Return-path: Received: from mail-qt0-f196.google.com ([209.85.216.196]:44439 "EHLO mail-qt0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726970AbeINAbK (ORCPT ); Thu, 13 Sep 2018 20:31:10 -0400 Date: Thu, 13 Sep 2018 16:20:14 -0300 From: Marcelo Ricardo Leitner To: Michal Kubecek Cc: Johannes Berg , linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 1/2] netlink: add NLA_REJECT policy type Message-ID: <20180913192014.GE4590@localhost.localdomain> (sfid-20180913_212024_327663_5A0FBFC8) References: <20180913084603.7979-1-johannes@sipsolutions.net> <20180913104955.GE29691@unicorn.suse.cz> <1536837915.4160.1.camel@sipsolutions.net> <20180913120554.GG29691@unicorn.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180913120554.GG29691@unicorn.suse.cz> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Sep 13, 2018 at 02:05:54PM +0200, Michal Kubecek wrote: > On Thu, Sep 13, 2018 at 01:25:15PM +0200, Johannes Berg wrote: > > On Thu, 2018-09-13 at 12:49 +0200, Michal Kubecek wrote: > > > > > > if (type > 0 && type <= maxtype) { > > > > if (policy) { > > > > - err = validate_nla(nla, maxtype, policy); > > > > + err = validate_nla(nla, maxtype, policy, > > > > + extack); > > > > if (err < 0) { > > > > - NL_SET_ERR_MSG_ATTR(extack, nla, > > > > - "Attribute failed policy validation"); > > > > + NL_SET_BAD_ATTR(extack, nla); > > > > + if (extack && !extack->_msg) > > > > + NL_SET_ERR_MSG(extack, > > > > + "Attribute failed policy validation"); > > > > goto errout; > > > > } > > > > } > > > > -- > > > > > > Technically, this would change the outcome when nla_parse() is called > > > with extack->_msg already set nad validate_nla() fails on something else > > > than NLA_REJECT; it will preserve the previous message in such case. > > > But I don't think this is a serious problem. > > > > Yes, that's true. I looked at quite a few of the setters just now (there > > are ~500 already, wow!), and they all set & return, so this shouldn't be > > an issue. > > In ethtool (work in progress) I sometimes use extack message for > non-fatal warnings but AFAICS never before parsing the userspace > request (actually always shortly before returning). So I don't have > a problem with it. Considering we can only report 1 message, it should be okay to drop the previous message in favor of the new one, which is either a critical one or just another non-fatal one. Marcelo