diff options
Diffstat (limited to 'util/async.c')
| -rw-r--r-- | util/async.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/util/async.c b/util/async.c index b94518b948..3165a28f2f 100644 --- a/util/async.c +++ b/util/async.c @@ -249,7 +249,14 @@ aio_ctx_prepare(GSource *source, gint *timeout) { AioContext *ctx = (AioContext *) source; - atomic_or(&ctx->notify_me, 1); + atomic_set(&ctx->notify_me, atomic_read(&ctx->notify_me) | 1); + + /* + * Write ctx->notify_me before computing the timeout + * (reading bottom half flags, etc.). Pairs with + * smp_mb in aio_notify(). + */ + smp_mb(); /* We assume there is no timeout already supplied */ *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)); @@ -268,7 +275,8 @@ aio_ctx_check(GSource *source) QEMUBH *bh; BHListSlice *s; - atomic_and(&ctx->notify_me, ~1); + /* Finish computing the timeout before clearing the flag. */ + atomic_store_release(&ctx->notify_me, atomic_read(&ctx->notify_me) & ~1); aio_notify_accept(ctx); QSLIST_FOREACH_RCU(bh, &ctx->bh_list, next) { @@ -411,10 +419,10 @@ LuringState *aio_get_linux_io_uring(AioContext *ctx) void aio_notify(AioContext *ctx) { /* Write e.g. bh->scheduled before reading ctx->notify_me. Pairs - * with atomic_or in aio_ctx_prepare or atomic_add in aio_poll. + * with smp_mb in aio_ctx_prepare or aio_poll. */ smp_mb(); - if (ctx->notify_me) { + if (atomic_read(&ctx->notify_me)) { event_notifier_set(&ctx->notifier); atomic_mb_set(&ctx->notified, true); } |