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Subject[PATCH net-next 3/3] net: dsa: trailer: 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_trailer.c | 31 ++-----------------------------
1 file changed, 2 insertions(+), 29 deletions(-)

diff --git a/net/dsa/tag_trailer.c b/net/dsa/tag_trailer.c
index 3a1cc24a4f0a..5b97ede56a0f 100644
--- a/net/dsa/tag_trailer.c
+++ b/net/dsa/tag_trailer.c
@@ -13,42 +13,15 @@
static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
- struct sk_buff *nskb;
- int padlen;
u8 *trailer;

- /*
- * We have to make sure that the trailer ends up as the very
- * last 4 bytes of the packet. This means that we have to pad
- * the packet to the minimum ethernet frame size, if necessary,
- * before adding the trailer.
- */
- padlen = 0;
- if (skb->len < 60)
- padlen = 60 - skb->len;
-
- nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, 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));
- consume_skb(skb);
-
- if (padlen) {
- skb_put_zero(nskb, padlen);
- }
-
- trailer = skb_put(nskb, 4);
+ trailer = skb_put(skb, 4);
trailer[0] = 0x80;
trailer[1] = 1 << dp->index;
trailer[2] = 0x10;
trailer[3] = 0x00;

- return nskb;
+ return skb;
}

static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
--
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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