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| author | David S. Miller <davem@davemloft.net> | 2005-09-27 16:03:05 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2005-09-27 16:03:05 -0700 |
| commit | ba645c16026ed733a51f904df34756f61bc155fc (patch) | |
| tree | 504d51adf47bb9fa3cd548e5594f15a60faeba6c | |
| parent | 2fab35d78f32fc107e1af4b1ec23f557fa20d911 (diff) | |
| download | linux-ba645c16026ed733a51f904df34756f61bc155fc.tar.gz linux-ba645c16026ed733a51f904df34756f61bc155fc.tar.bz2 linux-ba645c16026ed733a51f904df34756f61bc155fc.zip | |
[NET]: Slightly optimize ethernet address comparison.
We know the thing is at least 2-byte aligned, so take
advantage of that instead of invoking memcmp() which
results in truly horrifically inefficient code because
it can't assume anything about alignment.
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ethernet/eth.c | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index 87a052a9a84f..8b299cc82060 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -146,6 +146,19 @@ int eth_rebuild_header(struct sk_buff *skb) return 0; } +static inline unsigned int compare_eth_addr(const unsigned char *__a, const unsigned char *__b) +{ + const unsigned short *dest = (unsigned short *) __a; + const unsigned short *devaddr = (unsigned short *) __b; + unsigned int res; + + BUILD_BUG_ON(ETH_ALEN != 6); + res = ((dest[0] ^ devaddr[0]) | + (dest[1] ^ devaddr[1]) | + (dest[2] ^ devaddr[2])) != 0; + + return res; +} /* * Determine the packet's protocol ID. The rule here is that we @@ -158,16 +171,15 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) struct ethhdr *eth; unsigned char *rawp; - skb->mac.raw=skb->data; + skb->mac.raw = skb->data; skb_pull(skb,ETH_HLEN); eth = eth_hdr(skb); - if(*eth->h_dest&1) - { - if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0) - skb->pkt_type=PACKET_BROADCAST; + if (*eth->h_dest&1) { + if (!compare_eth_addr(eth->h_dest, dev->broadcast)) + skb->pkt_type = PACKET_BROADCAST; else - skb->pkt_type=PACKET_MULTICAST; + skb->pkt_type = PACKET_MULTICAST; } /* @@ -178,10 +190,9 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) * seems to set IFF_PROMISC. */ - else if(1 /*dev->flags&IFF_PROMISC*/) - { - if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN)) - skb->pkt_type=PACKET_OTHERHOST; + else if(1 /*dev->flags&IFF_PROMISC*/) { + if (unlikely(!compare_eth_addr(eth->h_dest, dev->dev_addr))) + skb->pkt_type = PACKET_OTHERHOST; } if (ntohs(eth->h_proto) >= 1536) |