From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brandon L Black Subject: [PATCH] Add MSG_WAITFORONE flag to recvmmsg Date: Fri, 26 Mar 2010 17:35:30 -0500 Message-ID: <20100326223530.GA11817@xpc.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , Arnaldo Carvalho de Melo , Ulrich Drepper , linux-kernel@vger.kernel.org To: netdev@vger.kernel.org Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Brandon L Black 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 --- 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 @@ struct ucred { #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..33304d1 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2133,7 +2133,10 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, if (err) break; - ++datagrams; + + /* MSG_WAITFORONE turns on MSG_DONTWAIT after one packet */ + if (!datagrams++ && (flags & MSG_WAITFORONE)) + flags |= MSG_DONTWAIT; if (timeout) { ktime_get_ts(timeout);