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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-11-30 23:00:53 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-12-01 22:28:54 +0400 |
| commit | 84f9307c5da84a7c8513e7607dc8427d2cbd63e3 (patch) | |
| tree | f34fb0525284d97e2b10870afd8e021cc45ef44c /net/ipv4/ip_output.c | |
| parent | 898f73585bbe4bdbb471636ecdede071f7473e51 (diff) | |
| download | linux-84f9307c5da84a7c8513e7607dc8427d2cbd63e3.tar.xz | |
ipv4: use a 64bit load/store in output path
gcc compiler is smart enough to use a single load/store if we
memcpy(dptr, sptr, 8) on x86_64, regardless of
CONFIG_CC_OPTIMIZE_FOR_SIZE
In IP header, daddr immediately follows saddr, this wont change in the
future. We only need to make sure our flowi4 (saddr,daddr) fields wont
break the rule.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_output.c')
| -rw-r--r-- | net/ipv4/ip_output.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 0bc95f3977d2..0d5e5672f3d1 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -319,6 +319,20 @@ int ip_output(struct sk_buff *skb) !(IPCB(skb)->flags & IPSKB_REROUTED)); } +/* + * copy saddr and daddr, possibly using 64bit load/stores + * Equivalent to : + * iph->saddr = fl4->saddr; + * iph->daddr = fl4->daddr; + */ +static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) +{ + BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != + offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); + memcpy(&iph->saddr, &fl4->saddr, + sizeof(fl4->saddr) + sizeof(fl4->daddr)); +} + int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl) { struct sock *sk = skb->sk; @@ -381,8 +395,8 @@ packet_routed: iph->frag_off = 0; iph->ttl = ip_select_ttl(inet, &rt->dst); iph->protocol = sk->sk_protocol; - iph->saddr = fl4->saddr; - iph->daddr = fl4->daddr; + ip_copy_addrs(iph, fl4); + /* Transport layer set skb->h.foo itself. */ if (inet_opt && inet_opt->opt.optlen) { @@ -1337,8 +1351,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk, ip_select_ident(iph, &rt->dst, sk); iph->ttl = ttl; iph->protocol = sk->sk_protocol; - iph->saddr = fl4->saddr; - iph->daddr = fl4->daddr; + ip_copy_addrs(iph, fl4); if (opt) { iph->ihl += opt->optlen>>2; |