xen/9pfs: fix return value check in xen_9pfs_front_probe()

In case of error, the function xenbus_read() returns ERR_PTR() and never
returns NULL. The NULL test in the return value check should be replaced
with IS_ERR().

Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 71e85643b3f9..83fe487f460e 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -454,8 +454,8 @@ static int xen_9pfs_front_probe(struct xenbus_device *dev,
                         goto error_xenbus;
         }
         priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
-        if (!priv->tag) {
-                ret = -EINVAL;
+        if (IS_ERR(priv->tag)) {
+                ret = PTR_ERR(priv->tag);
                 goto error_xenbus;
         }
         ret = xenbus_transaction_end(xbt, 0);