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 07EC2C25B50 for ; Fri, 20 Jan 2023 20:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229722AbjATU5O (ORCPT ); Fri, 20 Jan 2023 15:57:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229454AbjATU5M (ORCPT ); Fri, 20 Jan 2023 15:57:12 -0500 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85E824C0F0 for ; Fri, 20 Jan 2023 12:57:11 -0800 (PST) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4NzBS959vHz9v7HD for ; Sat, 21 Jan 2023 04:49:13 +0800 (CST) Received: from [10.81.223.78] (unknown [10.81.223.78]) by APP2 (Coremail) with SMTP id GxC2BwAH2F4GAMtjBPWwAA--.5651S2; Fri, 20 Jan 2023 21:56:48 +0100 (CET) Message-ID: Date: Fri, 20 Jan 2023 21:56:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: Internal vs. external barriers (was: Re: Interesting LKMM litmus test) To: paulmck@kernel.org Cc: Andrea Parri , Jonas Oberhauser , Peter Zijlstra , will , "boqun.feng" , npiggin , dhowells , "j.alglave" , "luc.maranget" , akiyks , dlustig , joel , urezki , quic_neeraju , frederic , Kernel development list References: <20230118211201.GL2948950@paulmck-ThinkPad-P17-Gen-1> <09f084d2-6128-7f83-b2a5-cbe236b1678d@huaweicloud.com> <20230119001147.GN2948950@paulmck-ThinkPad-P17-Gen-1> <0fae983b-2a7c-d44e-8881-53d5cc053f09@huaweicloud.com> <20230119184107.GT2948950@paulmck-ThinkPad-P17-Gen-1> <20230120035521.GA319650@paulmck-ThinkPad-P17-Gen-1> <126e32b7-caa7-0a1e-4589-885aef7c5a39@huaweicloud.com> <20230120153242.GE2948950@paulmck-ThinkPad-P17-Gen-1> From: Jonas Oberhauser In-Reply-To: <20230120153242.GE2948950@paulmck-ThinkPad-P17-Gen-1> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: GxC2BwAH2F4GAMtjBPWwAA--.5651S2 X-Coremail-Antispam: 1UD129KBjvJXoW7CFyUGFyDAryxJw4xWFWfKrg_yoW8Xr43pF W8tFZ8C34DJrWIvas3Kr40yF1fXw43twsxJry3G3y8Z345Xas3K3yfKayrZrZxCr13Kw4Y 9w4av39xAF4kZaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvSb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7Mxk0xIA0c2IE e2xFo4CEbIxvr21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxV Aqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a 6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6x kF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyUJwCI42IY6I8E87Iv 67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsGvfC2KfnxnUUI43 ZEXa7IUbG2NtUUUUU== X-CM-SenderInfo: 5mrqt2oorev25kdx2v3u6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/20/2023 4:32 PM, Paul E. McKenney wrote: > On Fri, Jan 20, 2023 at 01:51:01PM +0100, Jonas Oberhauser wrote: >> I'm not going to get it right today, am I? > Believe me, I know that feeling! Open-source development is therefore > an extremely good character-building exercise. At least that is what > I keep telling myself. ;-) "Calvin, go do something you hate! Being miserable builds character!" > >> +let srcu-rscs = ([Srcu-lock] ; (data ; [~ Srcu-unlock] ; rfe) * ; data ; >> [Srcu-unlock]) & loc >> >> I see now that I copied the format from your message but without realizing >> the original had a `|` where I have a `;`. >> I hope this version is finally right and perhaps more natural than the (data >> | rf) version, considering rf can't actually appear in most places and this >> more closely matches carry-dep;data. >> But of course feel free to use >> +let srcu-rscs = ([Srcu-lock] ; (data  | [~ Srcu-unlock] ; rf)+ ; >> [Srcu-unlock]) & loc >> instead if you prefer. > > The reason for favoring "rf" over "rfe" is the possibility of a litmus > test where the process containing the srcu_down_read() sometimes but > not always also has the matching srcu_up_read(). Perhaps a pair of "if" > statements control which process does the matching srcu_up_read(). If you put the redefinition of data early enough to affect this definition, the rfi option should be covered by the carry-dep in the redefinition of data, so I left it out. > And thank you!!! always ;-) jonas