[Qemu-devel] [PATCH] vhost-net: Move asserts to after check for end < start

[Bruce Rogers <brogers@suse.com>]

When migrating a vm using vhost-net we hit the following assertion:

qemu-kvm: /usr/src/packages/BUILD/qemu-kvm-0.15.1/hw/vhost.c:30:
vhost_dev_sync_region: Assertion `start / (0x1000 * (8 *
sizeof(vhost_log_chunk_t))) < dev->log_size' failed.

The cases which the end < start check is intended to catch, such as
for vga video memory, will also likely trigger the assertion.
Reorder the code to handle this correctly.

Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/vhost.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/vhost.c b/hw/vhost.c
index 0870cb7..7309f71 100644
--- a/hw/vhost.c
+++ b/hw/vhost.c
@@ -26,11 +26,11 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
     vhost_log_chunk_t *to = dev->log + end / VHOST_LOG_CHUNK + 1;
     uint64_t addr = (start / VHOST_LOG_CHUNK) * VHOST_LOG_CHUNK;
 
-    assert(end / VHOST_LOG_CHUNK < dev->log_size);
-    assert(start / VHOST_LOG_CHUNK < dev->log_size);
     if (end < start) {
         return;
     }
+    assert(end / VHOST_LOG_CHUNK < dev->log_size);
+    assert(start / VHOST_LOG_CHUNK < dev->log_size);
     for (;from < to; ++from) {
         vhost_log_chunk_t log;
         int bit;
-- 
1.7.7