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authorEric Dumazet <edumazet@google.com>2014-06-02 05:26:03 -0700
committerDavid S. Miller <davem@davemloft.net>2014-06-02 11:00:41 -0700
commit73f156a6e8c1074ac6327e0abd1169e95eb66463 (patch)
tree2c8b222f21784e738c397ba95dee70a8f256ea64 /net/ipv6/output_core.c
parente067ee336a9d3f038ffa9699c59f2abec3376bf7 (diff)
inetpeer: get rid of ip_id_count
Ideally, we would need to generate IP ID using a per destination IP generator. linux kernels used inet_peer cache for this purpose, but this had a huge cost on servers disabling MTU discovery. 1) each inet_peer struct consumes 192 bytes 2) inetpeer cache uses a binary tree of inet_peer structs, with a nominal size of ~66000 elements under load. 3) lookups in this tree are hitting a lot of cache lines, as tree depth is about 20. 4) If server deals with many tcp flows, we have a high probability of not finding the inet_peer, allocating a fresh one, inserting it in the tree with same initial ip_id_count, (cf secure_ip_id()) 5) We garbage collect inet_peer aggressively. IP ID generation do not have to be 'perfect' Goal is trying to avoid duplicates in a short period of time, so that reassembly units have a chance to complete reassembly of fragments belonging to one message before receiving other fragments with a recycled ID. We simply use an array of generators, and a Jenkin hash using the dst IP as a key. ipv6_select_ident() is put back into net/ipv6/ip6_output.c where it belongs (it is only used from this file) secure_ip_id() and secure_ipv6_id() no longer are needed. Rename ip_select_ident_more() to ip_select_ident_segs() to avoid unnecessary decrement/increment of the number of segments. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/output_core.c')
-rw-r--r--net/ipv6/output_core.c30
1 files changed, 0 insertions, 30 deletions
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 6313abd53c9d..6179ac186ab9 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -8,36 +8,6 @@
#include <net/addrconf.h>
#include <net/secure_seq.h>
-void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
-{
- static atomic_t ipv6_fragmentation_id;
- struct in6_addr addr;
- int old, new;
-
-#if IS_ENABLED(CONFIG_IPV6)
- struct inet_peer *peer;
- struct net *net;
-
- net = dev_net(rt->dst.dev);
- peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
- if (peer) {
- fhdr->identification = htonl(inet_getid(peer, 0));
- inet_putpeer(peer);
- return;
- }
-#endif
- do {
- old = atomic_read(&ipv6_fragmentation_id);
- new = old + 1;
- if (!new)
- new = 1;
- } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old);
-
- addr = rt->rt6i_dst.addr;
- addr.s6_addr32[0] ^= (__force __be32)new;
- fhdr->identification = htonl(secure_ipv6_id(addr.s6_addr32));
-}
-EXPORT_SYMBOL(ipv6_select_ident);
int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
{

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