From patchwork Mon Feb 1 12:50:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergio Lopez Pascual X-Patchwork-Id: 12058983 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3687C433DB for ; Mon, 1 Feb 2021 12:53:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 68D4364EA5 for ; Mon, 1 Feb 2021 12:53:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68D4364EA5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42884 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l6YiJ-0004St-BG for qemu-devel@archiver.kernel.org; Mon, 01 Feb 2021 07:53:55 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36168) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l6YfF-0001Uk-TH for qemu-devel@nongnu.org; Mon, 01 Feb 2021 07:50:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36116) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l6YfD-0004Kv-Dn for qemu-devel@nongnu.org; Mon, 01 Feb 2021 07:50:45 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612183842; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SJAGJCmimKYcS+clNb/u180mdWeuRwVVjwSl9bvxVJo=; b=KN0z9xTjERDKeuIteduWLrzG3bv9Mg4kKZejz3d9lFiKV4H2PNYd7X6wiKmkpgm5kiB78a A3vLXorunrMN1foY0KTiuBKmwvWcN2fWOFxWUBektIzMQ9/ez0jxp2FpmnWmSnhavn8x4+ 8vcdzsknFnWuSWKO/mcMIKVvApukYNs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-469-jlXvGvTGMbusheJGlG-PpQ-1; Mon, 01 Feb 2021 07:50:40 -0500 X-MC-Unique: jlXvGvTGMbusheJGlG-PpQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 776AE107ACE3; Mon, 1 Feb 2021 12:50:39 +0000 (UTC) Received: from toolbox.redhat.com (ovpn-113-25.rdu2.redhat.com [10.10.113.25]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0EFB010016DB; Mon, 1 Feb 2021 12:50:37 +0000 (UTC) From: Sergio Lopez To: qemu-devel@nongnu.org Subject: [PATCH v4 1/2] block: Avoid processing BDS twice in bdrv_set_aio_context_ignore() Date: Mon, 1 Feb 2021 13:50:31 +0100 Message-Id: <20210201125032.44713-2-slp@redhat.com> In-Reply-To: <20210201125032.44713-1-slp@redhat.com> References: <20210201125032.44713-1-slp@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=slp@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=slp@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.351, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Sergio Lopez , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Some graphs may contain an indirect reference to the first BDS in the chain that can be reached while walking it bottom->up from one its children. Doubling-processing of a BDS is especially problematic for the aio_notifiers, as they might attempt to work on both the old and the new AIO contexts. To avoid this problem, add every child and parent to the ignore list before actually processing them. Suggested-by: Kevin Wolf Signed-off-by: Sergio Lopez --- block.c | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-) diff --git a/block.c b/block.c index 8b9d457546..3da99312db 100644 --- a/block.c +++ b/block.c @@ -6414,7 +6414,10 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs, AioContext *new_context, GSList **ignore) { AioContext *old_context = bdrv_get_aio_context(bs); - BdrvChild *child; + GSList *children_to_process = NULL; + GSList *parents_to_process = NULL; + GSList *entry; + BdrvChild *child, *parent; g_assert(qemu_get_current_aio_context() == qemu_get_aio_context()); @@ -6429,16 +6432,33 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs, continue; } *ignore = g_slist_prepend(*ignore, child); - bdrv_set_aio_context_ignore(child->bs, new_context, ignore); + children_to_process = g_slist_prepend(children_to_process, child); } - QLIST_FOREACH(child, &bs->parents, next_parent) { - if (g_slist_find(*ignore, child)) { + + QLIST_FOREACH(parent, &bs->parents, next_parent) { + if (g_slist_find(*ignore, parent)) { continue; } - assert(child->klass->set_aio_ctx); - *ignore = g_slist_prepend(*ignore, child); - child->klass->set_aio_ctx(child, new_context, ignore); + *ignore = g_slist_prepend(*ignore, parent); + parents_to_process = g_slist_prepend(parents_to_process, parent); + } + + for (entry = children_to_process; + entry != NULL; + entry = g_slist_next(entry)) { + child = entry->data; + bdrv_set_aio_context_ignore(child->bs, new_context, ignore); + } + g_slist_free(children_to_process); + + for (entry = parents_to_process; + entry != NULL; + entry = g_slist_next(entry)) { + parent = entry->data; + assert(parent->klass->set_aio_ctx); + parent->klass->set_aio_ctx(parent, new_context, ignore); } + g_slist_free(parents_to_process); bdrv_detach_aio_context(bs);