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 Received: from diktynna.open-mesh.org (diktynna.open-mesh.org [136.243.236.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0D53DCA5FF1 for ; Wed, 7 Oct 2026 12:16:11 +0000 (UTC) Received: from diktynna.open-mesh.org (localhost [IPv6:::1]) by diktynna.open-mesh.org (Postfix) with ESMTP id 22892842E0 for ; Wed, 07 Oct 2026 14:16:10 +0200 (CEST) ARC-Seal: i=2; cv=pass; a=rsa-sha256; d=open-mesh.org; s=20121; t=1791375370; b=0SJ1Q9wYAeVxINHexCSrT+pUbJp/m6er5gbK1vsqzmOfYnPuBiH9yLUo9BmzT6dDTf3Fr JW8X7MV8gmvT+9rkS6HGZyCUdpMUAWFaq7tI48nXgxDwBaXilq4UxOAYRq1V66qAvtajrj7 6DI1aO4dxL5rDhnPfvAqSBfCy/7qWpA= ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=open-mesh.org; s=20121; t=1791375370; h=from : sender : reply-to : subject : date : message-id : to : cc : mime-version : content-type : content-transfer-encoding : content-id : content-description : resent-date : resent-from : resent-sender : resent-to : resent-cc : resent-message-id : in-reply-to : references : list-id : list-help : list-unsubscribe : list-subscribe : list-post : list-owner : list-archive; bh=okgKi511OVkyEIVNzliggu3RNZafOgSP7vr21BH+y68=; b=ANyYWLSY8aS6l2A2LCgrp4VDgo6yJIiN9GZtrWAXMkymqwd5okZIOKRGy8FdkW8H6sqY0 gJY7/6gZGYBW651IcjKsiW2qJVhFXdwGcF9j2pOTD5C3huIMNbz7Zboski9XYgCDA3hP+Mr vaUaLOLO4W6yf0ASo2MvKqDJ5SEP2po= ARC-Authentication-Results: i=2; open-mesh.org; dkim=fail; arc=pass; dmarc=none Authentication-Results: open-mesh.org; dkim=fail; arc=pass; dmarc=none Received: from mail.aperture-lab.de (mail.aperture-lab.de [IPv6:2a01:4f8:c2c:665b::1]) by diktynna.open-mesh.org (Postfix) with ESMTPS id 7BAB1806E9 for ; Wed, 07 Oct 2026 14:15:49 +0200 (CEST) ARC-Seal: i=1; a=rsa-sha256; d=open-mesh.org; s=20121; cv=none; t=1791375359; b=vknQz6K3g+99uFH8vKX30EGD2UiqaWm4npHgyRJ47bMzeY5rGG0tYCzftk0Xiye6hoheUS D7MUaNT7HWkORO2HFAP8M+waFSvDyCHeiyBNSGNE2dJbgTQHn4PI6mqAIoHZX4vOkuEfYl iW70nlBnUZotTQIejCCbv+oVv8jEig4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=open-mesh.org; s=20121; t=1791375359; 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=okgKi511OVkyEIVNzliggu3RNZafOgSP7vr21BH+y68=; b=zd/s4wHZ26jJWd8u4Unn7GsDVf3S32t4Wbw4fFm0Uj1+WC7ecm8so+50Y6bY/khHX2GvRL KpdlkFXghG69P4GdwJvm+t62usl8Ln8veUgFdZwso0XZuyVyhn3YQtHIxpTmELeSjS+IB5 k/Mc+8eYecsD1E0TX/e/5v+8lfO0xWU= ARC-Authentication-Results: i=1; diktynna.open-mesh.org; dkim=none; dmarc=none; spf=pass (diktynna.open-mesh.org: domain of linus.luessing@c0d3.blue designates 2a01:4f8:c2c:665b::1 as permitted sender) smtp.mailfrom=linus.luessing@c0d3.blue Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 650D323237; Wed, 07 Oct 2026 14:15:45 +0200 (CEST) Date: Wed, 7 Oct 2026 14:15:44 +0200 From: Linus =?utf-8?Q?L=C3=BCssing?= To: Sven Eckelmann Cc: b.a.t.m.a.n@lists.open-mesh.org, sashiko-reviews@lists.linux.dev, marek.lindner@mailbox.org, sw@simonwunderlich.de, antonio@mandelbit.com Subject: Re: [batadv,v14 5/5] batman-adv: avoid superfluous DAT DHT_PUT additions to local DAT Message-ID: References: <5152412.GXAFRqVoOG@sven-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5152412.GXAFRqVoOG@sven-desktop> X-Last-TLS-Session-Version: TLSv1.3 Message-ID-Hash: FHVCNRJ6KQCOTCW3KE3MDRHHWKVD6ZAS X-Message-ID-Hash: FHVCNRJ6KQCOTCW3KE3MDRHHWKVD6ZAS X-MailFrom: linus.luessing@c0d3.blue X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; header-match-b.a.t.m.a.n.lists.open-mesh.org-0; header-match-b.a.t.m.a.n.lists.open-mesh.org-1; header-match-b.a.t.m.a.n.lists.open-mesh.org-2; header-match-b.a.t.m.a.n.lists.open-mesh.org-3; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, Oct 07, 2026 at 09:24:23AM +0200, Sven Eckelmann wrote: > On Wednesday, 7 October 2026 03:08:03 CEST Linus Lüssing wrote: > > > - [Medium] batadv: UAPI source compatibility breakage via reserved field rename > > > > I would have thought that for a field called "reserved" it would > > be clear that it'd be subject to change in the future. > > To play the devils advocate: But programs would still fail when they > manually initialize this field to 0. On the other hand I'm thinking they should have memset() the struct to zero in the first place, instead of manually setting a reserved field to 0. Similar to ioctl()'s for instance, where there too you should memset/zero the full struct, passed argument, I believe, instead of just zero'ing individual fields as there might be new fields getting appended in the future. Interestingly, include/uapi/linux/ethtool.h has an explicit note for this: ``` 26 /* Note on reserved space. 27 * Reserved fields must not be accessed directly by user space because 28 * they may be replaced by a different field in the future. They must 29 * be initialized to zero before making the request, e.g. via memset 30 * of the entire structure or implicitly by not being set in a structure 31 * initializer. 32 */ ``` Which we don't have in batadv_packet.h though. (So technically, someone could complain about such a rename because we don't have such a note?)