From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Schiller Subject: Re: [PATCH 1/2] wan/hdlc_x25: make lapb params configurable Date: Tue, 14 Jan 2020 14:33:51 +0100 Message-ID: <3b439730f93e29c9e823126b74c2fbd3@dev.tdt.de> References: <20200113124551.2570-1-ms@dev.tdt.de> <20200113055316.4e811276@cakuba> <83f60f76a0cf602c73361ccdb34cc640@dev.tdt.de> <20200114045149.4e97f0ac@cakuba> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200114045149.4e97f0ac@cakuba> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Jakub Kicinski Cc: khc@pm.waw.pl, davem@davemloft.net, linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org On 2020-01-14 13:51, Jakub Kicinski wrote: > On Tue, 14 Jan 2020 06:37:03 +0100, Martin Schiller wrote: >> >> diff --git a/include/uapi/linux/hdlc/ioctl.h >> >> b/include/uapi/linux/hdlc/ioctl.h >> >> index 0fe4238e8246..3656ce8b8af0 100644 >> >> --- a/include/uapi/linux/hdlc/ioctl.h >> >> +++ b/include/uapi/linux/hdlc/ioctl.h >> >> @@ -3,7 +3,7 @@ >> >> #define __HDLC_IOCTL_H__ >> >> >> >> >> >> -#define GENERIC_HDLC_VERSION 4 /* For synchronization with sethdlc >> >> utility */ >> >> +#define GENERIC_HDLC_VERSION 5 /* For synchronization with sethdlc >> >> utility */ >> > >> > What's the backward compatibility story in this code? >> >> Well, I thought I have to increment the version to keep the kernel >> code >> and the sethdlc utility in sync (like the comment says). > > Perhaps I chose the wrong place for asking this question, IOCTL code > was my real worry. I don't think this version number is validated so > I think bumping it shouldn't break anything? sethdlc validates the GENERIC_HDLC_VERSION at compile time. https://mirrors.edge.kernel.org/pub/linux/utils/net/hdlc/ Another question: Where do I have to send my patch for sethdlc to? > >> > The IOCTL handling at least looks like it may start returning errors >> > to existing user space which could have expected the parameters to >> > IF_PROTO_X25 (other than just ifr_settings.type) to be ignored. >> >> I could also try to implement it without incrementing the version by >> looking at ifr_settings.size and using the former defaults if the size >> doesn't match. > > Sounds good, thank you! OK, I will send a v2 of the patch.