From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 0BAF1C04EBF for ; Mon, 23 Sep 2019 12:09:44 +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 D280420820 for ; Mon, 23 Sep 2019 12:09:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D280420820 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]:55582 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCN9y-0004Ko-2I for qemu-devel@archiver.kernel.org; Mon, 23 Sep 2019 08:09:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45810) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCN1l-00067c-GL for qemu-devel@nongnu.org; Mon, 23 Sep 2019 08:01:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCN1j-0002MF-3P for qemu-devel@nongnu.org; Mon, 23 Sep 2019 08:01:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56796) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCN1i-0002Ln-KK for qemu-devel@nongnu.org; Mon, 23 Sep 2019 08:01:10 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id B8D1B88307; Mon, 23 Sep 2019 12:01:09 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-117-142.ams2.redhat.com [10.36.117.142]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 04F461001B00; Mon, 23 Sep 2019 12:01:07 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A4BB3113864E; Mon, 23 Sep 2019 14:01:05 +0200 (CEST) From: Markus Armbruster To: Eric Blake Subject: Re: [Qemu-devel] [PATCH 18/19] qapi: Fix excessive QAPISchemaEntity.check() recursion References: <20190914153506.2151-1-armbru@redhat.com> <20190914153506.2151-19-armbru@redhat.com> Date: Mon, 23 Sep 2019 14:01:05 +0200 In-Reply-To: (Eric Blake's message of "Tue, 17 Sep 2019 14:26:35 -0500") Message-ID: <87ef07nrwe.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 23 Sep 2019 12:01:09 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 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: marcandre.lureau@redhat.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eric Blake writes: > On 9/14/19 10:35 AM, Markus Armbruster wrote: >> Entity checking goes back to commit ac88219a6c "qapi: New QAPISchema >> intermediate representation", v2.5.0. It's designed to work as >> follows: QAPISchema.check() calls .check() for all the schema's >> entities. An entity's .check() recurses into another entity's >> .check() only if the C struct generated for the former contains the C >> struct generated for the latter (pointers don't count). This is used >> to detect "object contains itself". >> >> There are two instances of this: >> >> * An object's C struct contains its base's C struct >> >> QAPISchemaObjectType.check() calls self.base.check() >> >> * An object's C struct contains its variants' C structs >> >> QAPISchemaObjectTypeVariants().check calls v.type.check(). Since >> commit b807a1e1e3 "qapi: Check for QAPI collisions involving variant >> members", v2.6.0. >> > >> Sadly, this design has since eroded: >> > >> * A QAPISchemaEntity's .module becomes valid at .check(). This is >> because computing it needs info and schema.fname, and because array >> types get it from their element type instead. >> >> Make it a property just like .ifcond. > > Extra space. Will fix. >> Additionally, have QAPISchemaEntity.check() assert it gets called at >> most once, so the design invariant will stick this time. Neglecting >> that was entirely my fault. > > Lengthy explanation, but it makes sense. Writing the commit message was more work than writing the patch... >> >> Signed-off-by: Markus Armbruster >> --- >> scripts/qapi/common.py | 74 +++++++++++++++++++++++++++++------------- >> 1 file changed, 52 insertions(+), 22 deletions(-) >> > > Took me a bit longer to read this (and refresh myself on what > '@property' actually does in Python, but you're not the first user of it > in qemu), but it matches the commit message. > > Reviewed-by: Eric Blake Thanks!