On Wed 26-07-17 15:03:32, Andrew Morton wrote: > On Wed, 26 Jul 2017 14:49:14 -0700 Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote: > > > 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@xxxxxxxxxxxx> 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? > > I suspect so - the current implementation is denying reality and your > original proposal is a bit of a fudge. But I'll await input from the > memcg peeps. well, those enums do not help type safety much I am afraid so turining the idx to int sounds like a more preferable way to me. Johannes? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
