From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke 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 Message-ID: <20170726214914.GA84665@google.com> References: <20170726192356.18420-1-mka@chromium.org> <20170726142309.ac40faf5eb99568e6edb064c@linux-foundation.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=7NhNkWGcWAqn28wYUp7MIYXYXThyaObAuJxnZxDZa54=; b=ilLv7rHrUESJ2GARFPi4382WoWKKHRBP1osZbKQvfmrs+RrMzbEDVLRgpHIOIL27qw 4prZpH01VCvW8RAumpJckfZKqUvnjpVwArdwfToood4crL04TXLSHBvitWrtYI4Op4vp UR17pUv0oAO+X7A/n7bZUcL3lWIALkX0HmdB4= Content-Disposition: inline In-Reply-To: <20170726142309.ac40faf5eb99568e6edb064c@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Doug Anderson 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 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org