netdev - Re: [PATCH][next] xsk: Fix null check on error return path

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Date:   Wed, 2 Sep 2020 17:12:51 +0200
From:   Björn Töpel <bjorn.topel@...el.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] xsk: Fix null check on error return path

On 2020-09-02 17:07, Gustavo A. R. Silva wrote:
> Currently, dma_map is being checked, when the right object identifier
> to be null-checked is dma_map->dma_pages, instead.
> 
> Fix this by null-checking dma_map->dma_pages.
> 
> Addresses-Coverity-ID: 1496811 ("Logically dead code")
> Fixes: 921b68692abb ("xsk: Enable sharing of dma mappings")
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Nice catch!

Acked-by: Björn Töpel <bjorn.topel@...el.com>

> ---
>   net/xdp/xsk_buff_pool.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
> index 795d7c81c0ca..5b00bc5707f2 100644
> --- a/net/xdp/xsk_buff_pool.c
> +++ b/net/xdp/xsk_buff_pool.c
> @@ -287,7 +287,7 @@ static struct xsk_dma_map *xp_create_dma_map(struct device *dev, struct net_devi
>   		return NULL;
>   
>   	dma_map->dma_pages = kvcalloc(nr_pages, sizeof(*dma_map->dma_pages), GFP_KERNEL);
> -	if (!dma_map) {
> +	if (!dma_map->dma_pages) {
>   		kfree(dma_map);
>   		return NULL;
>   	}
>