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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0B85ECE596 for ; Thu, 10 Oct 2019 04:25:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9CAFB218AC for ; Thu, 10 Oct 2019 04:25:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="eZn5FosL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726201AbfJJEZG (ORCPT ); Thu, 10 Oct 2019 00:25:06 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:32915 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725822AbfJJEZG (ORCPT ); Thu, 10 Oct 2019 00:25:06 -0400 Received: by mail-pl1-f196.google.com with SMTP id d22so2146375pls.0 for ; Wed, 09 Oct 2019 21:25:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=F2mWN6iONW+mLLRJyrXLX3Mqwxx68njinFB093kEhkw=; b=eZn5FosLXe+fiRRmpB6ryaaoYD1tGLkVUMy4O2wDqlMSTpoyb/ivArjB+DV5gr7+Sf 9zj1ab4evn+7oQJEETVg0tHAr4v+PSKgH/xW2+3kWA8RmvdAnDX+f48hQhhhXZv77+tB vRmd4YNclxFP2s+9bLvWEn0wYs1jQzjt/u3IWYqKo5annaJKePlMXFdfGJqwWUSuTgeL T40rWhEFQYaXcVdTio+3mcmH7+pc4yq+hiV/jj+gEmfB3N7LVsKMZocFt3kO4ydEC7c2 YWhGn9507jTzbrpc8qxWa5UXCY8u/Y7U8MjejDrcMISQQ2LjXT8MpR2HtX+tbsGuRXBE QKTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=F2mWN6iONW+mLLRJyrXLX3Mqwxx68njinFB093kEhkw=; b=cKpP6fJJp+F0crL+WKQzCrjjeEYF/T0FyeNMF0uK4GlNIBhQcDIn68/9axlS/akQVY 6doCi5+b2ao2LOlxFQzVqeHcH6mhDZP+SLCVNSUh5xgBCS4J2sNXGvcxd+EMMo6aRu/F j8FGwAOAtDgqx/KruKGsapPXgp+mLJ8vY+z21zCn4YmaUl4A8HOxwvaV2ToCNeqvA4Hl /0ZUDFoxXBC3OU2GLGpYfI2+STPfxtsWSNVBUglanGcRW3aiSArLth9sxE2USZvM5CkY pVehx6g6mqDtAJGfHZd6/N/4SwgbtxfcYjH5Yws0OudQxFl/Ymw1YAJ7Ud8D6ZlvqOHl +Miw== X-Gm-Message-State: APjAAAVttshi0zCmU8IEcImZfcJX1f+4tjhVUVgPYcXrrYVcJaOxpIg4 g2/rhNZtrvc42yw6ZRaNYmILUw== X-Google-Smtp-Source: APXvYqynM/govpFUXiDmKtrtBuM+YvQonis/gzdNY0zb3g+8xM5GSCV5XpIVAUZNAKVdywvpRG05Eg== X-Received: by 2002:a17:902:bc4c:: with SMTP id t12mr6816220plz.53.1570681505624; Wed, 09 Oct 2019 21:25:05 -0700 (PDT) Received: from cakuba.netronome.com (c-73-202-202-92.hsd1.ca.comcast.net. [73.202.202.92]) by smtp.gmail.com with ESMTPSA id k93sm7601550pjh.3.2019.10.09.21.25.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Oct 2019 21:25:05 -0700 (PDT) Date: Wed, 9 Oct 2019 21:24:51 -0700 From: Jakub Kicinski To: Eric Dumazet Cc: Pablo Neira Ayuso , Jozsef Kadlecsik , Florian Westphal , netfilter-devel@vger.kernel.org, netdev , Eric Dumazet , syzbot , Jozsef Kadlecsik Subject: Re: [PATCH net] netfilter: conntrack: avoid possible false sharing Message-ID: <20191009212451.0522979f@cakuba.netronome.com> In-Reply-To: <20191009161913.18600-1-edumazet@google.com> References: <20191009161913.18600-1-edumazet@google.com> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Wed, 9 Oct 2019 09:19:13 -0700, Eric Dumazet wrote: > As hinted by KCSAN, we need at least one READ_ONCE() > to prevent a compiler optimization. > > More details on : > https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance > > [...] > > Fixes: cc16921351d8 ("netfilter: conntrack: avoid same-timeout update") > Signed-off-by: Eric Dumazet > Reported-by: syzbot > Cc: Pablo Neira Ayuso > Cc: Jozsef Kadlecsik > Cc: Florian Westphal Applied, thank you. Not queuing for stable, please let me know if I should.