Messages in this thread | | | Date | Wed, 26 Jul 2017 14:49:14 -0700 | From | Matthias Kaehlcke <> | Subject | Re: [PATCH] mm: memcontrol: Cast mismatched enum types passed to memcg state and event functions |
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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?
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