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From: Xie He <xie.he.0141@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Krzysztof Halasa <khc@pm.waw.pl>
Cc: Xie He <xie.he.0141@gmail.com>
Subject: [PATCH net-next v2 2/4] net: hdlc_fr: Change the use of "dev" in fr_rx to make the code cleaner
Date: Wed, 28 Oct 2020 06:18:05 -0700	[thread overview]
Message-ID: <20201028131807.3371-3-xie.he.0141@gmail.com> (raw)
In-Reply-To: <20201028131807.3371-1-xie.he.0141@gmail.com>

The eth_type_trans function is called when we receive frames carrying
Ethernet frames. This function expects a non-NULL pointer as a argument,
and assigns it directly to skb->dev.

However, the code handling other types of frames first assigns a 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: 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(-)

diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index c774eff44534..ac65f5c435ef 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 */
-- 
2.25.1


  parent reply	other threads:[~2020-10-28 22:35 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-28 13:18 [PATCH net-next v2 0/4] net: hdlc_fr: Add support for any Ethertype Xie He
2020-10-28 13:18 ` [PATCH net-next v2 1/4] net: hdlc_fr: Simpify fr_rx by using "goto rx_drop" to drop frames Xie He
2020-10-28 13:18 ` Xie He [this message]
2020-10-28 13:18 ` [PATCH net-next v2 3/4] net: hdlc_fr: Improve the initial check when we receive an skb Xie He
2020-10-28 13:18 ` [PATCH net-next v2 4/4] net: hdlc_fr: Add support for any Ethertype Xie He
2020-10-29 17:23   ` Willem de Bruijn
2020-10-29 23:53     ` Xie He
2020-10-30  0:49       ` Xie He
2020-10-30  0:53         ` Willem de Bruijn
2020-10-30  0:50       ` Willem de Bruijn

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