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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 212E4C433E0 for ; Tue, 9 Jun 2020 21:29:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F350F2072F for ; Tue, 9 Jun 2020 21:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728005AbgFIV3G (ORCPT ); Tue, 9 Jun 2020 17:29:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726888AbgFIV3F (ORCPT ); Tue, 9 Jun 2020 17:29:05 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBDE1C05BD1E for ; Tue, 9 Jun 2020 14:29:05 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 74C7E127A7CE6; Tue, 9 Jun 2020 14:29:04 -0700 (PDT) Date: Tue, 09 Jun 2020 14:29:01 -0700 (PDT) Message-Id: <20200609.142901.3888767961952002.davem@davemloft.net> To: lorenzo@kernel.org Cc: netdev@vger.kernel.org, thomas.petazzoni@bootlin.com, lorenzo.bianconi@redhat.com, brouer@redhat.com Subject: Re: [PATCH net] net: mvneta: do not redirect frames during reconfiguration From: David Miller In-Reply-To: References: X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 09 Jun 2020 14:29:04 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Lorenzo Bianconi Date: Tue, 9 Jun 2020 00:02:39 +0200 > Disable frames injection in mvneta_xdp_xmit routine during hw > re-configuration in order to avoid hardware hangs > > Fixes: b0a43db9087a ("net: mvneta: add XDP_TX support") > Signed-off-by: Lorenzo Bianconi Looking around, I wonder if the fundamental difference from the normal TX path is that the XDP path doesn't use the TXQ enable/disable machinery and checks like the normal ndo_start_xmit() paths do. And that's why only the XDP path has this issue. I'll apply this, so that the bug is fixed, but note that I consider this kind of change adding a new flags mask and one state bit to solve a problem to be ultimately inelegant and ususally pointing out a more fundamental issue. Thank you.