]> pilppa.com Git - linux-2.6-omap-h63xx.git/commitdiff
virtio_balloon: fix towards_target when deflating balloon
authorAnthony Liguori <aliguori@us.ibm.com>
Mon, 18 Aug 2008 22:15:31 +0000 (17:15 -0500)
committerRusty Russell <rusty@rustcorp.com.au>
Mon, 25 Aug 2008 14:19:25 +0000 (00:19 +1000)
Both v and vb->num_pages are u32 and unsigned int respectively.  If v is less
than vb->num_pages (and it is, when deflating the balloon), the result is a
very large 32-bit number.  Since we're returning a s64, instead of getting the
same negative number we desire, we get a very large positive number.

This handles the case where v < vb->num_pages and ensures we get a small,
negative, s64 as the result.

Rusty: please push this for 2.6.27-rc4.  It's probably appropriate for the
stable tree too as it will cause an unexpected OOM when ballooning.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (simplified)
drivers/virtio/virtio_balloon.c

index bfef604160d16460062f46b84f16c9320579c0d4..62eab43152d21314826838080caed9ad3ee3eb1e 100644 (file)
@@ -158,7 +158,7 @@ static inline s64 towards_target(struct virtio_balloon *vb)
        vb->vdev->config->get(vb->vdev,
                              offsetof(struct virtio_balloon_config, num_pages),
                              &v, sizeof(v));
-       return v - vb->num_pages;
+       return (s64)v - vb->num_pages;
 }
 
 static void update_balloon_size(struct virtio_balloon *vb)