Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/io.c                |  6 +++---
 include/block/block_int.h | 10 ++++++----
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/block/io.c b/block/io.c
index 3a27fd5..869322a 100644
--- a/block/io.c
+++ b/block/io.c
@@ -375,7 +375,7 @@ void bdrv_drain_all(void)
 static void tracked_request_end(BdrvTrackedRequest *req)
 {
     if (req->serialising) {
-        req->bs->serialising_in_flight--;
+        atomic_dec(&req->bs->serialising_in_flight);
     }
 
     QLIST_REMOVE(req, list);
@@ -414,7 +414,7 @@ static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
                                - overlap_offset;
 
     if (!req->serialising) {
-        req->bs->serialising_in_flight++;
+        atomic_inc(&req->bs->serialising_in_flight);
         req->serialising = true;
     }
 
@@ -519,7 +519,7 @@ static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
     bool retry;
     bool waited = false;
 
-    if (!bs->serialising_in_flight) {
+    if (!atomic_read(&bs->serialising_in_flight)) {
         return false;
     }
 
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a43fe78..7317db6 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -590,10 +590,6 @@ struct BlockDriverState {
     /* Callback before write request is processed */
     NotifierWithReturnList before_write_notifiers;
 
-    /* number of in-flight requests; overall and serialising */
-    unsigned int in_flight;
-    unsigned int serialising_in_flight;
-
     bool wakeup;
 
     /* Offset after the highest byte written to */
@@ -620,6 +616,12 @@ struct BlockDriverState {
      */
     int copy_on_read;
 
+    /* number of in-flight requests; overall and serialising.
+     * Accessed with atomic ops.
+     */
+    unsigned int in_flight;
+    unsigned int serialising_in_flight;
+
     /* do we need to tell the quest if we have a volatile write cache? */
     int enable_write_cache;
 
-- 
2.9.3

On Thu, Apr 20, 2017 at 02:00:45PM +0200, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/io.c                |  6 +++---
>  include/block/block_int.h | 10 ++++++----
>  2 files changed, 9 insertions(+), 7 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>