From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965660AbcA1OiL (ORCPT ); Thu, 28 Jan 2016 09:38:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54514 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751635AbcA1OiI (ORCPT ); Thu, 28 Jan 2016 09:38:08 -0500 Date: Thu, 28 Jan 2016 09:38:07 -0500 From: Jarod Wilson To: Eric Dumazet Cc: linux-kernel@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jiri Pirko , Daniel Borkmann , Tom Herbert , Jay Vosburgh , Veaceslav Falico , Andy Gospodarek , netdev@vger.kernel.org Subject: Re: [PATCH net 0/4] net: add rx_unhandled stat counter Message-ID: <20160128143806.GE59058@redhat.com> References: <1453489882-57948-1-git-send-email-jarod@redhat.com> <1453926098-40181-1-git-send-email-jarod@redhat.com> <1453928987.20722.29.camel@edumazet-glaptop2.roam.corp.google.com> <20160128060215.GB59058@redhat.com> <20160128061808.GD59058@redhat.com> <1453986002.7627.20.camel@edumazet-glaptop2.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1453986002.7627.20.camel@edumazet-glaptop2.roam.corp.google.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 28, 2016 at 05:00:02AM -0800, Eric Dumazet wrote: > On Thu, 2016-01-28 at 01:18 -0500, Jarod Wilson wrote: > > > Or not. Now I remember why I added that in the first place: > > > > In file included from ./arch/x86/include/asm/uaccess.h:7:0, > > from net/core/dev.c:75: > > net/core/dev.c: In function 'netdev_stats_to_stats64': > > include/linux/compiler.h:484:20: error: call to '__compiletime_assert_7263' declared with attribute error: BUILD_BUG_ON failed: sizeof(*stats64) != sizeof(*netdev_stats) > > prefix ## suffix(); \ > > ^ > > > > Things are actually hard-wired to require that addition at the moment, or > > you get the above build failure. Not sure if it's safe to remove that > > BUILD_BUG_ON() yet, haven't looked closely, it's past my bed time. :) > > > > This was done for the transition from "unsigned long" to "u64", which is > a nop on 64bit arches. > > But as we do not need to be compatible, since no linux kernel in the > past had this new field in struct net_device_stats, > > and we do not need to add this new field as it is only accessed from > core networking stack [1], you need to adapt this helper. Something like this then: diff --git a/net/core/dev.c b/net/core/dev.c index 82334c6..2ca3eab 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -7262,15 +7262,16 @@ void netdev_run_todo(void) void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64, const struct net_device_stats *netdev_stats) { + memset(stats64, 0, sizeof(*stats64)); #if BITS_PER_LONG == 64 - BUILD_BUG_ON(sizeof(*stats64) != sizeof(*netdev_stats)); + BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats)); memcpy(stats64, netdev_stats, sizeof(*stats64)); #else size_t i, n = sizeof(*stats64) / sizeof(u64); const unsigned long *src = (const unsigned long *)netdev_stats; u64 *dst = (u64 *)stats64; - BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) != + BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) > sizeof(*stats64) / sizeof(u64)); for (i = 0; i < n; i++) dst[i] = src[i]; Compiles locally w/o that net_device_stats addition, seems sane to me. -- Jarod Wilson jarod@redhat.com