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| author |   Eric Dumazet <eric.dumazet@gmail.com> | 2011-07-28 04:32:25 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2011-08-01 00:12:00 -0700 |
| commit | 89b0212697e92bc59a021a2338cd8c09f919325c (patch) | |
| tree | 633279786602d3677ea5c4959528aa00219afed2 /net | |
| parent | ipv6: avoid a dst_entry refcount change in ipv6_destopt_rcv() (diff) | |
| download | linux-dev-89b0212697e92bc59a021a2338cd8c09f919325c.tar.xz linux-dev-89b0212697e92bc59a021a2338cd8c09f919325c.zip | |
ip6tnl: avoid touching dst refcount in ip6_tnl_xmit2()
Even using percpu stats, we still hit tunnel dst_entry refcount in
ip6_tnl_xmit2()
Since we are in RCU locked section, we can use skb_dst_set_noref() and
avoid these atomic operations, leaving dst shared on cpus.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
| -rw-r--r-- | net/ipv6/ip6_tunnel.c | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 0bc98886c383..6fb1fb3624bf 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -889,7 +889,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb, struct net_device_stats *stats = &t->dev->stats; struct ipv6hdr *ipv6h = ipv6_hdr(skb); struct ipv6_tel_txoption opt; - struct dst_entry *dst; + struct dst_entry *dst, *ndst = NULL; struct net_device *tdev; int mtu; unsigned int max_headroom = sizeof(struct ipv6hdr); @@ -897,19 +897,19 @@ static int ip6_tnl_xmit2(struct sk_buff *skb, int err = -1; int pkt_len; - if ((dst = ip6_tnl_dst_check(t)) != NULL) - dst_hold(dst); - else { - dst = ip6_route_output(net, NULL, fl6); + dst = ip6_tnl_dst_check(t); + if (!dst) { + ndst = ip6_route_output(net, NULL, fl6); - if (dst->error) + if (ndst->error) goto tx_err_link_failure; - dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), NULL, 0); - if (IS_ERR(dst)) { - err = PTR_ERR(dst); - dst = NULL; + ndst = xfrm_lookup(net, ndst, flowi6_to_flowi(fl6), NULL, 0); + if (IS_ERR(ndst)) { + err = PTR_ERR(ndst); + ndst = NULL; goto tx_err_link_failure; } + dst = ndst; } tdev = dst->dev; @@ -955,7 +955,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb, skb = new_skb; } skb_dst_drop(skb); - skb_dst_set(skb, dst_clone(dst)); + skb_dst_set_noref(skb, dst); skb->transport_header = skb->network_header; @@ -987,13 +987,14 @@ static int ip6_tnl_xmit2(struct sk_buff *skb, stats->tx_errors++; stats->tx_aborted_errors++; } - ip6_tnl_dst_store(t, dst); + if (ndst) + ip6_tnl_dst_store(t, ndst); return 0; tx_err_link_failure: stats->tx_carrier_errors++; dst_link_failure(skb); tx_err_dst_release: - dst_release(dst); + dst_release(ndst); return err; } |