From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Wed, 25 Aug 2010 19:19:53 +0000 (-0700)
Subject: xenfs/xenbus: report partial reads/writes correctly
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=fb27cfbcbd2865b0e731c4aae47df71778da805e;p=deliverable%2Flinux.git

xenfs/xenbus: report partial reads/writes correctly

copy_(to|from)_user return the number of uncopied bytes, so a successful
return is 0, and any non-zero result indicates some degree of failure.

Reported-by: "Jun Zhu (Intern)" <Jun.Zhu@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---

diff --git a/drivers/xen/xenfs/xenbus.c b/drivers/xen/xenfs/xenbus.c
index 9d5b519d2e4c..d2a905826804 100644
--- a/drivers/xen/xenfs/xenbus.c
+++ b/drivers/xen/xenfs/xenbus.c
@@ -142,7 +142,7 @@ static ssize_t xenbus_file_read(struct file *filp,
 		i += sz - ret;
 		rb->cons += sz - ret;
 
-		if (ret != sz) {
+		if (ret != 0) {
 			if (i == 0)
 				i = -EFAULT;
 			goto out;
@@ -453,7 +453,7 @@ static ssize_t xenbus_file_write(struct file *filp,
 
 	ret = copy_from_user(u->u.buffer + u->len, ubuf, len);
 
-	if (ret == len) {
+	if (ret != 0) {
 		rc = -EFAULT;
 		goto out;
 	}