KVM: correct error-handling code

This code is not executed before file has been initialized to the result of
calling eventfd_fget.  This function returns an ERR_PTR value in an error
case instead of NULL.  Thus the test that file is not NULL is always true.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@match exists@
expression x, E;
statement S1, S2;
@@

x = eventfd_fget(...)
... when != x = E
(
*  if (x == NULL || ...) S1 else S2
|
*  if (x == NULL && ...) S1 else S2
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 99017e8a92ac..bb4ebd89b9ff 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -230,7 +230,7 @@ fail:
         if (eventfd && !IS_ERR(eventfd))
                 eventfd_ctx_put(eventfd);
 
-        if (file && !IS_ERR(file))
+        if (!IS_ERR(file))
                 fput(file);
 
         kfree(irqfd);