Re: [PATCH 04/12] kasan: clean up setting free info in kasan_slab_free

[Marco Elver]

On Mon, Feb 01, 2021 at 08:43PM +0100, Andrey Konovalov wrote:
> Put kasan_stack_collection_enabled() check and kasan_set_free_info()
> calls next to each other.
> 
> The way this was previously implemented was a minor optimization that
> relied of the the fact that kasan_stack_collection_enabled() is always
> true for generic KASAN. The confusion that this brings outweights saving
> a few instructions.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

> ---
>  mm/kasan/common.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index a7eb553c8e91..086bb77292b6 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -350,13 +350,11 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
>  
>  	kasan_poison(object, cache->object_size, KASAN_KMALLOC_FREE);
>  
> -	if (!kasan_stack_collection_enabled())
> -		return false;
> -
>  	if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
>  		return false;
>  
> -	kasan_set_free_info(cache, object, tag);
> +	if (kasan_stack_collection_enabled())
> +		kasan_set_free_info(cache, object, tag);
>  
>  	return kasan_quarantine_put(cache, object);
>  }
> -- 
> 2.30.0.365.g02bc693789-goog
>