[Qemu-devel] [PATCH RFC 02/14] qemu aio: prepare for supporting selective bypass coroutine

[Ming Lei <ming.lei@canonical.com>]

If device thinks that it isn't necessary to apply coroutine
in its performance sensitive path, it can call
qemu_aio_set_bypass_co(false) to bypass the coroutine which
has supported bypass mode and just call the function directly.

One example is virtio-blk dataplane.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 async.c             |    1 +
 include/block/aio.h |   13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/async.c b/async.c
index 34af0b2..251a074 100644
--- a/async.c
+++ b/async.c
@@ -293,6 +293,7 @@ AioContext *aio_context_new(void)
                            (EventNotifierHandler *)
                            event_notifier_test_and_clear);
     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
+    qemu_aio_set_bypass_co(ctx, false);
 
     return ctx;
 }
diff --git a/include/block/aio.h b/include/block/aio.h
index c23de3c..48d827e 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -87,6 +87,9 @@ struct AioContext {
 
     /* TimerLists for calling timers - one per clock type */
     QEMUTimerListGroup tlg;
+
+    /* support selective bypass coroutine */
+    bool bypass_co;
 };
 
 /* Used internally to synchronize aio_poll against qemu_bh_schedule.  */
@@ -303,4 +306,14 @@ static inline void aio_timer_init(AioContext *ctx,
     timer_init(ts, ctx->tlg.tl[type], scale, cb, opaque);
 }
 
+static inline void qemu_aio_set_bypass_co(AioContext *ctx, bool bypass)
+{
+    ctx->bypass_co = bypass;
+}
+
+static inline bool qemu_aio_get_bypass_co(AioContext *ctx)
+{
+    return ctx->bypass_co;
+}
+
 #endif
-- 
1.7.9.5