Re: [Tarantool-patches] [PATCH 1/3] b-tree: return NULL on matras_alloc fail

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Hi! Thanks for the patch!

On 13/12/2019 08:05, Ilya Kosarev wrote:
> In bps_tree_create_leaf we use matras_alloc in case
> bps_tree_garbage_pop didn't work out. However it also might not
> succeed. Then we need to return NULL instead of dereferencing NULL
> pointer.
> 
> Prerequisites: #3807
> ---
>  src/lib/salad/bps_tree.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/lib/salad/bps_tree.h b/src/lib/salad/bps_tree.h
> index d28b53f53c8..51f5c8b5556 100644
> --- a/src/lib/salad/bps_tree.h
> +++ b/src/lib/salad/bps_tree.h
> @@ -2149,6 +2149,8 @@ bps_tree_create_leaf(struct bps_tree *tree, bps_tree_block_id_t *id)
>  			       bps_tree_garbage_pop(tree, id);
>  	if (!res)
>  		res = (struct bps_leaf *)matras_alloc(&tree->matras, id);
> +	if (!res)
> +		return NULL;

In case res was not NULL (what is 99.(9)% of all cases), you
will double check it. Please, move the second check into first
'if's body after matras_alloc.