sctp: implement prsctp PRIO policy
prsctp PRIO policy is a policy to abandon lower priority chunks when
asoc doesn't have enough snd buffer, so that the current chunk with
higher priority can be queued successfully.
Similar to TTL/RTX policy, we will set the priority of the chunk to
prsctp_param with sinfo->sinfo_timetolive in sctp_set_prsctp_policy().
So if PRIO policy is enabled, msg->expire_at won't work.
asoc->sent_cnt_removable will record how many chunks can be checked to
remove. If priority policy is enabled, when the chunk is queued into
the out_queue, we will increase sent_cnt_removable. When the chunk is
moved to abandon_queue or dequeue and free, we will decrease
sent_cnt_removable.
In sctp_sendmsg, we will check if there is enough snd buffer for current
msg and if sent_cnt_removable is not 0. Then try to abandon chunks in
sctp_prune_prsctp when sendmsg from the retransmit/transmited queue, and
free chunks from out_queue in right order until the abandon+free size >
msg_len - sctp_wfree. For the abandon size, we have to wait until it
sends FORWARD TSN, receives the sack and the chunks are really freed.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 0861429..71c7dc5 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1914,6 +1914,9 @@
goto out_free;
}
+ if (sctp_wspace(asoc) < msg_len)
+ sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc));
+
timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
if (!sctp_wspace(asoc)) {
err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
