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[net-next,2/4] net: dsa: tag_brcm: Prepare for supporting prepended tag

Message ID 20171110232255.2462-3-f.fainelli@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show
Series net: dsa: b53: Support prepended Broadcom tags | expand

Commit Message

Florian Fainelli Nov. 10, 2017, 11:22 p.m. UTC 
In preparation for supporting the same Broadcom tag format, but instead
of inserted between the MAC SA and EtherType, prepended to the Ethernet
frame, restructure the code a little bit to make that possible and take
an offset parameter.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 net/dsa/tag_brcm.c | 45 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 11 deletions(-)

Comments

Andrew Lunn Nov. 11, 2017, 3:50 p.m. UTC | #1 
> +static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
> +				       struct net_device *dev,
> +				       struct packet_type *pt,
> +				       unsigned int offset)
>  {
>  	int source_port;
>  	u8 *brcm_tag;
> @@ -103,8 +114,7 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
>  	if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
>  		return NULL;
>  
> -	/* skb->data points to the EtherType, the tag is right before it */
> -	brcm_tag = skb->data - 2;
> +	brcm_tag = skb->data - offset;

A minor nit.

The first part of the comment is still true. And having it gives you
an anchor point to understanding where are we going from when we go
backwards in the packet. Yes, the comment appears later, but at that
point we are not dealing with skb->data.

Otherwise:

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew
diff mbox series

Patch

diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index 9e082bae3cb0..771409a1e65c 100644
--- a/net/dsa/tag_brcm.c
+++ b/net/dsa/tag_brcm.c
@@ -59,7 +59,9 @@ 
 #define BRCM_EG_TC_MASK		0x7
 #define BRCM_EG_PID_MASK	0x1f
 
-static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
+static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
+					struct net_device *dev,
+					unsigned int offset)
 {
 	struct dsa_port *dp = dsa_slave_to_port(dev);
 	u16 queue = skb_get_queue_mapping(skb);
@@ -70,10 +72,10 @@  static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev
 
 	skb_push(skb, BRCM_TAG_LEN);
 
-	memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
+	if (offset)
+		memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
 
-	/* Build the tag after the MAC Source Address */
-	brcm_tag = skb->data + 2 * ETH_ALEN;
+	brcm_tag = skb->data + offset;
 
 	/* Set the ingress opcode, traffic class, tag enforcment is
 	 * deprecated
@@ -94,8 +96,17 @@  static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev
 	return skb;
 }
 
-static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
-				    struct packet_type *pt)
+static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	/* Build the tag after the MAC Source Address */
+	return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
+}
+
+static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
+				       struct net_device *dev,
+				       struct packet_type *pt,
+				       unsigned int offset)
 {
 	int source_port;
 	u8 *brcm_tag;
@@ -103,8 +114,7 @@  static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 	if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 		return NULL;
 
-	/* skb->data points to the EtherType, the tag is right before it */
-	brcm_tag = skb->data - 2;
+	brcm_tag = skb->data - offset;
 
 	/* The opcode should never be different than 0b000 */
 	if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
@@ -126,12 +136,25 @@  static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 	/* Remove Broadcom tag and update checksum */
 	skb_pull_rcsum(skb, BRCM_TAG_LEN);
 
+	return skb;
+}
+
+static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
+				    struct packet_type *pt)
+{
+	struct sk_buff *nskb;
+
+	/* skb->data points to the EtherType, the tag is right before it */
+	nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
+	if (!nskb)
+		return nskb;
+
 	/* Move the Ethernet DA and SA */
-	memmove(skb->data - ETH_HLEN,
-		skb->data - ETH_HLEN - BRCM_TAG_LEN,
+	memmove(nskb->data - ETH_HLEN,
+		nskb->data - ETH_HLEN - BRCM_TAG_LEN,
 		2 * ETH_ALEN);
 
-	return skb;
+	return nskb;
 }
 
 const struct dsa_device_ops brcm_netdev_ops = {