On 12/19/2013 11:26 AM, 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.
I don't know what semantics you are referring to but a typical
convention in mm/*.c is to return zero on success and negative on error
but never positive numbers.
Looking at mm/slab_common.c, "if (err)" is the established convention so
using "if (err < 0)" just because is pointless here.
Pekka
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