linux/net/ipv4/ip_input.c, branch v3.8

net: TCP early demux cleanup

2012-07-30T21:53:21Z

early_demux() handlers should be called in RCU context, and as we use skb_dst_set_noref(skb, dst), caller must not exit from RCU context before dst use (skb_dst(skb)) or release (skb_drop(dst)) Therefore, rcu_read_lock()/rcu_read_unlock() pairs around ->early_demux() are confusing and not needed : Protocol handlers are already in an RCU read lock section. (__netif_receive_skb() does the rcu_read_lock() ) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: Early TCP socket demux

2012-07-26T22:50:39Z

This is the IPv6 missing bits for infrastructure added in commit 41063e9dd1195 (ipv4: Early TCP socket demux.) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv4: Fix input route performance regression.

2012-07-26T22:50:39Z

With the routing cache removal we lost the "noref" code paths on input, and this can kill some routing workloads. Reinstate the noref path when we hit a cached route in the FIB nexthops. With help from Eric Dumazet. Reported-by: Alexander Duyck Signed-off-by: David S. Miller Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: early_demux fixes

2012-07-24T20:54:15Z

1) Remove a non needed pskb_may_pull() in tcp_v4_early_demux() and fix a potential bug if skb->head was reallocated (iph & th pointers were not reloaded) TCP stack will pull/check headers anyway. 2) must reload iph in ip_rcv_finish() after early_demux() call since skb->head might have changed. 3) skb->dev->ifindex can be now replaced by skb->skb_iif Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv4: Kill ip_route_input_noref().

2012-07-20T20:30:59Z

The "noref" argument to ip_route_input_common() is now always ignored because we do not cache routes, and in that case we must always grab a reference to the resulting 'dst'. Signed-off-by: David S. Miller

ipv4: Kill early demux method return value.

2012-06-28T05:01:22Z

It's completely unnecessary. Signed-off-by: David S. Miller

Revert "ipv4: tcp: dont cache unconfirmed intput dst"

2012-06-28T00:05:06Z

This reverts commit c074da2810c118b3812f32d6754bd9ead2f169e7. This change has several unwanted side effects: 1) Sockets will cache the DST_NOCACHE route in sk->sk_rx_dst and we'll thus never create a real cached route. 2) All TCP traffic will use DST_NOCACHE and never use the routing cache at all. Signed-off-by: David S. Miller

ipv4: tcp: dont cache unconfirmed intput dst

2012-06-27T22:34:24Z

DDOS synflood attacks hit badly IP route cache. On typical machines, this cache is allowed to hold up to 8 Millions dst entries, 256 bytes for each, for a total of 2GB of memory. rt_garbage_collect() triggers and tries to cleanup things. Eventually route cache is disabled but machine is under fire and might OOM and crash. This patch exploits the new TCP early demux, to set a nocache boolean in case incoming TCP frame is for a not yet ESTABLISHED or TIMEWAIT socket. This 'nocache' boolean is then used in case dst entry is not found in route cache, to create an unhashed dst entry (DST_NOCACHE) SYN-cookie-ACK sent use a similar mechanism (ipv4: tcp: dont cache output dst for syncookies), so after this patch, a machine is able to absorb a DDOS synflood attack without polluting its IP route cache. Signed-off-by: Eric Dumazet Cc: Hans Schillstrom Signed-off-by: David S. Miller

ipv4: Cache ip_error() routes even when not forwarding.

2012-06-26T23:27:09Z

And account for the fact that, when we are not forwarding, we should bump statistic counters rather than emit an ICMP response. RP-filter rejected lookups are still not cached. Since -EHOSTUNREACH and -ENETUNREACH can now no longer be seen in ip_rcv_finish(), remove those checks. Signed-off-by: David S. Miller

ipv4: Add sysctl knob to control early socket demux

2012-06-23T00:11:13Z

This change is meant to add a control for disabling early socket demux. The main motivation behind this patch is to provide an option to disable the feature as it adds an additional cost to routing that reduces overall throughput by up to 5%. For example one of my systems went from 12.1Mpps to 11.6 after the early socket demux was added. It looks like the reason for the regression is that we are now having to perform two lookups, first the one for an established socket, and then the one for the routing table. By adding this patch and toggling the value for ip_early_demux to 0 I am able to get back to the 12.1Mpps I was previously seeing. [ Move local variables in ip_rcv_finish() down into the basic block in which they are actually used. -DaveM ] Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller