X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Fhw%2Fblock%2Fxen_blkif.h;fp=qemu%2Fhw%2Fblock%2Fxen_blkif.h;h=c68487cb31f5e2412b0a618446f4f4317529c16b;hb=437fd90c0250dee670290f9b714253671a990160;hp=711b69274255bedda4b5d51901e372757e78883a;hpb=5bbd6fe9b8bab2a93e548c5a53b032d1939eec05;p=kvmfornfv.git

diff --git a/qemu/hw/block/xen_blkif.h b/qemu/hw/block/xen_blkif.h
index 711b69274..c68487cb3 100644
--- 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];
 }