From patchwork Tue Mar 27 13:30:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev" X-Patchwork-Id: 891560 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=openvz.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 409X3J5tM5z9s1P for ; Wed, 28 Mar 2018 00:31:24 +1100 (AEDT) Received: from localhost ([::1]:34365 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0oh8-00079t-Af for incoming@patchwork.ozlabs.org; Tue, 27 Mar 2018 09:31:22 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33297) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0ogQ-00075B-RO for qemu-devel@nongnu.org; Tue, 27 Mar 2018 09:30:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f0ogM-0006Bi-Q2 for qemu-devel@nongnu.org; Tue, 27 Mar 2018 09:30:38 -0400 Received: from relay.sw.ru ([185.231.240.75]:33098) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f0ogD-00065O-3O; Tue, 27 Mar 2018 09:30:25 -0400 Received: from msk-vpn.virtuozzo.com ([195.214.232.6] helo=iris.sw.ru) by relay.sw.ru with esmtp (Exim 4.90_1) (envelope-from ) id 1f0og7-0008Sz-PC; Tue, 27 Mar 2018 16:30:20 +0300 From: "Denis V. Lunev" To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Tue, 27 Mar 2018 16:30:18 +0300 Message-Id: <1522157418-8954-1-git-send-email-den@openvz.org> X-Mailer: git-send-email 2.7.4 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 185.231.240.75 Subject: [Qemu-devel] [PATCH for 2.12 1/1] block: allow recursive calling of bdrv_set_aio_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: Kevin Wolf , "Denis V. Lunev" , Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" We have received the following assert on QEMU 2.9: (gdb) bt 0 0x00007f6f67d281f7 in __GI_raise () 1 0x00007f6f67d298e8 in __GI_abort () 2 0x00007f6f67d21266 in __assert_fail_base () 3 0x00007f6f67d21312 in __GI___assert_fail () 4 0x000055a8faf76f9f in bdrv_detach_aio_context () 5 0x000055a8faf76f68 in bdrv_detach_aio_context () 6 0x000055a8faf770c6 in bdrv_set_aio_context () 7 0x000055a8fafb780d in blk_set_aio_context () 8 0x000055a8faf7af08 in block_job_attached_aio_context () 9 0x000055a8faf77043 in bdrv_attach_aio_context () 10 0x000055a8faf770d9 in bdrv_set_aio_context () 11 0x000055a8fafb780d in blk_set_aio_context () 12 0x000055a8fad580e7 in virtio_blk_data_plane_stop () 13 0x000055a8faf11da5 in virtio_bus_stop_ioeventfd () 14 0x000055a8fad85604 in virtio_vmstate_change () 15 0x000055a8fae1ba52 in vm_state_notify () 16 0x000055a8fad273e5 in do_vm_stop () 17 vm_stop () 18 0x000055a8face8f28 in main_loop_should_exit () 19 main_loop () 20 main () (gdb) It does not look, that the code is fundumentally different in 2.12. block_job_attached_aio_context() calls backup_attached_aio_context(), which in turn calls bdrv_detach_aio_context() again. This results in assert(!bs->walking_aio_notifiers). The code in mirror is basically the same. The patch replaces boolean condition with incremental counter, which should solve the problem. Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Max Reitz --- include/block/block_int.h | 2 +- block.c | 12 ++++++------ 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/include/block/block_int.h b/include/block/block_int.h index 29cafa4..a290711 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -613,7 +613,7 @@ struct BlockDriverState { * BDS may register themselves in this list to be notified of changes * regarding this BDS's context */ QLIST_HEAD(, BdrvAioNotifier) aio_notifiers; - bool walking_aio_notifiers; /* to make removal during iteration safe */ + int walking_aio_notifiers; /* to make removal during iteration safe */ char filename[PATH_MAX]; char backing_file[PATH_MAX]; /* if non zero, the image is a diff of diff --git a/block.c b/block.c index a8da4f2..82cc07b 100644 --- a/block.c +++ b/block.c @@ -4739,8 +4739,7 @@ void bdrv_detach_aio_context(BlockDriverState *bs) return; } - assert(!bs->walking_aio_notifiers); - bs->walking_aio_notifiers = true; + bs->walking_aio_notifiers++; QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { if (baf->deleted) { bdrv_do_remove_aio_context_notifier(baf); @@ -4751,7 +4750,8 @@ void bdrv_detach_aio_context(BlockDriverState *bs) /* Never mind iterating again to check for ->deleted. bdrv_close() will * remove remaining aio notifiers if we aren't called again. */ - bs->walking_aio_notifiers = false; + bs->walking_aio_notifiers--; + assert(bs->walking_aio_notifiers >= 0); if (bs->drv->bdrv_detach_aio_context) { bs->drv->bdrv_detach_aio_context(bs); @@ -4782,8 +4782,7 @@ void bdrv_attach_aio_context(BlockDriverState *bs, bs->drv->bdrv_attach_aio_context(bs, new_context); } - assert(!bs->walking_aio_notifiers); - bs->walking_aio_notifiers = true; + bs->walking_aio_notifiers++; QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { if (ban->deleted) { bdrv_do_remove_aio_context_notifier(ban); @@ -4791,7 +4790,8 @@ void bdrv_attach_aio_context(BlockDriverState *bs, ban->attached_aio_context(new_context, ban->opaque); } } - bs->walking_aio_notifiers = false; + bs->walking_aio_notifiers--; + assert(bs->walking_aio_notifiers >= 0); } void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)