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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 46377C47096 for ; Sun, 6 Jun 2021 09:36:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D0026136D for ; Sun, 6 Jun 2021 09:36:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230084AbhFFJ3h (ORCPT ); Sun, 6 Jun 2021 05:29:37 -0400 Received: from mail-pj1-f52.google.com ([209.85.216.52]:39640 "EHLO mail-pj1-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhFFJ3g (ORCPT ); Sun, 6 Jun 2021 05:29:36 -0400 Received: by mail-pj1-f52.google.com with SMTP id o17-20020a17090a9f91b029015cef5b3c50so10031415pjp.4 for ; Sun, 06 Jun 2021 02:27:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=9hJszFq4lHbv1ND+qGe92RXy6gvvhI7dS9USahuU+98=; b=Vt3+cyZRJXGj6xpBlOINayeqRQyPymvqKkEkTi8r2G35aqYVZ5kDrQ9wz76UPIKp1O J/GUI71fJWta4TBwyCyzp1772WWL+Jc4O79foJqWuLVazVO6UUCvPhwIzHmkKXsd5rtu cQlEr/WOLcKrOLrd9pySXBySDSwgLRqI0bMVfUO1WnSkau36v/duvOfIkU7KbAlAawkw 6yrPADea992BdvvmISJxGS3Tq8RbTCc/+Xoe9GHqB+2wYT8aCGV8uuRZX0kwHw8C9vO/ QnfCJ4ohQ42XkUqnhwtPKT2tFtyQLH22o32nvPbtQ/pL4WuE8+fXteX2xvPyfELGzElv yVrA== 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:references :mime-version:content-disposition:in-reply-to; bh=9hJszFq4lHbv1ND+qGe92RXy6gvvhI7dS9USahuU+98=; b=HfDAJbok5VYQBLDD2jVow4vwz7P8XNAm9SBq9F6yZPpsBQJtQ6VqyUYTvMQJdQQJjc R/pnYMHw4mCGy3I3s8wwl4+U1am/ZQ9O68jE6a4wBvRBbmcaOr6mda77XRLFKn9ltoLT 2dgDaaaemuOeFk+l52ABvb742ZtgqyI7xvf+A2jRPU99L6Ci+D6SMJ0cr0q0vseeCdEI XOQku8D80Gi8nHwARwQpKdjVmLmEjr2Z9mWU8g8YlY5s+okmvu3vKYylEMzzxA9XdwwW I/CP1Sgyh4ceCg4BZ4L+4tJhrmEfDbzwmdcDb0y8jl9rveUwcH6gwLJtV0It1qCOfG0O JC/A== X-Gm-Message-State: AOAM533tKBsh7xdKCNs1PNi0akGObnXFAnPj/HgSGCaErOvqf03rWhiE QeSZPMXKOqpOQXt+x7Q5yK8= X-Google-Smtp-Source: ABdhPJzRFNHBngQCYf1/triH9Yxq3zROcJpdkjGA9Iwn69RR5HN2xm2Uw5zFqa1dC0DF99WdlmRoMA== X-Received: by 2002:a17:90a:be0b:: with SMTP id a11mr13647302pjs.197.1622971606863; Sun, 06 Jun 2021 02:26:46 -0700 (PDT) Received: from ojas ([2405:204:130d:e843:24e:5eab:4be9:d84d]) by smtp.gmail.com with ESMTPSA id gn4sm9047526pjb.16.2021.06.06.02.26.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Jun 2021 02:26:46 -0700 (PDT) Date: Sun, 6 Jun 2021 14:56:32 +0530 From: Ojaswin Mujoo To: Stefan Wahren Cc: Dan Carpenter , nsaenz@kernel.org, gregkh@linuxfoundation.org, arnd@arndb.de, phil@raspberrypi.com, bcm-kernel-feedback-list@broadcom.com, linux-arm-kernel@lists.infradead.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: staging: vc04_services: Need suggestions on trying to fix sparse warning in vchiq_arm.c Message-ID: <20210606092601.GA6609@ojas> References: <20210601200513.GA10204@ojas> <20210601202307.GC1955@kadam> <20210602145000.GA3999@ojas> <9ba341f7-17fc-980d-a7a0-2293c75dcf92@i2se.com> <20210605072249.GA5967@ojas> <57aa6e2b-0267-664d-539a-e82000928101@i2se.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57aa6e2b-0267-664d-539a-e82000928101@i2se.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 05, 2021 at 10:41:17AM +0200, Stefan Wahren wrote: > Hi Ojaswin, > > Am 05.06.21 um 09:23 schrieb Ojaswin Mujoo: > > On Fri, Jun 04, 2021 at 08:13:06AM +0200, Stefan Wahren wrote: > >> Hi Ojaswin, > >> > >> Am 02.06.21 um 16:50 schrieb Ojaswin Mujoo: > >>> On Tue, Jun 01, 2021 at 11:23:07PM +0300, Dan Carpenter wrote: > >>>> The problem is not the Sparse warning, the problem is that this code is > >>>> a mess. It used to very clearly buggy and I reported the bug. I think > >>>> Arnd found the bug again independently and fixed it. > >>>> > >>>> A couple weeks ago Al Viro looked at this code. Here is his write up: > >>>> > >>>> https://www.spinics.net/lists/kernel/msg3952745.html > >>>> > >>>> It shouldn't take Al Viro dozens of pages of detailed analysis to try > >>>> figure out if the code is safe or not. Your idea silences the warning > >>>> but would make the code even more subtle and complicated. > >>>> > >>>> The right thing to do is to re-write the code to be simpler. > >>>> > >>>> regards, > >>>> dan carpenter > >>>> > >>> Thank you for the prompt reply and the link, it was very insightful. You > >>> are right, I was definitely going about this the wrong way and missing > >>> the larger picture. I'll spend some time trying to understand this > >>> codebase as I think that'd be a good start to understand how stuff works in > >>> the kernel (even though some of the things in this driver are anti patterns) > >>> and hopefully get some ideas on ways to clean this up. > >>> > >>> Anyways, thanks again for the help, cheers! > >> thanks for your interest in cleaning this up. Yes, it's not clear which > >> points on the TODO list are the lower hanging fruits. In case you don't > >> want to fix checkpatch issues, maybe you can look at points 8, 9, 10, 12 > >> and 13. Most of them require testing with a Raspberry Pi, but feel free > >> to ask if you have problems with it. > >> > >> Regards > >> Stefan > >> > > Got it, Task 10 (cdev to its own file) seems like a pretty good task to > > get started with. I'm planning to buy a Rpi 4 so I think I can run tests > > on that. > > okay, but the AFAIK the vchiq driver in the mainline kernel doesn't work > with Rpi 4 yet. The Raspberry Pi 3 B Plus is currently the recommend > devel platform, so you can test 32 and 64 bit kernel. > > Best regards Hey Stefan, Ahh got it. sure I can get a 3B+ instead, thanks for the heads up. > > > > > Thank you so much for the help, I'll get back incase I face any issues down > > the line. > > > > Regards, > > Ojaswin > > > >>> Ojaswin > >>> > >>> _______________________________________________ > >>> linux-arm-kernel mailing list > >>> linux-arm-kernel@lists.infradead.org > >>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > Regards, Ojaswin