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authorAnthony Liguori <aliguori@us.ibm.com>2008-08-18 17:15:31 -0500
committerRusty Russell <rusty@rustcorp.com.au>2008-08-26 00:19:25 +1000
commit532a6086e35fa3b5761e68af36d4e42a550eba15 (patch)
treec1d8ab4df9db25e0efd89dab64dda98f84df1fa6 /drivers/virtio
parent83097aca8567a0bd593534853b71fe0fa9a75d69 (diff)
downloadlinux-532a6086e35fa3b5761e68af36d4e42a550eba15.tar.gz
virtio_balloon: fix towards_target when deflating balloon
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)
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_balloon.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index bfef604160d1..62eab43152d2 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -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)