uml: add VDE networking support

Added vde network backend in uml to introduce native Virtual Distributed
Ethernet support (using libvdeplug).

Signed-off-by: Luca Bigliardi <shammash@artha.org>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/vde_user.c

@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2007 Luca Bigliardi (shammash@artha.org).
+ * Licensed under the GPL.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <libvdeplug.h>
+#include "net_user.h"
+#include "kern_util.h"
+#include "kern_constants.h"
+#include "user.h"
+#include "os.h"
+#include "um_malloc.h"
+#include "vde.h"
+
+#define MAX_PACKET (ETH_MAX_PACKET + ETH_HEADER_OTHER)
+
+static int vde_user_init(void *data, void *dev)
+{
+	struct vde_data *pri = data;
+	VDECONN *conn = NULL;
+	int err = -EINVAL;
+
+	pri->dev = dev;
+
+	conn = vde_open(pri->vde_switch, pri->descr, pri->args);
+
+	if (conn == NULL) {
+		err = -errno;
+		printk(UM_KERN_ERR "vde_user_init: vde_open failed, "
+		       "errno = %d\n", errno);
+		return err;
+	}
+
+	printk(UM_KERN_INFO "vde backend - connection opened\n");
+
+	pri->conn = conn;
+
+	return 0;
+}
+
+static int vde_user_open(void *data)
+{
+	struct vde_data *pri = data;
+
+	if (pri->conn != NULL)
+		return vde_datafd(pri->conn);
+
+	printk(UM_KERN_WARNING "vde_open - we have no VDECONN to open");
+	return -EINVAL;
+}
+
+static void vde_remove(void *data)
+{
+	struct vde_data *pri = data;
+
+	if (pri->conn != NULL) {
+		printk(UM_KERN_INFO "vde backend - closing connection\n");
+		vde_close(pri->conn);
+		pri->conn = NULL;
+		kfree(pri->args);
+		pri->args = NULL;
+		return;
+	}
+
+	printk(UM_KERN_WARNING "vde_remove - we have no VDECONN to remove");
+}
+
+static int vde_set_mtu(int mtu, void *data)
+{
+	return mtu;
+}
+
+const struct net_user_info vde_user_info = {
+	.init		= vde_user_init,
+	.open		= vde_user_open,
+	.close	 	= NULL,
+	.remove	 	= vde_remove,
+	.set_mtu	= vde_set_mtu,
+	.add_address	= NULL,
+	.delete_address = NULL,
+	.max_packet	= MAX_PACKET - ETH_HEADER_OTHER
+};
+
+void vde_init_libstuff(struct vde_data *vpri, struct vde_init *init)
+{
+	struct vde_open_args *args;
+
+	vpri->args = kmalloc(sizeof(struct vde_open_args), UM_GFP_KERNEL);
+	if (vpri->args == NULL) {
+		printk(UM_KERN_ERR "vde_init_libstuff - vde_open_args"
+		       "allocation failed");
+		return;
+	}
+
+	args = vpri->args;
+
+	args->port = init->port;
+	args->group = init->group;
+	args->mode = init->mode ? init->mode : 0700;
+
+	args->port ?  printk(UM_KERN_INFO "port %d", args->port) :
+		printk(UM_KERN_INFO "undefined port");
+}
+
+int vde_user_read(void *conn, void *buf, int len)
+{
+	VDECONN *vconn = conn;
+	int rv;
+
+	if (vconn == NULL)
+		return 0;
+
+	rv = vde_recv(vconn, buf, len, 0);
+	if (rv < 0) {
+		if (errno == EAGAIN)
+			return 0;
+		return -errno;
+	}
+	else if (rv == 0)
+		return -ENOTCONN;
+
+	return rv;
+}
+
+int vde_user_write(void *conn, void *buf, int len)
+{
+	VDECONN *vconn = conn;
+
+	if (vconn == NULL)
+		return 0;
+
+	return vde_send(vconn, buf, len, 0);
+}
+