Re: [PATCH] powerpc: Move a dereference below a NULL test

[Christophe LEROY]

Le 26/09/2018 Ã 13:46, zhong jiang a ÃcritÂ:
> It is safe to move dereference below a NULL test.
>
> Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx>
> ---
>   arch/powerpc/kernel/cacheinfo.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
> index a8f20e5..7f19714 100644
> --- a/arch/powerpc/kernel/cacheinfo.c
> +++ b/arch/powerpc/kernel/cacheinfo.c
> @@ -401,14 +401,13 @@ static struct cache *cache_lookup_or_instantiate(struct device_node *node,
>   	struct cache *cache;
>   
>   	cache = cache_lookup_by_node(node);
> +	if (!cache)
> +		cache = cache_do_one_devnode(node, level);

But by doing this, you change the meaning of the following warning. Is 
that what you want ? In that case the text of the WARN_ONCE() should be 
changed, because the mismatch is not only on lookup now.

Christophe

>   
>   	WARN_ONCE(cache && cache->level != level,
>   		  "cache level mismatch on lookup (got %d, expected %d)\n",
>   		  cache->level, level);
>   
> -	if (!cache)
> -		cache = cache_do_one_devnode(node, level);
> -
>   	return cache;
>   }
>