Re: [PATCH v6 2/6] init_on_alloc: Optimize static branches

Kees Cook
2021-03-15T22:15:50Z

On Mon, Mar 15, 2021 at 11:02:25AM -0700, Kees Cook wrote:
> diff --git a/mm/slab.h b/mm/slab.h
> index 076582f58f68..b0977d525c06 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -601,7 +601,8 @@ static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
>
> static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
> {
> - if (static_branch_unlikely(&init_on_alloc)) {
> + if (static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON,

Gah, this should be CONFIG_INIT_ON_ALLOC_DEFAULT_ON.

I'll see if there are any more comments before sending a v7...

-Kees

> + &init_on_alloc)) {
> if (c->ctor)
> return false;
> if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
> @@ -613,7 +614,8 @@ static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
>
> static inline bool slab_want_init_on_free(struct kmem_cache *c)
> {
> - if (static_branch_unlikely(&init_on_free))
> + if (static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON,
> + &init_on_free))
> return !(c->ctor ||
> (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)));
> return false;
> --
> 2.25.1
>

--
Kees Cook