vhost: fix get_user_pages_fast error handling
get_user_pages_fast returns number of pages on success, negative value
on failure, but never 0. Fix vhost code to match this logic.
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6c31c0c..7cd55e0 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -646,8 +646,9 @@
int bit = nr + (log % PAGE_SIZE) * 8;
int r;
r = get_user_pages_fast(log, 1, 1, &page);
- if (r)
+ if (r < 0)
return r;
+ BUG_ON(r != 1);
base = kmap_atomic(page, KM_USER0);
set_bit(bit, base);
kunmap_atomic(base, KM_USER0);