diff mbox

[06/18] block: access io_plugged with atomic ops

Message ID 20170525163225.29954-7-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini May 25, 2017, 4:32 p.m. UTC 
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/io.c                | 4 ++--
 include/block/block_int.h | 8 +++++---
 2 files changed, 7 insertions(+), 5 deletions(-)
diff mbox

Patch

diff --git a/block/io.c b/block/io.c
index 3a98b02..f34d030 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2658,7 +2658,7 @@  void bdrv_io_plug(BlockDriverState *bs)
         bdrv_io_plug(child->bs);
     }
 
-    if (bs->io_plugged++ == 0) {
+    if (atomic_fetch_inc(&bs->io_plugged) == 0) {
         BlockDriver *drv = bs->drv;
         if (drv && drv->bdrv_io_plug) {
             drv->bdrv_io_plug(bs);
@@ -2671,7 +2671,7 @@  void bdrv_io_unplug(BlockDriverState *bs)
     BdrvChild *child;
 
     assert(bs->io_plugged);
-    if (--bs->io_plugged == 0) {
+    if (atomic_fetch_dec(&bs->io_plugged) == 1) {
         BlockDriver *drv = bs->drv;
         if (drv && drv->bdrv_io_unplug) {
             drv->bdrv_io_unplug(bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b690e58..d54ed75 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -611,9 +611,6 @@  struct BlockDriverState {
     uint64_t write_threshold_offset;
     NotifierWithReturn write_threshold_notifier;
 
-    /* counter for nested bdrv_io_plug */
-    unsigned io_plugged;
-
     QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
     CoQueue flush_queue;                  /* Serializing flush queue */
     bool active_flush_req;                /* Flush request in flight? */
@@ -639,6 +636,11 @@  struct BlockDriverState {
      */
     bool wakeup;
 
+    /* counter for nested bdrv_io_plug.
+     * Accessed with atomic ops.
+    */
+    unsigned io_plugged;
+
     /* do we need to tell the quest if we have a volatile write cache? */
     int enable_write_cache;