[net-next,v6,2/5] net: hdlc_fr: Change the use of "dev" in fr_rx to make the code cleaner
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Message ID 20201031004918.463475-3-xie.he.0141@gmail.com
State In Next
Commit 14b20704a18062249903a7a930e27c4452bc56bc
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Series
  • net: hdlc_fr: Improve fr_rx and add support for any Ethertype
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Commit Message

Xie He Oct. 31, 2020, 12:49 a.m. UTC
The eth_type_trans function is called when we receive frames carrying
Ethernet frames. This function expects a non-NULL pointer as an argument,
and assigns it directly to skb->dev.

However, the code handling other types of frames first assigns the pointer
to "dev", and then at the end checks whether the value is NULL, and if it
is not NULL, assigns it to skb->dev.

The two flows are different. Mixing them in this function makes the code
messy. It's better that we convert the second flow to align with how
eth_type_trans does things.

So this patch changes the code to: first make sure the pointer is not
NULL, then assign it directly to skb->dev. "dev" is no longer needed until
the end where we use it to update stats.

Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
---
 drivers/net/wan/hdlc_fr.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

Patch
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diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index 4db0e01b96a9..71ee9b60d91b 100644
--- a/drivers/net/wan/hdlc_fr.c
+++ b/drivers/net/wan/hdlc_fr.c
@@ -880,7 +880,7 @@  static int fr_rx(struct sk_buff *skb)
 	u8 *data = skb->data;
 	u16 dlci;
 	struct pvc_device *pvc;
-	struct net_device *dev = NULL;
+	struct net_device *dev;
 
 	if (skb->len <= 4 || fh->ea1 || data[2] != FR_UI)
 		goto rx_error;
@@ -930,13 +930,17 @@  static int fr_rx(struct sk_buff *skb)
 	}
 
 	if (data[3] == NLPID_IP) {
+		if (!pvc->main)
+			goto rx_drop;
 		skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */
-		dev = pvc->main;
+		skb->dev = pvc->main;
 		skb->protocol = htons(ETH_P_IP);
 
 	} else if (data[3] == NLPID_IPV6) {
+		if (!pvc->main)
+			goto rx_drop;
 		skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */
-		dev = pvc->main;
+		skb->dev = pvc->main;
 		skb->protocol = htons(ETH_P_IPV6);
 
 	} else if (skb->len > 10 && data[3] == FR_PAD &&
@@ -950,13 +954,16 @@  static int fr_rx(struct sk_buff *skb)
 		case ETH_P_IPX:
 		case ETH_P_IP:	/* a long variant */
 		case ETH_P_IPV6:
-			dev = pvc->main;
+			if (!pvc->main)
+				goto rx_drop;
+			skb->dev = pvc->main;
 			skb->protocol = htons(pid);
 			break;
 
 		case 0x80C20007: /* bridged Ethernet frame */
-			if ((dev = pvc->ether) != NULL)
-				skb->protocol = eth_type_trans(skb, dev);
+			if (!pvc->ether)
+				goto rx_drop;
+			skb->protocol = eth_type_trans(skb, pvc->ether);
 			break;
 
 		default:
@@ -970,17 +977,13 @@  static int fr_rx(struct sk_buff *skb)
 		goto rx_drop;
 	}
 
-	if (dev) {
-		dev->stats.rx_packets++; /* PVC traffic */
-		dev->stats.rx_bytes += skb->len;
-		if (pvc->state.becn)
-			dev->stats.rx_compressed++;
-		skb->dev = dev;
-		netif_rx(skb);
-		return NET_RX_SUCCESS;
-	} else {
-		goto rx_drop;
-	}
+	dev = skb->dev;
+	dev->stats.rx_packets++; /* PVC traffic */
+	dev->stats.rx_bytes += skb->len;
+	if (pvc->state.becn)
+		dev->stats.rx_compressed++;
+	netif_rx(skb);
+	return NET_RX_SUCCESS;
 
 rx_error:
 	frad->stats.rx_errors++; /* Mark error */