Replace with an explicit barrier and a comment.
Reviewed-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
---
util/qemu-coroutine.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
index 849452369201..17a88f65053e 100644
--- a/util/qemu-coroutine.c
+++ b/util/qemu-coroutine.c
@@ -127,9 +127,13 @@ void qemu_aio_coroutine_enter(AioContext *ctx, Coroutine
*co)
Coroutine *to = QSIMPLEQ_FIRST(&pending);
CoroutineAction ret;
- /* Cannot rely on the read barrier for to in aio_co_wake(), as there
are
- * callers outside of aio_co_wake() */
- const char *scheduled = qatomic_mb_read(&to->scheduled);
+ /*
+ * Read to before to->scheduled; pairs with qatomic_cmpxchg in
+ * qemu_co_sleep(), aio_co_schedule() etc.
+ */
+ smp_read_barrier_depends();
+
+ const char *scheduled = qatomic_read(&to->scheduled);
QSIMPLEQ_REMOVE_HEAD(&pending, co_queue_next);
--
2.40.0
