On 06/07/2020 16:28, Matteo Croce wrote:
> On Mon, 6 Jul 2020 14:59:22 +0100
> Colin Ian King <colin.k...@canonical.com> wrote:
>
>> Hi,
>>
>> Static analysis with Coverity has found a potential issue in the
>> following commit:
>>
>> commit c2d6fe6163de80d7f7cf400ee351f56d6cdb7a5a
>> Author: Matteo Croce <mcr...@microsoft.com>
>> Date: Thu Jul 2 16:12:43 2020 +0200
>>
>> mvpp2: XDP TX support
>>
>>
>> In source drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c in function
>> mvpp2_check_pagepool_dma, analysis is as follows:
>>
>>
>> 4486 if (!priv->percpu_pools)
>> 4487 return err;
>> 4488
>> CID (#1 of 1): Array compared against 0 (NO_EFFECT)
>> array_null: Comparing an array to null is not useful: priv->page_pool,
>> since the test will always evaluate as true.
>>
>> Was priv->page_pool formerly declared as a pointer?
>>
>> 4489 if (!priv->page_pool)
>> 4490 return -ENOMEM;
>> 4491
>>
>>
>> page_pool is declared as:
>>
>> struct page_pool *page_pool[MVPP2_PORT_MAX_RXQ];
>>
>> ..it is an array and hence cannot be null, so the null check is
>> redundant. Later on there is a reference of priv->page_pool[0], so
>> was the check meant to be:
>>
>> if (!priv->page_pool[0])
>>
>> Colin
>
> Hi,
>
> yes, the check was meant to be 'if (!priv->page_pool[0])'.
> Maybe it's a copy/paste error from other points where 'page_pool' is a
> local variable.
>
> While at it, I've found that in case a page_pool allocation fails, I
> don't cleanup the previously allocated pools, and upon deallocation the
> pointer isn't set back to NULL.
>
> I should add something like:
>
> @@ -548,8 +548,10 @@ static int mvpp2_bm_pool_destroy(struct device
> *dev, struct mvpp2 *priv, val |= MVPP2_BM_STOP_MASK;
> mvpp2_write(priv, MVPP2_BM_POOL_CTRL_REG(bm_pool->id), val);
>
> - if (priv->percpu_pools)
> + if (priv->percpu_pools) {
> page_pool_destroy(priv->page_pool[bm_pool->id]);
> + priv->page_pool[bm_pool->id] = NULL;
> + }
>
> dma_free_coherent(dev, bm_pool->size_bytes,
> bm_pool->virt_addr,
> @@ -609,8 +611,15 @@ static int mvpp2_bm_init(struct device *dev,
> struct mvpp2 *priv) mvpp2_pools[pn].buf_num,
> mvpp2_pools[pn].pkt_size,
> dma_dir);
> - if (IS_ERR(priv->page_pool[i]))
> - return PTR_ERR(priv->page_pool[i]);
> + if (IS_ERR(priv->page_pool[i])) {
> + err = PTR_ERR(priv->page_pool[i]);
> +
> + for (i--; i >=0; i--) {
> +
> page_pool_destroy(priv->page_pool[i]);
> + priv->page_pool[i] = NULL;
> + }
> + return err;
> + }
> }
> }
>
> Looks sane to you?
>
> Regards,
>
Oh, good catch on the cleanups. Yes, that looks sane.
Colin
