On 12/19/2013 01:26 PM, Vasily Averin wrote: > On 12/19/2013 12:39 PM, Vladimir Davydov wrote: >> On 12/19/2013 12:17 PM, Vasily Averin wrote: >>> On 12/18/2013 05:16 PM, Vladimir Davydov wrote: >>>> --- a/mm/slab_common.c >>>> +++ b/mm/slab_common.c >>>> @@ -176,8 +176,9 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size, >>>> get_online_cpus(); >>>> mutex_lock(&slab_mutex); >>>> >>>> - if (!kmem_cache_sanity_check(memcg, name, size) == 0) >>>> - goto out_locked; >>>> + err = kmem_cache_sanity_check(memcg, name, size); >>>> + if (err) >>>> + goto out_unlock; >>>> >>>> /* >>>> * Some allocators will constraint the set of valid flags to a subset >>> Theoretically in future kmem_cache_sanity_check() can return positive value. >>> Probably it's better to check (err < 0) in caller ? >> Hmm, why? What information could positive retval carry here? We have >> plenty of places throughout the code where we check for (err), not >> (err<0), simply because it looks clearer, e.g. look at >> __kmem_cache_create() calls. If it returns a positive value one day, we >> will have to parse every place where it's called. Anyway, if someone >> wants to change a function behavior, he must check every place where >> this function is called and fix them accordingly. > I believe expected semantic of function -- return negative in case of error. > So correct error cheek should be (err < 0). > (err) check is semantically incorrect, and it can lead to troubles in future. You are free to use the "correct" check then, but making everyone do so would be too painful ;-) linux-tip$ grep -rI '^\s*if (err)' . | wc -l 13631 linux-tip$ grep -rI '^\s*if (err\s*<\s*0)' . | wc -l 5449 Thanks. -- 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>