sctp: add support for busy polling to sctp protocol

The busy polling socket option adds support for sockets to busy wait on data
arriving on the napi queue from which they have most recently received a frame.
Currently only tcp and udp support this feature, but theres no reason sctp can't
do so as well.  Add it in so appliations can take advantage of it

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Daniel Borkmann <dborkman@redhat.com>
CC: netdev@vger.kernel.org
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fee06b99a4da..e37b2cbbf177 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -71,6 +71,7 @@
 #include <net/route.h>
 #include <net/ipv6.h>
 #include <net/inet_common.h>
+#include <net/busy_poll.h>
 
 #include <linux/socket.h> /* for sa_family_t */
 #include <linux/export.h>
@@ -6557,6 +6558,10 @@ static struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags,
                 if (sk->sk_shutdown & RCV_SHUTDOWN)
                         break;
 
+                if (sk_can_busy_loop(sk) &&
+                    sk_busy_loop(sk, noblock))
+                        continue;
+
                 /* User doesn't want to wait.  */
                 error = -EAGAIN;
                 if (!timeo)