[PATCH net-next 5/6] sctp: implement prsctp RTX policy

[Xin Long]

prsctp RTX policy is a policy to abandon chunks when they are
retransmitted beyond the max count.

This patch uses sent_count to count how many times one chunk has
been sent, and prsctp_param is the max rtx count, which is from
sinfo->sinfo_timetolive in sctp_set_prsctp_policy(). So similar
to TTL policy, if RTX policy is enabled, msg->expire_at won't
work.

Then in sctp_chunk_abandoned, this patch checks if chunk->sent_count
is bigger than chunk->prsctp_param to abandon this chunk.

Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/chunk.c         | 4 ++++
 net/sctp/sm_make_chunk.c | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
index 2698d12..b3692b5 100644
--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -355,6 +355,10 @@ int sctp_chunk_abandoned(struct sctp_chunk *chunk)
                else
                        chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
                return 1;
+       } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
+                  chunk->sent_count > chunk->prsctp_param) {
+               chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
+               return 1;
        }
 
        return 0;
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 2c431ee..cfde934 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -720,6 +720,8 @@ static void sctp_set_prsctp_policy(struct sctp_chunk *chunk,
        if (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
                chunk->prsctp_param =
                        jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
+       else if (SCTP_PR_RTX_ENABLED(sinfo->sinfo_flags))
+               chunk->prsctp_param = sinfo->sinfo_timetolive;
 }
 
 /* Make a DATA chunk for the given association from the provided
-- 
2.1.0