Index: drivers/net/mlx4/main.c
===================================================================
--- drivers/net/mlx4/main.c	(revision 253096)
+++ drivers/net/mlx4/main.c	(working copy)
@@ -479,11 +479,11 @@
 	int i;
 	int err = 0;
 
-	if (!strcmp(buf, "ib"))
+	if (!strcmp(buf, "ib\n"))
 		info->tmp_type = MLX4_PORT_TYPE_IB;
-	else if (!strcmp(buf, "eth"))
+	else if (!strcmp(buf, "eth\n"))
 		info->tmp_type = MLX4_PORT_TYPE_ETH;
-	else if (!strcmp(buf, "auto"))
+	else if (!strcmp(buf, "auto\n"))
 		info->tmp_type = MLX4_PORT_TYPE_AUTO;
 	else {
 		mlx4_err(mdev, "%s is not supported port type\n", buf);
Index: include/linux/sysfs.h
===================================================================
--- include/linux/sysfs.h	(revision 253096)
+++ include/linux/sysfs.h	(working copy)
@@ -81,37 +81,35 @@
 
 	kobj = arg1;
 	attr = (struct attribute *)arg2;
-	buf = (void *)get_zeroed_page(GFP_KERNEL);
-	len = 1;	/* Copy out a NULL byte at least. */
 	if (kobj->ktype == NULL || kobj->ktype->sysfs_ops == NULL)
 		return (ENODEV);
-	ops = kobj->ktype->sysfs_ops;
+	buf = (void *)get_zeroed_page(GFP_KERNEL);
 	if (buf == NULL)
 		return (ENOMEM);
+	ops = kobj->ktype->sysfs_ops;
 	if (ops->show) {
 		len = ops->show(kobj, attr, buf);
 		/*
-		 * It's valid not to have a 'show' so we just return 1 byte
-		 * of NULL.
+		 * It's valid to not have a 'show' so just return an
+		 * empty string.
 	 	 */
 		if (len < 0) {
 			error = -len;
-			len = 1;
 			if (error != EIO)
 				goto out;
 		}
+
+		/* Trim trailing newline. */
+		len--;
+		buf[len] = '\0';
 	}
-	error = SYSCTL_OUT(req, buf, len);
-	if (error || !req->newptr || ops->store == NULL)
+
+	/* Leave one trailing byte to append a newline. */
+	error = sysctl_handle_string(oidp, buf, PAGE_SIZE - 1, req);
+	if (error != 0 || req->newptr == NULL || ops->store == NULL)
 		goto out;
-	len = req->newlen - req->newidx;
-	if (len >= PAGE_SIZE)
-		error = EINVAL;
-	else 
-		error = SYSCTL_IN(req, buf, len);
-	if (error)
-		goto out;
-	((char *)buf)[len] = '\0';
+	len = strlcat(buf, "\n", PAGE_SIZE);
+	KASSERT(len < PAGE_SIZE, ("new attribute truncated"));
 	len = ops->store(kobj, attr, buf, len);
 	if (len < 0)
 		error = -len;