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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B47FC433FE for ; Fri, 30 Sep 2022 18:04:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ABE786B0073; Fri, 30 Sep 2022 14:04:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A6D728D0002; Fri, 30 Sep 2022 14:04:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 934DB6B0075; Fri, 30 Sep 2022 14:04:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 8082C6B0073 for ; Fri, 30 Sep 2022 14:04:07 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 45A4840B68 for ; 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charset=UTF-8 Content-Transfer-Encoding: 8bit ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=V1R010OM; spf=pass (imf06.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664561045; a=rsa-sha256; cv=none; b=1jRNq7jd8WGO1L8I6OrdnskGND7WHknOtADhCh8OvvApRifoWRDzFEHjlQua7y2x1EI6nv 8UWjWij7hOOu2YudJYqZIuLUWR4KgBrMQbxSeLb0GIM4U+bf37qBTt82JM61UPtT0ujJ6y XwUoEF41C6ZmRU9fYhNwMjx97/f2xPo= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664561045; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KDou48b+VqVXZox2Z42jOtogm/emxrNyI+XmRNDK80o=; b=n9N//p5Pk7BzWVAtKnlccbnvzN8ScvS7BskYECFImf+bHOzaUpaY6xgiT1ZAVdXW2WRolt KyINO0yfjg+W+OVLGYwPnF+58/FKOcXVcMCKwJ+SyaYxYxluiNB5duF1ejtcbN0PQ3Iv5M IQIHZMwEA/4qGU8fiKArh2jWPDh3N3Y= X-Stat-Signature: owmn6gqim634zikkprtrz3f6mb3xi7n3 X-Rspamd-Queue-Id: CD571180010 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=V1R010OM; spf=pass (imf06.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1664561045-99160 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Xin, On Fri, 30 Sep 2022 11:46:26 +0800 haoxin wrote: > Hi SJ, > > 在 2022/9/22 上午12:41, SeongJae Park 写道: > > Hi Xin, > > > > On Wed, 21 Sep 2022 11:49:42 +0800 Xin Hao wrote: > > > >> In damon/sysfs.c file, we use 'container_of' macro to get > >> damon_sysfs_xxx struct instances, but i think it has a little > >> inconvenience, because we have to pass three arguments to > >> 'container_of', and the codes also look a bit long, so there i add a > >> 'DAMON_OBJ' macro, you just need to pass one arguments, then you can get > >> the right damon_sysfs_xxx struct instance. > > Thank you always for your helps and efforts, but I have some comments below. > > > >> Signed-off-by: Xin Hao > >> --- > >> include/linux/damon.h | 7 ++ > >> mm/damon/sysfs.c | 230 +++++++++++++++++------------------------- > >> 2 files changed, 102 insertions(+), 135 deletions(-) > >> > >> diff --git a/include/linux/damon.h b/include/linux/damon.h > >> index e7808a84675f..a3b577677caa 100644 > >> --- a/include/linux/damon.h > >> +++ b/include/linux/damon.h > >> @@ -24,6 +24,13 @@ static inline unsigned long damon_rand(unsigned long l, unsigned long r) > >> return l + prandom_u32_max(r - l); > >> } > >> > >> +/* > >> + * Get damon_sysfs_xxx relative struct instance. > >> + */ > >> +#define DAMON_OBJ(_type) ({ \ > >> + const typeof(((struct _type *)0)->kobj)*__mptr = (kobj); \ > >> + (struct _type *)((char *)__mptr - offsetof(struct _type, kobj)); }) > >> + > > So, this macro assumes two implicit rules. > > 1. The caller would have a relevant 'struct kobject *' variable called 'kobj', > > and > > 2. The '_type' would have the field 'kobj'. > > > > I think the implicit rules could make some people confused, so would be better > > to be well documented. Even though those are well documented, I think it > > cannot intuitively read by everyone. Making the name better self-explaining > > might help, but then the length of the code would be not so different. > > > > So IMHO, this change makes the code a little bit shorter but unclear to > > understand what it does. And at least to my humble eyes, use of > > 'container_of()' makes the code a little bit more verbose, but clear to > > understand. I have no idea how we can make this code shorter while keeping it > > still easily understandable, and I think the level of verboseness is acceptable > > for the readability. So Nack at the moment, sorry. > > I really feel the need to do that， how about keep it in the sysfs.c > file, and change it like this： > > #define DAMON_OBJ(_struct) container_of(kobj, struct _struct, kobj) > > it will feel easy to understand and made sense. I don't think this is enough, at least for my humble eyes. My questions for better self-explaining name and removing the implicit rules are not answered. After all, I don't think the usage of container_of() is a real problem, though we might always have rooms for improvement. Thanks, SJ [...]