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,
--
per aspera ad upstream
