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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD274C04A95 for ; Wed, 28 Sep 2022 18:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234192AbiI1Sc6 (ORCPT ); Wed, 28 Sep 2022 14:32:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231650AbiI1Sc4 (ORCPT ); Wed, 28 Sep 2022 14:32:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9257375FE3 for ; Wed, 28 Sep 2022 11:32:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2FAD861F78 for ; Wed, 28 Sep 2022 18:32:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BCF6C433C1; Wed, 28 Sep 2022 18:32:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664389974; bh=V8yXMC4PFrm7TduLRrwEgvYf5CG++MMP/ATFWfpqRbE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=rvGZE0NbBzFsXhFeJoIzdnvvskxYzMONbCwZADtXLVMkL9M2oxcoMGq0jTLEBt9IA 9N5xzF1q4DyLCUReWnOZ+uix15Z91iHByBP1INQAv0GuCgppjAbybQYJJYU3CvX8TW XBzwDgEBKtvSjdj+53F6fLAWSOYNnDmItlzvbuyyxv1/WEJ9l3Xj3wZdYX64vKsZFf y63Y7OnYQoBs1pVXTB/mAXG7u8v10hLhfnEOxf+T1Miec5pbLGbawAgFscpdZN6QVu 7SPrBqU+4Vc7PeKYP9Au5tsNe4lbE2zje7dwIBfRmgjviPzd5Ynu5jRXrPMz209hT1 1K3DYEHPbmyDA== Date: Wed, 28 Sep 2022 11:32:53 -0700 From: Jakub Kicinski To: Edward Cree Cc: netdev@vger.kernel.org, linux-net-drivers@amd.com, davem@davemloft.net, pabeni@redhat.com, edumazet@google.com, habetsm.xilinx@gmail.com Subject: Re: [PATCH v2 net-next 3/6] sfc: optional logging of TC offload errors Message-ID: <20220928113253.1823c7e1@kernel.org> In-Reply-To: References: <20220928104426.1edd2fa2@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 28 Sep 2022 19:17:51 +0100 Edward Cree wrote: > > Because extack does not work somehow? > > Last I checked, flow rules coming from an indirect binding to a tunnel > netdev did not report the hw driver's extack (or even rc) back to the > user. > Also, extack can only contain fixed strings (netlink.h: "/* Currently > string formatting is not supported (due to the lack of an output > buffer.) */") which was a real problem for us. > > > Somehow you limitations are harder to debug that everyone else's so you > > need a private flag? :/ > > It's not about debugging the driver, it's about communicating the > limitations to the end user. Having TC rules mysteriously fail to be > offloaded with no indication of why is not a great UX :( Yes, but everyone has the same problem. > I couldn't see a way to handle this without vendor-specific ugliness, > but if you have a proposal I don't mind putting in some work to > implement it. I won't help with the indirect stuff, I fixed it once a while back already and it keeps getting broken. It must be a case of the extack not being plumbed thru, or people being conservative because the errors are not fatal, right? Solvable. The printf'ing? I recon something simple like adding a destructor for the message to the exack struct so you can allocate the message, or adding a small buffer in place (the messages aren't very long, usually) come to mind.