From patchwork Tue Mar 28 16:12:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev" X-Patchwork-Id: 9650217 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0F88F601E9 for ; Tue, 28 Mar 2017 16:15:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0164F28419 for ; Tue, 28 Mar 2017 16:15:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EA71228420; Tue, 28 Mar 2017 16:15:29 +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=-6.9 required=2.0 tests=BAYES_00,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 4F3A028419 for ; Tue, 28 Mar 2017 16:15:28 +0000 (UTC) Received: from localhost ([::1]:54254 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cstmJ-0000dr-Rc for patchwork-qemu-devel@patchwork.kernel.org; Tue, 28 Mar 2017 12:15:27 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54168) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cstjs-0007gO-Jf for qemu-devel@nongnu.org; Tue, 28 Mar 2017 12:12:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cstjo-0000uA-C1 for qemu-devel@nongnu.org; Tue, 28 Mar 2017 12:12:56 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:15723 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cstjo-0000t9-0b for qemu-devel@nongnu.org; Tue, 28 Mar 2017 12:12:52 -0400 Received: from iris.sw.ru (msk-vpn.virtuozzo.com [195.214.232.6]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id v2SGCkcp030825; Tue, 28 Mar 2017 19:12:47 +0300 (MSK) From: "Denis V. Lunev" To: qemu-devel@nongnu.org Date: Tue, 28 Mar 2017 19:12:46 +0300 Message-Id: <1490717566-25516-1-git-send-email-den@openvz.org> X-Mailer: git-send-email 2.7.4 X-detected-operating-system: by eggs.gnu.org: OpenBSD 3.x [fuzzy] X-Received-From: 195.214.232.25 Subject: [Qemu-devel] [PATCH for 2.9 1/1] block: add missed aio_context_acquire into release_drive 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: Kevin Wolf , "Denis V. Lunev" , Markus Armbruster , Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Recently we expirience hang with iothreads enabled with the following call trace: Thread 1 (Thread 0x7fa95efebc80 (LWP 177117)): 0 ppoll () from /lib64/libc.so.6 2 qemu_poll_ns () at qemu-timer.c:313 3 aio_poll () at aio-posix.c:457 4 bdrv_flush () at block/io.c:2641 5 bdrv_close () at block.c:2143 6 bdrv_delete () at block.c:2352 7 bdrv_unref () at block.c:3429 8 blk_remove_bs () at block/block-backend.c:427 9 blk_delete () at block/block-backend.c:178 10 blk_unref () at block/block-backend.c:226 11 object_property_del_all () at qom/object.c:399 12 object_finalize () at qom/object.c:461 13 object_unref () at qom/object.c:898 14 object_property_del_child () at qom/object.c:422 15 qmp_marshal_device_del () at qmp-marshal.c:1145 16 handle_qmp_command () at /usr/src/debug/qemu-2.6.0/monitor.c:3929 Technically bdrv_flush() stucks in while (rwco.ret == NOT_DONE) { aio_poll(aio_context, true); } but rwco.ret is equal to 0 thus we have missed wakeup. Code investigation reveals that we do not have performed aio_context_acquire() on this call stack. This patch adds missed lock. Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Max Reitz CC: Eric Blake CC: Markus Armbruster Reviewed-by: Fam Zheng --- hw/core/qdev-properties-system.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c index c34be1c..e885e65 100644 --- a/hw/core/qdev-properties-system.c +++ b/hw/core/qdev-properties-system.c @@ -124,8 +124,12 @@ static void release_drive(Object *obj, const char *name, void *opaque) BlockBackend **ptr = qdev_get_prop_ptr(dev, prop); if (*ptr) { + AioContext *ctx = blk_get_aio_context(*ptr); + + aio_context_acquire(ctx); blockdev_auto_del(*ptr); blk_detach_dev(*ptr, dev); + aio_context_release(ctx); } }