tun: export skb_array

This patch exports skb_array through tun_get_skb_array(). Caller can
then manipulate skb array directly.
Signed-off-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -2626,6 +2626,19 @@ struct socket *tun_get_socket(struct file *file)
 }
 EXPORT_SYMBOL_GPL(tun_get_socket);
 
+struct skb_array *tun_get_skb_array(struct file *file)
+{
+	struct tun_file *tfile;
+
+	if (file->f_op != &tun_fops)
+		return ERR_PTR(-EINVAL);
+	tfile = file->private_data;
+	if (!tfile)
+		return ERR_PTR(-EBADFD);
+	return &tfile->tx_array;
+}
+EXPORT_SYMBOL_GPL(tun_get_skb_array);
+
 module_init(tun_init);
 module_exit(tun_cleanup);
 MODULE_DESCRIPTION(DRV_DESCRIPTION);

include/linux/if_tun.h

@@ -19,6 +19,7 @@
 
 #if defined(CONFIG_TUN) || defined(CONFIG_TUN_MODULE)
 struct socket *tun_get_socket(struct file *);
+struct skb_array *tun_get_skb_array(struct file *file);
 #else
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -28,5 +29,9 @@ static inline struct socket *tun_get_socket(struct file *f)
 {
 	return ERR_PTR(-EINVAL);
 }
+static inline struct skb_array *tun_get_skb_array(struct file *f)
+{
+	return ERR_PTR(-EINVAL);
+}
 #endif /* CONFIG_TUN */
 #endif /* __IF_TUN_H */