These changes are the raw update to qemu-2.6.

[kvmfornfv.git] / qemu / hw / block / xen_blkif.h

diff --git a/qemu/hw/block/xen_blkif.h b/qemu/hw/block/xen_blkif.h
index 711b692..c68487c 100644 (file)
--- a/qemu/hw/block/xen_blkif.h
+++ b/qemu/hw/block/xen_blkif.h
@@ -85,8 +85,10 @@ static inline void blkif_get_x86_32_req(blkif_request_t *dst, blkif_x86_32_reque
                d->nr_sectors = s->nr_sectors;
                return;
        }
-       if (n > src->nr_segments)
-               n = src->nr_segments;
+       /* prevent the compiler from optimizing the code and using src->nr_segments instead */
+       barrier();
+       if (n > dst->nr_segments)
+               n = dst->nr_segments;
        for (i = 0; i < n; i++)
                dst->seg[i] = src->seg[i];
 }
@@ -106,8 +108,10 @@ static inline void blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_reque
                d->nr_sectors = s->nr_sectors;
                return;
        }
-       if (n > src->nr_segments)
-               n = src->nr_segments;
+       /* prevent the compiler from optimizing the code and using src->nr_segments instead */
+       barrier();
+       if (n > dst->nr_segments)
+               n = dst->nr_segments;
        for (i = 0; i < n; i++)
                dst->seg[i] = src->seg[i];
 }