net: Add MSG_WAITFORONE flag to recvmmsg
Add new flag MSG_WAITFORONE for the recvmmsg() syscall.
When this flag is specified for a blocking socket, recvmmsg()
will only block until at least 1 packet is available. The
default behavior is to block until all vlen packets are
available. This flag has no effect on non-blocking sockets
or when used in combination with MSG_DONTWAIT.
Signed-off-by: Brandon L Black <blblack@gmail.com>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 7b3aae2..354cc56 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -255,6 +255,7 @@
#define MSG_ERRQUEUE 0x2000 /* Fetch message from error queue */
#define MSG_NOSIGNAL 0x4000 /* Do not generate SIGPIPE */
#define MSG_MORE 0x8000 /* Sender will send more */
+#define MSG_WAITFORONE 0x10000 /* recvmmsg(): block until 1+ packets avail */
#define MSG_EOF MSG_FIN
diff --git a/net/socket.c b/net/socket.c
index 769c386..f55ffe9 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2135,6 +2135,10 @@
break;
++datagrams;
+ /* MSG_WAITFORONE turns on MSG_DONTWAIT after one packet */
+ if (flags & MSG_WAITFORONE)
+ flags |= MSG_DONTWAIT;
+
if (timeout) {
ktime_get_ts(timeout);
*timeout = timespec_sub(end_time, *timeout);
