IP: cleanup LSRR option processing

The __ip_options_echo() function expect a valid dst entry in skb->dst; as result we sometimes need to preserve the dst entry for the whole IP RX path.

The current usage of skb->dst looks more a relic from ancient past that a real functional constraint. This patchset tries to remove such usage, and than drops some hacks currently in place in the IP code to keep skb->dst around.

__ip_options_echo() uses of skb->dst for two different purposes: retrieving the netns assicated with the skb, and modify the ingress packet LSRR address list.

The first patch removes the code modifying the ingress packet, and the second one provides an explicit netns argument to __ip_options_echo(). The following patches cleanup the current code keeping arund skb->dst for __ip_options_echo's sake.

Updating the __ip_options_echo() function has been previously discussed here:

http://marc.info/?l=linux-netdev&m=150064533516348&w=2

Paolo Abeni (4):
IP: do not modify ingress packet IP option in ip_options_echo() ip/options: explicitly provide net ns to __ip_options_echo() Revert "ipv4: keep skb->dst around in presence of IP options"
udp: no need to preserve skb->dst

 include/net/ip.h       |  9 +++++----
 include/net/tcp.h      |  5 +++--
 net/ipv4/icmp.c        |  4 ++--
 net/ipv4/ip_options.c  |  9 +++------
 net/ipv4/ip_output.c   |  2 +-
 net/ipv4/ip_sockglue.c | 16 +++++-----------
 net/ipv4/syncookies.c  |  2 +-
 net/ipv4/tcp_ipv4.c    |  2 +-
 net/ipv4/udp.c         | 13 +++++--------
 9 files changed, 26 insertions(+), 36 deletions(-)

2.13.3