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dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf13.hostedemail.com: domain of xhao@linux.alibaba.com designates 115.124.30.42 as permitted sender) smtp.mailfrom=xhao@linux.alibaba.com X-Rspam-User: X-HE-Tag: 1664509595-308256 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 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. > > > Thanks, > SJ > > [...]