Re: [PATCH v2 14/20] kasan, mm: rename kasan_poison_kfree

[Marco Elver <elver@google.com>]

On Tue, Nov 10, 2020 at 11:20PM +0100, Andrey Konovalov wrote:
> Rename kasan_poison_kfree() to kasan_slab_free_mempool() as it better
> reflects what this annotation does.

This function is again so simple, and now it seems it's mempool
specific, can't we just remove it and open-code it in mempool.c?

> No functional changes.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> Link: https://linux-review.googlesource.com/id/I5026f87364e556b506ef1baee725144bb04b8810
> ---
>  include/linux/kasan.h | 16 ++++++++--------
>  mm/kasan/common.c     | 16 ++++++++--------
>  mm/mempool.c          |  2 +-
>  3 files changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 779f8e703982..534ab3e2935a 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -177,6 +177,13 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned
>  	return false;
>  }
>  
> +void __kasan_slab_free_mempool(void *ptr, unsigned long ip);
> +static inline void kasan_slab_free_mempool(void *ptr, unsigned long ip)
> +{
> +	if (kasan_enabled())
> +		__kasan_slab_free_mempool(ptr, ip);
> +}
> +
>  void * __must_check __kasan_slab_alloc(struct kmem_cache *s,
>  				       void *object, gfp_t flags);
>  static inline void * __must_check kasan_slab_alloc(struct kmem_cache *s,
> @@ -217,13 +224,6 @@ static inline void * __must_check kasan_krealloc(const void *object,
>  	return (void *)object;
>  }
>  
> -void __kasan_poison_kfree(void *ptr, unsigned long ip);
> -static inline void kasan_poison_kfree(void *ptr, unsigned long ip)
> -{
> -	if (kasan_enabled())
> -		__kasan_poison_kfree(ptr, ip);
> -}
> -
>  void __kasan_kfree_large(void *ptr, unsigned long ip);
>  static inline void kasan_kfree_large(void *ptr, unsigned long ip)
>  {
> @@ -263,6 +263,7 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
>  {
>  	return false;
>  }
> +static inline void kasan_slab_free_mempool(void *ptr, unsigned long ip) {}
>  static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
>  				   gfp_t flags)
>  {
> @@ -282,7 +283,6 @@ static inline void *kasan_krealloc(const void *object, size_t new_size,
>  {
>  	return (void *)object;
>  }
> -static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
>  static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
>  
>  #endif /* CONFIG_KASAN */
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 819403548f2e..60793f8695a8 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -336,6 +336,14 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
>  	return ____kasan_slab_free(cache, object, ip, true);
>  }
>  
> +void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
> +{
> +	struct page *page;
> +
> +	page = virt_to_head_page(ptr);
> +	____kasan_slab_free(page->slab_cache, ptr, ip, false);
> +}
> +
>  static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
>  {
>  	kasan_set_track(&kasan_get_alloc_meta(cache, object)->alloc_track, flags);
> @@ -427,14 +435,6 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
>  						flags, true);
>  }
>  
> -void __kasan_poison_kfree(void *ptr, unsigned long ip)
> -{
> -	struct page *page;
> -
> -	page = virt_to_head_page(ptr);
> -	____kasan_slab_free(page->slab_cache, ptr, ip, false);
> -}
> -
>  void __kasan_kfree_large(void *ptr, unsigned long ip)
>  {
>  	if (ptr != page_address(virt_to_head_page(ptr)))
> diff --git a/mm/mempool.c b/mm/mempool.c
> index f473cdddaff0..b1f39fa75ade 100644
> --- a/mm/mempool.c
> +++ b/mm/mempool.c
> @@ -104,7 +104,7 @@ static inline void poison_element(mempool_t *pool, void *element)
>  static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
>  {
>  	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
> -		kasan_poison_kfree(element, _RET_IP_);
> +		kasan_slab_free_mempool(element, _RET_IP_);

This is already a kasan-prefixed function, so if
kasan_slab_free_mempool() is only ever called in this function, we
should just call kasan_slab_free() here directly with the 2 extra args
it requires open-coded.

>  	else if (pool->alloc == mempool_alloc_pages)
>  		kasan_free_pages(element, (unsigned long)pool->pool_data);
>  }

Thanks,
-- Marco