diff options
Diffstat (limited to 'async.c')
| -rw-r--r-- | async.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/async.c b/async.c index 5b6fe6b4cc..34af0b25ca 100644 --- a/async.c +++ b/async.c @@ -26,6 +26,7 @@ #include "block/aio.h" #include "block/thread-pool.h" #include "qemu/main-loop.h" +#include "qemu/atomic.h" /***********************************************************/ /* bottom halves (can be seen as timers which expire ASAP) */ @@ -247,9 +248,25 @@ ThreadPool *aio_get_thread_pool(AioContext *ctx) return ctx->thread_pool; } +void aio_set_dispatching(AioContext *ctx, bool dispatching) +{ + ctx->dispatching = dispatching; + if (!dispatching) { + /* Write ctx->dispatching before reading e.g. bh->scheduled. + * Optimization: this is only needed when we're entering the "unsafe" + * phase where other threads must call event_notifier_set. + */ + smp_mb(); + } +} + void aio_notify(AioContext *ctx) { - event_notifier_set(&ctx->notifier); + /* Write e.g. bh->scheduled before reading ctx->dispatching. */ + smp_mb(); + if (!ctx->dispatching) { + event_notifier_set(&ctx->notifier); + } } static void aio_timerlist_notify(void *opaque) |