ipv4: Handle PMTU in all ICMP error handlers.
With ip_rt_frag_needed() removed, we have to explicitly update PMTU information in every ICMP error handler. Create two helper functions to facilitate this. 1) ipv4_sk_update_pmtu() This updates the PMTU when we have a socket context to work with. 2) ipv4_update_pmtu() Raw version, used when no socket context is available. For this interface, we essentially just pass in explicit arguments for the flow identity information we would have extracted from the socket. And you'll notice that ipv4_sk_update_pmtu() is simply implemented in terms of ipv4_update_pmtu() Note that __ip_route_output_key() is used, rather than something like ip_route_output_flow() or ip_route_output_key(). This is because we absolutely do not want to end up with a route that does IPSEC encapsulation and the like. Instead, we only want the route that would get us to the node described by the outermost IP header. Reported-by: Steffen Klassert <email@example.com> Signed-off-by: David S. Miller <firstname.lastname@example.org>