net: xenbus: convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/xenbus.c

@@ -186,7 +186,7 @@ static const struct file_operations xenvif_dbg_io_ring_ops_fops = {
 	.write = xenvif_write_io_ring,
 };
 
-static int xenvif_read_ctrl(struct seq_file *m, void *v)
+static int xenvif_ctrl_show(struct seq_file *m, void *v)
 {
 	struct xenvif *vif = m->private;
 
@@ -194,19 +194,7 @@ static int xenvif_read_ctrl(struct seq_file *m, void *v)
 
 	return 0;
 }
-
-static int xenvif_ctrl_open(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, xenvif_read_ctrl, inode->i_private);
-}
-
-static const struct file_operations xenvif_dbg_ctrl_ops_fops = {
-	.owner = THIS_MODULE,
-	.open = xenvif_ctrl_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(xenvif_ctrl);
 
 static void xenvif_debugfs_addif(struct xenvif *vif)
 {
@@ -238,7 +226,7 @@ static void xenvif_debugfs_addif(struct xenvif *vif)
 						    0400,
 						    vif->xenvif_dbg_root,
 						    vif,
-						    &xenvif_dbg_ctrl_ops_fops);
+						    &xenvif_ctrl_fops);
 			if (IS_ERR_OR_NULL(pfile))
 				pr_warn("Creation of ctrl file returned %ld!\n",
 					PTR_ERR(pfile));