linux-kernel - re: mvpp2: XDP TX support

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Message-ID: <18eb549b-d2f6-9352-582e-aec484dc95c1@canonical.com>
Date:   Mon, 6 Jul 2020 14:59:22 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Matteo Croce <mcroce@...rosoft.com>,
        Sven Auhagen <sven.auhagen@...eatech.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: re: mvpp2: XDP TX support

Hi,

Static analysis with Coverity has found a potential issue in the
following commit:

commit c2d6fe6163de80d7f7cf400ee351f56d6cdb7a5a
Author: Matteo Croce <mcroce@...rosoft.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