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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 3F3CCC6369E for ; Wed, 18 Nov 2020 16:27:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C00C52481C for ; Wed, 18 Nov 2020 16:27:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="dAHGsinR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727912AbgKRQ1C (ORCPT ); Wed, 18 Nov 2020 11:27:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:56780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbgKRQ1B (ORCPT ); Wed, 18 Nov 2020 11:27:01 -0500 Received: from kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net (unknown [163.114.132.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9752724818; Wed, 18 Nov 2020 16:26:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605716820; bh=d6fcYi77BXc0FDTlYdszbLc7LzeiPITJH4/OZIoT2Sg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dAHGsinRGFxYeHu9dwjrFUIo14FWc38Mv6mosYACM0CItOIG6P+Rylwmr8ZMzCW2v E+bR4pkNQ6SKYXvZAkFpHP+C+n65mHUjTlpEI35S5nbPWyz/eIgfV+kxSxpyrvw0Av L3lZOKAv8jyozkH11r5jtDatMK/yDwyIc4EFNIyQ= Date: Wed, 18 Nov 2020 08:26:58 -0800 From: Jakub Kicinski To: Peter Zijlstra Cc: Yunsheng Lin , davem@davemloft.net, linmiaohe@huawei.com, martin.varghese@nokia.com, pabeni@redhat.com, pshelar@ovn.org, fw@strlen.de, gnault@redhat.com, steffen.klassert@secunet.com, kyk.segfault@gmail.com, viro@zeniv.linux.org.uk, vladimir.oltean@nxp.com, edumazet@google.com, saeed@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com Subject: Re: [PATCH net-next] net: add in_softirq() debug checking in napi_consume_skb() Message-ID: <20201118082658.2aa41190@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> In-Reply-To: <20201118155757.GY3121392@hirez.programming.kicks-ass.net> References: <1603971288-4786-1-git-send-email-linyunsheng@huawei.com> <20201031153824.7ae83b90@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> <5b04ad33-1611-8d7b-8fec-4269c01ecab3@huawei.com> <20201102114110.4a20d461@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> <5bd6de52-b8e0-db6f-3362-862ae7b2c728@huawei.com> <20201118074348.3bbd1468@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> <20201118155757.GY3121392@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 18 Nov 2020 16:57:57 +0100 Peter Zijlstra wrote: > On Wed, Nov 18, 2020 at 07:43:48AM -0800, Jakub Kicinski wrote: > > > TBH the last sentence I wrote isn't clear even to me at this point ;D > > > > Maybe using just the macros from preempt.h - like this? > > > > #define lockdep_assert_in_softirq() \ > > do { \ > > WARN_ON_ONCE(__lockdep_enabled && \ > > (!in_softirq() || in_irq() || in_nmi()) \ > > } while (0) > > > > We know what we're doing so in_softirq() should be fine (famous last > > words). > > So that's not actually using any lockdep state. But if that's what you > need, I don't have any real complaints. Great, thanks! The motivation was to piggy back on lockdep rather than adding a one-off Kconfig knob for a check in the fast path in networking.