From nobody Tue Apr 23 12:22:58 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=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1568196305; cv=none; d=zoho.com; s=zohoarc; b=KugWV5cK/8HGmOTwU8JG+Z9e/aji6i6ww7KAOaABE5/a/82unWjw7CY3vxXpVM0A/SacRO1WKRlGuQXh0F4d3VV7pkDg/JSJg0qL6pQWLxiL0d5mU5UwrA13jvujfZPy7Be2YyhrZvCR0gKcLL3pBNOJRri3Dh4qDl4P0PllNMc= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1568196305; h=Content-Transfer-Encoding:Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:To:ARC-Authentication-Results; bh=2//0lXj8OJcmpj29BkWnutI4OKgi0n8zPtuyBcEVeN0=; b=Qa4n3WzYc61BsS/q3FxHYuUSNv6o2J981JrZGn5BppX0GppXmSk8AlGecpLvpVJpm58LMVPzB7S2IO50prlYx8a7+lArwcS6fPYRUitWMmsOxh7SKPBSwFvCbsgdfTT6bo+Ouhl3ubWI6jcRb3Gb5TLGhW/DBgrj5CdO+Gnt4yY= ARC-Authentication-Results: i=1; mx.zoho.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 header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1568196305816805.126918646647; Wed, 11 Sep 2019 03:05:05 -0700 (PDT) Received: from localhost ([::1]:49176 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7zUm-0000T5-P5 for importer@patchew.org; Wed, 11 Sep 2019 06:05:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48659) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7zTG-0007Nn-6y for qemu-devel@nongnu.org; Wed, 11 Sep 2019 06:03:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i7zTF-0004nP-2D for qemu-devel@nongnu.org; Wed, 11 Sep 2019 06:03:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52532) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i7zTA-0004m6-Cb; Wed, 11 Sep 2019 06:03:26 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 740C5315C02D; Wed, 11 Sep 2019 10:03:22 +0000 (UTC) Received: from localhost (ovpn-116-94.ams2.redhat.com [10.36.116.94]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 175656012A; Wed, 11 Sep 2019 10:03:17 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Wed, 11 Sep 2019 12:03:16 +0200 Message-Id: <20190911100316.32282-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Wed, 11 Sep 2019 10:03:22 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v3] blockjob: update nodes head while removing all bdrv 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 , qemu-stable@nongnu.org, qemu-devel@nongnu.org, Sergio Lopez , Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Sergio Lopez block_job_remove_all_bdrv() iterates through job->nodes, calling bdrv_root_unref_child() for each entry. The call to the latter may reach child_job_[can_]set_aio_ctx(), which will also attempt to traverse job->nodes, potentially finding entries that where freed on previous iterations. To avoid this situation, update job->nodes head on each iteration to ensure that already freed entries are no longer linked to the list. RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=3D1746631 Signed-off-by: Sergio Lopez Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz Reviewed-by: Sergio Lopez --- v3: - Rewrote the loop to make the whole function a bit simpler (Also, remove the node from the job->nodes list before unref'ing it, just to be extra-safe) --- blockjob.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/blockjob.c b/blockjob.c index 2abed0f551..c6e20e2fcd 100644 --- a/blockjob.c +++ b/blockjob.c @@ -175,14 +175,23 @@ static const BdrvChildRole child_job =3D { =20 void block_job_remove_all_bdrv(BlockJob *job) { - GSList *l; - for (l =3D job->nodes; l; l =3D l->next) { + /* + * bdrv_root_unref_child() may reach child_job_[can_]set_aio_ctx(), + * which will also traverse job->nodes, so consume the list one by + * one to make sure that such a concurrent access does not attempt + * to process an already freed BdrvChild. + */ + while (job->nodes) { + GSList *l =3D job->nodes; BdrvChild *c =3D l->data; + + job->nodes =3D l->next; + bdrv_op_unblock_all(c->bs, job->blocker); bdrv_root_unref_child(c); + + g_slist_free_1(l); } - g_slist_free(job->nodes); - job->nodes =3D NULL; } =20 bool block_job_has_bdrv(BlockJob *job, BlockDriverState *bs) --=20 2.21.0