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Subject[PATCH net-next 2/3] net: dsa: tag_ksz: don't allocate additional memory for padding/tagging
Date
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>
---
net/dsa/tag_ksz.c | 73 ++++++-----------------------------------------
1 file changed, 9 insertions(+), 64 deletions(-)

diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 0a5aa982c60d..4820dbcedfa2 100644
--- 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 = {
--
Christian Eggers
Embedded software developer
Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918
Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477
Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler

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