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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 054E7C433DF for ; Wed, 19 Aug 2020 13:30:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C26012067C for ; Wed, 19 Aug 2020 13:30:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597843822; bh=c/KIC1N+AThogXaPD4LYqtNhwTUgeFy5H658qfX3o6Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=2Q+zsdSDFHPLQk0looNICRzH/x8aUBftiSRqt79WMjvqfAvw7ngX3ywvoDsLxXC1x TtkQjYoJjXqEHZfjrt0coEzSsVvnGr288G7gpUrWomsBGAtls5O5KUBkmVikCtw3gi VETTotQOtNUNaiU4AGjscjBxujQqrPf0lxj7yGbI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728028AbgHSNaV (ORCPT ); Wed, 19 Aug 2020 09:30:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:41806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726752AbgHSNaT (ORCPT ); Wed, 19 Aug 2020 09:30:19 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 42672205CB; Wed, 19 Aug 2020 13:30:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597843817; bh=c/KIC1N+AThogXaPD4LYqtNhwTUgeFy5H658qfX3o6Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ybzJlclj7PKty/unc+4cb9Wd4WHHmVOSQ6smTxURwMsk2udx7+cwI/ct/VWqBRcaK TPHq+CA3SbHrkQu/Yr3Og03gF7ak5urBzCx3tlqFTNnNw+aON11BMaSWgLTxyquPrd 2nUrrz+cKds/3opgas5LKByGC0micQy3OPDbdyF4= Date: Wed, 19 Aug 2020 15:30:39 +0200 From: Greg KH To: Jens Axboe Cc: ulf.hansson@linaro.org, jassisinghbrar@gmail.com, s.hauer@pengutronix.de, manohar.vanga@gmail.com, airlied@linux.ie, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, James Bottomley , linux1394-devel@lists.sourceforge.net, anton.ivanov@cambridgegreys.com, devel@driverdev.osuosl.org, linux-s390@vger.kernel.org, maximlevitsky@gmail.com, richard@nod.at, deller@gmx.de, linux-atm-general@lists.sourceforge.net, 3chas3@gmail.com, linux-input@vger.kernel.org, kuba@kernel.org, mporter@kernel.crashing.org, jdike@addtoit.com, Kees Cook , oakad@yahoo.com, intel-gfx@lists.freedesktop.org, linux-um@lists.infradead.org, linux-block@vger.kernel.org, broonie@kernel.org, openipmi-developer@lists.sourceforge.net, mitch@sfgoth.com, linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, martyn@welchs.me.uk, dmitry.torokhov@gmail.com, linux-mmc@vger.kernel.org, Allen Pais , linux-spi@vger.kernel.org, alex.bou9@gmail.com, Allen Pais , stefanr@s5r6.in-berlin.de, daniel@ffwll.ch, sre@kernel.org, linux-ntb@googlegroups.com, Romain Perier , shawnguo@kernel.org, davem@davemloft.net Subject: Re: [PATCH] block: convert tasklets to use new tasklet_setup() API Message-ID: <20200819133039.GA3192753@kroah.com> References: <20200817091617.28119-2-allen.cryptic@gmail.com> <202008171228.29E6B3BB@keescook> <161b75f1-4e88-dcdf-42e8-b22504d7525c@kernel.dk> <202008171246.80287CDCA@keescook> <1597780833.3978.3.camel@HansenPartnership.com> <20200819131158.GA2591006@kroah.com> <4f5a225d-460f-978f-e3cf-3f505140a515@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4f5a225d-460f-978f-e3cf-3f505140a515@kernel.dk> Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Wed, Aug 19, 2020 at 07:17:19AM -0600, Jens Axboe wrote: > On 8/19/20 6:11 AM, Greg KH wrote: > > On Wed, Aug 19, 2020 at 07:00:53AM -0600, Jens Axboe wrote: > >> On 8/18/20 1:00 PM, James Bottomley wrote: > >>> On Mon, 2020-08-17 at 13:02 -0700, Jens Axboe wrote: > >>>> On 8/17/20 12:48 PM, Kees Cook wrote: > >>>>> On Mon, Aug 17, 2020 at 12:44:34PM -0700, Jens Axboe wrote: > >>>>>> On 8/17/20 12:29 PM, Kees Cook wrote: > >>>>>>> On Mon, Aug 17, 2020 at 06:56:47AM -0700, Jens Axboe wrote: > >>>>>>>> On 8/17/20 2:15 AM, Allen Pais wrote: > >>>>>>>>> From: Allen Pais > >>>>>>>>> > >>>>>>>>> In