From fb586f25300f4587c7ebd097a604bf269b25bfa7 Mon Sep 17 00:00:00 2001
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Fri, 8 Apr 2016 16:41:28 -0300
Subject: sctp: delay calls to sk_data_ready() as much as possible

Currently processing of multiple chunks in a single SCTP packet leads to
multiple calls to sk_data_ready, causing multiple wake up signals which
are costy and doesn't make it wake up any faster.

With this patch it will note that the wake up is pending and will do it
before leaving the state machine interpreter, latest place possible to
do it realiably and cleanly.

Note that sk_data_ready events are not dependent on asocs, unlike waking
up writers.

v2: series re-checked
v3: use local vars to cleanup the code, suggested by Jakub Sitnicki
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 1a6a626..21cb111 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -217,7 +217,8 @@ struct sctp_sock {
 		v4mapped:1,
 		frag_interleave:1,
 		recvrcvinfo:1,
-		recvnxtinfo:1;
+		recvnxtinfo:1,
+		pending_data_ready:1;
 
 	atomic_t pd_mode;
 	/* Receive to here while partial delivery is in effect. */
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 7fe56d0..d06317d 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1222,6 +1222,8 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 				sctp_cmd_seq_t *commands,
 				gfp_t gfp)
 {
+	struct sock *sk = ep->base.sk;
+	struct sctp_sock *sp = sctp_sk(sk);
 	int error = 0;
 	int force;
 	sctp_cmd_t *cmd;
@@ -1742,6 +1744,11 @@ out:
 			error = sctp_outq_uncork(&asoc->outqueue, gfp);
 	} else if (local_cork)
 		error = sctp_outq_uncork(&asoc->outqueue, gfp);
+
+	if (sp->pending_data_ready) {
+		sk->sk_data_ready(sk);
+		sp->pending_data_ready = 0;
+	}
 	return error;
 nomem:
 	error = -ENOMEM;
diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c
index ce469d6..72e5b3e 100644
--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -264,7 +264,7 @@ int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 		sctp_ulpq_clear_pd(ulpq);
 
 	if (queue == &sk->sk_receive_queue)
-		sk->sk_data_ready(sk);
+		sctp_sk(sk)->pending_data_ready = 1;
 	return 1;
 
 out_free:
@@ -1140,5 +1140,5 @@ void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
 
 	/* If there is data waiting, send it up the socket now. */
 	if (sctp_ulpq_clear_pd(ulpq) || ev)
-		sk->sk_data_ready(sk);
+		sctp_sk(sk)->pending_data_ready = 1;
 }
-- 
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