From patchwork Thu Nov 11 12:08:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12614729 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B39A3C433F5 for ; Thu, 11 Nov 2021 12:14:06 +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 7656A6109F for ; Thu, 11 Nov 2021 12:14:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7656A6109F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:55442 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ml8xx-00014X-Kr for qemu-devel@archiver.kernel.org; Thu, 11 Nov 2021 07:14:05 -0500 Received: from eggs.gnu.org ([209.51.188.92]:40210) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ml8t1-000082-8H for qemu-devel@nongnu.org; Thu, 11 Nov 2021 07:08:59 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:53171) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ml8sz-00036v-6J for qemu-devel@nongnu.org; Thu, 11 Nov 2021 07:08:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636632534; 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=uyzUp2gROLRX2Mtjs6Y0dXbVxkZC5iqmMyE5EANOx5Y=; b=MjwPi/KAqg6pUBDTQX16TWIQUXFkzEcZ4812YArJbnjloOPL511Mm/L0YnO462BJpHd8k9 PZNc+bNxRI0jbC6fOx9+c4JunDyLP5TT8ZIXL4fwhfSCtqStN535yDQS4uImfA/YItTA2I 8kCPbJZR63K/j/qXK71PtrzMsAKxwTw= 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-462-a3knXNu1OlmSnw3J3timvA-1; Thu, 11 Nov 2021 07:08:50 -0500 X-MC-Unique: a3knXNu1OlmSnw3J3timvA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 731F4101796A; Thu, 11 Nov 2021 12:08:49 +0000 (UTC) Received: from localhost (unknown [10.39.193.142]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EE6EA5C1A3; Thu, 11 Nov 2021 12:08:48 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 05/10] block: Pass BdrvChild ** to replace_child_noperm Date: Thu, 11 Nov 2021 13:08:24 +0100 Message-Id: <20211111120829.81329-6-hreitz@redhat.com> In-Reply-To: <20211111120829.81329-1-hreitz@redhat.com> References: <20211111120829.81329-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, 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_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Hanna Reitz , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" bdrv_replace_child_noperm() modifies BdrvChild.bs, and can potentially set it to NULL. That is dangerous, because BDS parents generally assume that their children's .bs pointer is never NULL. We therefore want to let bdrv_replace_child_noperm() set the corresponding BdrvChild pointer to NULL, too. This patch lays the foundation for it by passing a BdrvChild ** pointer to bdrv_replace_child_noperm() so that it can later use it to NULL the BdrvChild pointer immediately after setting BdrvChild.bs to NULL. (We will still need to undertake some intermediate steps, though.) Signed-off-by: Hanna Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy --- block.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/block.c b/block.c index c7d5aa5254..d668156eca 100644 --- a/block.c +++ b/block.c @@ -87,7 +87,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, static bool bdrv_recurse_has_child(BlockDriverState *bs, BlockDriverState *child); -static void bdrv_replace_child_noperm(BdrvChild *child, +static void bdrv_replace_child_noperm(BdrvChild **child, BlockDriverState *new_bs); static void bdrv_remove_file_or_backing_child(BlockDriverState *bs, BdrvChild *child, @@ -2270,7 +2270,7 @@ static void bdrv_replace_child_abort(void *opaque) BlockDriverState *new_bs = s->child->bs; /* old_bs reference is transparently moved from @s to @s->child */ - bdrv_replace_child_noperm(s->child, s->old_bs); + bdrv_replace_child_noperm(&s->child, s->old_bs); bdrv_unref(new_bs); } @@ -2300,7 +2300,7 @@ static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs, if (new_bs) { bdrv_ref(new_bs); } - bdrv_replace_child_noperm(child, new_bs); + bdrv_replace_child_noperm(&child, new_bs); /* old_bs reference is transparently moved from @child to @s */ } @@ -2672,9 +2672,10 @@ uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) return permissions[qapi_perm]; } -static void bdrv_replace_child_noperm(BdrvChild *child, +static void bdrv_replace_child_noperm(BdrvChild **childp, BlockDriverState *new_bs) { + BdrvChild *child = *childp; BlockDriverState *old_bs = child->bs; int new_bs_quiesce_counter; int drain_saldo; @@ -2767,7 +2768,7 @@ static void bdrv_attach_child_common_abort(void *opaque) BdrvChild *child = *s->child; BlockDriverState *bs = child->bs; - bdrv_replace_child_noperm(child, NULL); + bdrv_replace_child_noperm(s->child, NULL); if (bdrv_get_aio_context(bs) != s->old_child_ctx) { bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort); @@ -2867,7 +2868,7 @@ static int bdrv_attach_child_common(BlockDriverState *child_bs, } bdrv_ref(child_bs); - bdrv_replace_child_noperm(new_child, child_bs); + bdrv_replace_child_noperm(&new_child, child_bs); *child = new_child; @@ -2922,12 +2923,12 @@ static int bdrv_attach_child_noperm(BlockDriverState *parent_bs, return 0; } -static void bdrv_detach_child(BdrvChild *child) +static void bdrv_detach_child(BdrvChild **childp) { - BlockDriverState *old_bs = child->bs; + BlockDriverState *old_bs = (*childp)->bs; - bdrv_replace_child_noperm(child, NULL); - bdrv_child_free(child); + bdrv_replace_child_noperm(childp, NULL); + bdrv_child_free(*childp); if (old_bs) { /* @@ -3033,7 +3034,7 @@ void bdrv_root_unref_child(BdrvChild *child) BlockDriverState *child_bs; child_bs = child->bs; - bdrv_detach_child(child); + bdrv_detach_child(&child); bdrv_unref(child_bs); }