([209.51.188.92]:45295) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1guZfJ-0003GC-4c for qemu-devel@nongnu.org; Fri, 15 Feb 2019 04:20:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1guZfI-0007qx-CR for qemu-devel@nongnu.org; Fri, 15 Feb 2019 04:20:13 -0500 Received: from relay.sw.ru ([185.231.240.75]:44440) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1guZf6-0007aj-Vb; Fri, 15 Feb 2019 04:20:02 -0500 Received: from [10.94.4.71] (helo=dptest2.qa.sw.ru) by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1guZf2-0003RS-6z; Fri, 15 Feb 2019 12:19:56 +0300 From: Denis Plotnikov To: kwolf@redhat.com, mreitz@redhat.com Date: Fri, 15 Feb 2019 12:19:50 +0300 Message-Id: <20190215091950.20270-1-dplotnikov@virtuozzo.com> X-Mailer: git-send-email 2.17.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 185.231.240.75 Subject: [Qemu-devel] [PATCH] block: don't set the same context 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: qemu-devel@nongnu.org, qemu-block@nongnu.org, den@virtuozzo.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Adds a fast path on aio context setting preventing unnecessary context setting routine. Also, it prevents issues with cyclic walk of child bds-es appeared because of registring aio walking notifiers: Call stack: 0 __GI_raise 1 __GI_abort 2 __assert_fail_base 3 __GI___assert_fail 4 bdrv_detach_aio_context (bs=3D0x55f54d65c000) <<< 5 bdrv_detach_aio_context (bs=3D0x55f54fc8a800) 6 bdrv_set_aio_context (bs=3D0x55f54fc8a800, ...) 7 block_job_attached_aio_context 8 bdrv_attach_aio_context (bs=3D0x55f54d65c000, ...) <<< 9 bdrv_set_aio_context (bs=3D0x55f54d65c000) 10 blk_set_aio_context 11 virtio_blk_data_plane_stop 12 virtio_bus_stop_ioeventfd 13 virtio_vmstate_change 14 vm_state_notify (running=3D0, state=3DRUN_STATE_SHUTDOWN) 15 do_vm_stop (state=3DRUN_STATE_SHUTDOWN, send_stop=3Dtrue) 16 vm_stop (state=3DRUN_STATE_SHUTDOWN) 17 main_loop_should_exit 18 main_loop 19 main This can happen because of "new" context attachment to VM disk bds. When attaching a new context the corresponding aio context handler is called for each of aio_notifiers registered on the VM disk bds context. Among those handlers, there is the block_job_attached_aio_context handler which sets a new aio context for the block job bds. When doing so, the old context is detached from all the block job bds children and one of them is the VM disk bds, serving as backing store for the blockjob bds, although the VM disk bds is actually the initializer of that process. Since the VM disk bds is protected with walking_aio_notifiers flag from double processing in recursive calls, the assert fires. Signed-off-by: Denis Plotnikov --- block.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block.c b/block.c index adda221c2c..5742545e7a 100644 --- a/block.c +++ b/block.c @@ -5263,6 +5263,10 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioC= ontext *new_context) { AioContext *ctx =3D bdrv_get_aio_context(bs); =20 + if (ctx =3D=3D new_context) { + return; + } + aio_disable_external(ctx); bdrv_parent_drained_begin(bs, NULL, false); bdrv_drain(bs); /* ensure there are no in-flight requests */ --=20 2.17.0