netdev - [PATCH net-next 1/5] net: dsa: tag_rtl4_a: __skb_put

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Message-Id: <20220511151431.780120-2-vladimir.oltean@nxp.com>
Date:   Wed, 11 May 2022 18:14:27 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next 1/5] net: dsa: tag_rtl4_a: __skb_put_padto() can never fail

One of the purposes of the central dsa_realloc_skb() is to ensure that
the skb has a geometry which does not need to be adjusted by tagging
protocol drivers for most cases. This includes making sure that the skb
is not cloned (otherwise pskb_expand_head() is called).

So there is no reason why __skb_put_padto() is going to return an error,
otherwise it would have returned the error in dsa_realloc_skb().

Use the simple eth_skb_pad() which passes "true" to "free_on_error"
(which does not matter) and save a conditional in the TX data path.
With this, also remove the uninformative comment.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/tag_rtl4_a.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/dsa/tag_rtl4_a.c b/net/dsa/tag_rtl4_a.c
index 6d928ee3ef7a..e71d011ce4cc 100644
--- a/net/dsa/tag_rtl4_a.c
+++ b/net/dsa/tag_rtl4_a.c
@@ -39,9 +39,7 @@ static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
 	u8 *tag;
 	u16 out;

-	/* Pad out to at least 60 bytes */
-	if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false)))
-		return NULL;
+	eth_skb_pad(skb);

 	netdev_dbg(dev, "add realtek tag to package to port %d\n",
 		   dp->index);
-- 
2.25.1