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>

1 files changed, 7 insertions, 0 deletions

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;