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block: access io_plugged with atomic ops 

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-7-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-06-05 14:38:55 +02:00 committed by Fam Zheng
parent e2a6ae7fe5
commit 850d54a2a9
2 changed files with 7 additions and 5 deletions
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4
block/io.c
View File

@ -2645,7 +2645,7 @@ 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);
@ -2658,7 +2658,7 @@ 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);

8
include/block/block_int.h
View File

@ -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;