net: dsa: tag_ksz: don't allocate additional memory for padding/tagging

The caller (dsa_slave_xmit) guarantees that the frame length is at least
ETH_ZLEN and that enough memory for tail tagging is available.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 0a5aa98..4820dbc 100644 (file)
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -14,46 +14,6 @@
 #define KSZ_EGRESS_TAG_LEN             1
 #define KSZ_INGRESS_TAG_LEN            1
 
-static struct sk_buff *ksz_common_xmit(struct sk_buff *skb,
-                                      struct net_device *dev, int len)
-{
-       struct sk_buff *nskb;
-       int padlen;
-
-       padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
-
-       if (skb_tailroom(skb) >= padlen + len) {
-               /* Let dsa_slave_xmit() free skb */
-               if (__skb_put_padto(skb, skb->len + padlen, false))
-                       return NULL;
-
-               nskb = skb;
-       } else {
-               nskb = alloc_skb(NET_IP_ALIGN + skb->len +
-                                padlen + len, GFP_ATOMIC);
-               if (!nskb)
-                       return NULL;
-               skb_reserve(nskb, NET_IP_ALIGN);
-
-               skb_reset_mac_header(nskb);
-               skb_set_network_header(nskb,
-                                      skb_network_header(skb) - skb->head);
-               skb_set_transport_header(nskb,
-                                        skb_transport_header(skb) - skb->head);
-               skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
-
-               /* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
-                * skb
-                */
-               if (skb_put_padto(nskb, nskb->len + padlen))
-                       return NULL;
-
-               consume_skb(skb);
-       }
-
-       return nskb;
-}
-
 static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
                                      struct net_device *dev,
                                      unsigned int port, unsigned int len)
@@ -90,23 +50,18 @@ static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
 static struct sk_buff *ksz8795_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct dsa_port *dp = dsa_slave_to_port(dev);
-       struct sk_buff *nskb;
        u8 *tag;
        u8 *addr;
 
-       nskb = ksz_common_xmit(skb, dev, KSZ_INGRESS_TAG_LEN);
-       if (!nskb)
-               return NULL;
-
        /* Tag encoding */
-       tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
-       addr = skb_mac_header(nskb);
+       tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
+       addr = skb_mac_header(skb);
 
        *tag = 1 << dp->index;
        if (is_link_local_ether_addr(addr))
                *tag |= KSZ8795_TAIL_TAG_OVERRIDE;
 
-       return nskb;
+       return skb;
 }
 
 static struct sk_buff *ksz8795_rcv(struct sk_buff *skb, struct net_device *dev,
@@ -156,18 +111,13 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
 {
        struct dsa_port *dp = dsa_slave_to_port(dev);
-       struct sk_buff *nskb;
        __be16 *tag;
        u8 *addr;
        u16 val;
 
-       nskb = ksz_common_xmit(skb, dev, KSZ9477_INGRESS_TAG_LEN);
-       if (!nskb)
-               return NULL;
-
        /* Tag encoding */
-       tag = skb_put(nskb, KSZ9477_INGRESS_TAG_LEN);
-       addr = skb_mac_header(nskb);
+       tag = skb_put(skb, KSZ9477_INGRESS_TAG_LEN);
+       addr = skb_mac_header(skb);
 
        val = BIT(dp->index);
 
@@ -176,7 +126,7 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
 
        *tag = cpu_to_be16(val);
 
-       return nskb;
+       return skb;
 }
 
 static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev,
@@ -213,24 +163,19 @@ static struct sk_buff *ksz9893_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
 {
        struct dsa_port *dp = dsa_slave_to_port(dev);
-       struct sk_buff *nskb;
        u8 *addr;
        u8 *tag;
 
-       nskb = ksz_common_xmit(skb, dev, KSZ_INGRESS_TAG_LEN);
-       if (!nskb)
-               return NULL;
-
        /* Tag encoding */
-       tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
-       addr = skb_mac_header(nskb);
+       tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
+       addr = skb_mac_header(skb);
 
        *tag = BIT(dp->index);
 
        if (is_link_local_ether_addr(addr))
                *tag |= KSZ9893_TAIL_TAG_OVERRIDE;
 
-       return nskb;
+       return skb;
 }
 
 static const struct dsa_device_ops ksz9893_netdev_ops = {