sctp: use the pmtu from the icmp packet to update transport pathmtu
authorXin Long <lucien.xin@gmail.com>
Mon, 15 Oct 2018 11:58:29 +0000 (19:58 +0800)
committerDavid S. Miller <davem@davemloft.net>
Tue, 16 Oct 2018 05:54:20 +0000 (22:54 -0700)
commitd805397c3822d57ca3884d4bea37b2291fc40992
tree26a590ccde4580779a2428d6071b87bdc967bfae
parentec20a63aa8b8ec3223fb25cdb2a49f9f9dfda88c
sctp: use the pmtu from the icmp packet to update transport pathmtu

Other than asoc pmtu sync from all transports, sctp_assoc_sync_pmtu
is also processing transport pmtu_pending by icmp packets. But it's
meaningless to use sctp_dst_mtu(t->dst) as new pmtu for a transport.

The right pmtu value should come from the icmp packet, and it would
be saved into transport->mtu_info in this patch and used later when
the pmtu sync happens in sctp_sendmsg_to_asoc or sctp_packet_config.

Besides, without this patch, as pmtu can only be updated correctly
when receiving a icmp packet and no place is holding sock lock, it
will take long time if the sock is busy with sending packets.

Note that it doesn't process transport->mtu_info in .release_cb(),
as there is no enough information for pmtu update, like for which
asoc or transport. It is not worth traversing all asocs to check
pmtu_pending. So unlike tcp, sctp does this in tx path, for which
mtu_info needs to be atomic_t.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/sctp/structs.h
net/sctp/associola.c
net/sctp/input.c
net/sctp/output.c