net: Add sendmmsg socket system call

This patch adds a multiple message send syscall and is the send
version of the existing recvmmsg syscall. This is heavily
based on the patch by Arnaldo that added recvmmsg.

I wrote a microbenchmark to test the performance gains of using
this new syscall:

http://ozlabs.org/~anton/junkcode/sendmmsg_test.c

The test was run on a ppc64 box with a 10 Gbit network card. The
benchmark can send both UDP and RAW ethernet packets.

64B UDP

batch   pkts/sec
1       804570
2       872800 (+ 8 %)
4       916556 (+14 %)
8       939712 (+17 %)
16      952688 (+18 %)
32      956448 (+19 %)
64      964800 (+20 %)

64B raw socket

batch   pkts/sec
1       1201449
2       1350028 (+12 %)
4       1461416 (+22 %)
8       1513080 (+26 %)
16      1541216 (+28 %)
32      1553440 (+29 %)
64      1557888 (+30 %)

We see a 20% improvement in throughput on UDP send and 30%
on raw socket send.

[ Add sparc syscall entries. -DaveM ]

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 3 deletions

diff --git a/net/compat.c b/net/compat.c
index 3649d58..c578d93 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -722,11 +722,11 @@ EXPORT_SYMBOL(compat_mc_getsockopt);
 
 /* Argument list sizes for compat_sys_socketcall */
 #define AL(x) ((x) * sizeof(u32))
-static unsigned char nas[20] = {
+static unsigned char nas[21] = {
 	AL(0), AL(3), AL(3), AL(3), AL(2), AL(3),
 	AL(3), AL(3), AL(4), AL(4), AL(4), AL(6),
 	AL(6), AL(2), AL(5), AL(5), AL(3), AL(3),
-	AL(4), AL(5)
+	AL(4), AL(5), AL(4)
 };
 #undef AL
 
@@ -735,6 +735,13 @@ asmlinkage long compat_sys_sendmsg(int fd, struct compat_msghdr __user *msg, uns
 	return sys_sendmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
 }
 
+asmlinkage long compat_sys_sendmmsg(int fd, struct compat_mmsghdr __user *mmsg,
+				    unsigned vlen, unsigned int flags)
+{
+	return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
+			      flags | MSG_CMSG_COMPAT);
+}
+
 asmlinkage long compat_sys_recvmsg(int fd, struct compat_msghdr __user *msg, unsigned int flags)
 {
 	return sys_recvmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
@@ -780,7 +787,7 @@ asmlinkage long compat_sys_socketcall(int call, u32 __user *args)
 	u32 a[6];
 	u32 a0, a1;
 
-	if (call < SYS_SOCKET || call > SYS_RECVMMSG)
+	if (call < SYS_SOCKET || call > SYS_SENDMMSG)
 		return -EINVAL;
 	if (copy_from_user(a, args, nas[call]))
 		return -EFAULT;
@@ -839,6 +846,9 @@ asmlinkage long compat_sys_socketcall(int call, u32 __user *args)
 	case SYS_SENDMSG:
 		ret = compat_sys_sendmsg(a0, compat_ptr(a1), a[2]);
 		break;
+	case SYS_SENDMMSG:
+		ret = compat_sys_sendmmsg(a0, compat_ptr(a1), a[2], a[3]);
+		break;
 	case SYS_RECVMSG:
 		ret = compat_sys_recvmsg(a0, compat_ptr(a1), a[2]);
 		break;