preparation for unconditionally passing the > >>>>>>>>> struct tasklet_struct pointer to all tasklet > >>>>>>>>> callbacks, switch to using the new tasklet_setup() > >>>>>>>>> and from_tasklet() to pass the tasklet pointer explicitly. > >>>>>>>> > >>>>>>>> Who came up with the idea to add a macro 'from_tasklet' that > >>>>>>>> is just container_of? container_of in the code would be > >>>>>>>> _much_ more readable, and not leave anyone guessing wtf > >>>>>>>> from_tasklet is doing. > >>>>>>>> > >>>>>>>> I'd fix that up now before everything else goes in... > >>>>>>> > >>>>>>> As I mentioned in the other thread, I think this makes things > >>>>>>> much more readable. It's the same thing that the timer_struct > >>>>>>> conversion did (added a container_of wrapper) to avoid the > >>>>>>> ever-repeating use of typeof(), long lines, etc. > >>>>>> > >>>>>> But then it should use a generic name, instead of each sub-system > >>>>>> using some random name that makes people look up exactly what it > >>>>>> does. I'm not huge fan of the container_of() redundancy, but > >>>>>> adding private variants of this doesn't seem like the best way > >>>>>> forward. Let's have a generic helper that does this, and use it > >>>>>> everywhere. > >>>>> > >>>>> I'm open to suggestions, but as things stand, these kinds of > >>>>> treewide > >>>> > >>>> On naming? Implementation is just as it stands, from_tasklet() is > >>>> totally generic which is why I objected to it. from_member()? Not > >>>> great with naming... But I can see this going further and then we'll > >>>> suddenly have tons of these. It's not good for readability. > >>> > >>> Since both threads seem to have petered out, let me suggest in > >>> kernel.h: > >>> > >>> #define cast_out(ptr, container, member) \ > >>> container_of(ptr, typeof(*container), member) > >>> > >>> It does what you want, the argument order is the same as container_of > >>> with the only difference being you name the containing structure > >>> instead of having to specify its type. > >> > >> Not to incessantly bike shed on the naming, but I don't like cast_out, > >> it's not very descriptive. And it has connotations of getting rid of > >> something, which isn't really true. > > > > I agree, if we want to bike shed, I don't like this color either. > > > >> FWIW, I like the from_ part of the original naming, as it has some clues > >> as to what is being done here. Why not just from_container()? That > >> should immediately tell people what it does without having to look up > >> the implementation, even before this becomes a part of the accepted > >> coding norm. > > > > Why are people hating on the well-known and used container_of()? > > > > If you really hate to type the type and want a new macro, what about > > 'container_from()'? (noun/verb is nicer to sort symbols by...) > > > > But really, why is this even needed? > > container_from() or from_container(), either works just fine for me > in terms of naming. > > I think people are hating on it because it makes for _really_ long > lines, and it's arguably cleaner/simpler to just pass in the pointer > type instead. Then you end up with lines like this: > > struct request_queue *q = > container_of(work, struct request_queue, requeue_work.work); > > But I'm not the one that started this addition of from_tasklet(), my > objection was adding a private macro for something that should be > generic functionality. Agreed. > Hence I think we either need to provide that, or > tell the from_tasklet() folks that they should just use container_of(). Also agreed, thanks. greg k-h