linux-kernel - [PATCH net-next v2] net: hdlc_x25: Remove unnecessary skb_reset_network

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Message-Id: <20201209014013.4996-1-xie.he.0141@gmail.com>
Date:   Tue,  8 Dec 2020 17:40:13 -0800
From:   Xie He <xie.he.0141@...il.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-x25@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Martin Schiller <ms@....tdt.de>
Cc:     Xie He <xie.he.0141@...il.com>
Subject: [PATCH net-next v2] net: hdlc_x25: Remove unnecessary skb_reset_network_header calls

1. In x25_xmit, skb_reset_network_header is not necessary before we call
lapb_data_request. The lapb module doesn't need skb->network_header.
So there is no need to set skb->network_header before calling
lapb_data_request.

2. In x25_data_indication (called by the lapb module after some data
have been received), skb_reset_network_header is not necessary before we
call netif_rx. After we call netif_rx, the code in net/core/dev.c will
call skb_reset_network_header before handing the skb to upper layers
(in __netif_receive_skb_core, called by __netif_receive_skb_one_core,
called by __netif_receive_skb, called by process_backlog). So we don't
need to call skb_reset_network_header by ourselves.

Cc: Martin Schiller <ms@....tdt.de>
Signed-off-by: Xie He <xie.he.0141@...il.com>
---
 drivers/net/wan/hdlc_x25.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c
index f52b9fed0593..bb164805804e 100644
--- a/drivers/net/wan/hdlc_x25.c
+++ b/drivers/net/wan/hdlc_x25.c
@@ -77,7 +77,6 @@ static int x25_data_indication(struct net_device *dev, struct sk_buff *skb)
 	}

 	skb_push(skb, 1);
-	skb_reset_network_header(skb);

 	ptr  = skb->data;
 	*ptr = X25_IFACE_DATA;
@@ -118,7 +117,6 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
 	switch (skb->data[0]) {
 	case X25_IFACE_DATA:	/* Data to be transmitted */
 		skb_pull(skb, 1);
-		skb_reset_network_header(skb);
 		if ((result = lapb_data_request(dev, skb)) != LAPB_OK)
 			dev_kfree_skb(skb);
 		return NETDEV_TX_OK;
-- 
2.27.0