From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH 25/25] rte_eal_init: add info about rte_errno codes Date: Mon, 30 Jan 2017 21:19:29 +0100 Message-ID: <2880962.uYJx3WqeFl@xps13> References: <1485529023-5486-1-git-send-email-aconole@redhat.com> <20170127093729.5cef9138@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev@dpdk.org, Stephen Hemminger , Bruce Richardson To: Aaron Conole , adrien.mazarguil@6wind.com Return-path: Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48]) by dpdk.org (Postfix) with ESMTP id C27B03237 for ; Mon, 30 Jan 2017 21:19:31 +0100 (CET) Received: by mail-wm0-f48.google.com with SMTP id c85so230902002wmi.1 for ; Mon, 30 Jan 2017 12:19:31 -0800 (PST) In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 2017-01-30 13:38, Aaron Conole: > Stephen Hemminger writes: > > Bruce Richardson wrote: > >> On Fri, Jan 27, 2017 at 08:33:46AM -0800, Stephen Hemminger wrote: > >> > Why use rte_errno? > >> > Most DPDK calls just return negative value on error which > >> > corresponds to error number. > >> > Are you trying to keep ABI compatibility? Doesn't make sense > >> > because before all these > >> > errors were panic's no working application is going to care. > >> > >> Either will work, but I actually prefer this way. I view using rte_errno > >> to be better as it can work in just about all cases, including with > >> functions which return pointers. This allows you to have a standard > >> method across all functions for returning error codes, and it only > >> requires a single sentinal value to indicate error, rather than using a > >> whole range of values. > > > > The problem is DPDK is getting more inconsistent on how this is done. > > As long as error returns are always same as kernel/glibc errno's it really doesn't > > matter much which way the value is returned from a technical point of view > > but the inconsistency is sure to be a usability problem and source of errors. > > I am using rte_errno here because I assumed it was the preferred > method. In fact, looking at some recently contributed modules (for > instance pdump), it seems that folks are using it. > > I'm not really sure the purpose of having rte_errno if it isn't used, so > it'd be helpful to know if there's some consensus on reflecting errors > via this variable, or on returning error codes. Whichever is the more > consistent with the way the DPDK project does things, I'm game :). I think we can use both return value and rte_errno. We could try to enforce rte_errno as mandatory everywhere. Adrien did the recent rte_flow API. Please Adrien, could you give your thought?