From: Matthias Kaehlcke <mka@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, Doug Anderson <dianders@chromium.org>
Subject: Re: [PATCH] mm: memcontrol: Cast mismatched enum types passed to memcg state and event functions
Date: Wed, 26 Jul 2017 14:49:14 -0700 [thread overview]
Message-ID: <20170726214914.GA84665@google.com> (raw)
In-Reply-To: <20170726142309.ac40faf5eb99568e6edb064c@linux-foundation.org>
El Wed, Jul 26, 2017 at 02:23:09PM -0700 Andrew Morton ha dit:
> On Wed, 26 Jul 2017 12:23:56 -0700 Matthias Kaehlcke <mka@chromium.org> wrote:
>
> > In multiple instances enum values of an incorrect type are passed to
> > mod_memcg_state() and other memcg functions. Apparently this is
> > intentional, however clang rightfully generates tons of warnings about
> > the mismatched types. Cast the offending values to the type expected
> > by the called function. The casts add noise, but this seems preferable
> > over losing the typesafe interface or/and disabling the warning.
> >
> > ...
> >
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -576,7 +576,7 @@ static inline void __mod_lruvec_state(struct lruvec *lruvec,
> > if (mem_cgroup_disabled())
> > return;
> > pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
> > - __mod_memcg_state(pn->memcg, idx, val);
> > + __mod_memcg_state(pn->memcg, (enum memcg_stat_item)idx, val);
> > __this_cpu_add(pn->lruvec_stat->count[idx], val);
> > }
>
> __mod_memcg_state()'s `idx' arg can be either enum memcg_stat_item or
> enum memcg_stat_item. I think it would be better to just admit to
> ourselves that __mod_memcg_state() is more general than it appears, and
> change it to take `int idx'. I assume that this implicit cast of an
> enum to an int will not trigger a clang warning?
Sure, no warnings are raised for implicit casts from enum to
int.
__mod_memcg_state() is not the only function though, all these
functions are called with conflicting types:
memcg_page_state()
__mod_memcg_state()
mod_memcg_state()
count_memcg_events()
count_memcg_page_event()
memcg_sum_events()
Should we change all of them to reveice an int instead of an enum?
next prev parent reply other threads:[~2017-07-26 21:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-26 19:23 [PATCH] mm: memcontrol: Cast mismatched enum types passed to memcg state and event functions Matthias Kaehlcke
2017-07-26 21:23 ` Andrew Morton
2017-07-26 21:49 ` Matthias Kaehlcke [this message]
2017-07-26 22:03 ` Andrew Morton
2017-07-27 7:24 ` Michal Hocko
2017-07-27 14:17 ` Johannes Weiner
2017-07-27 19:46 ` Matthias Kaehlcke
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170726214914.GA84665@google.com \
--to=mka@chromium.org \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=dianders@chromium.org \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=vdavydov.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).