coroutine-sleep: replace QemuCoSleepState pointer with struct in the API

Right now, users of qemu_co_sleep_ns_wakeable are simply passing
a pointer to QemuCoSleepState by reference to the function.  But
QemuCoSleepState really is just a Coroutine*; making the
content of the struct public is just as efficient and lets us
skip the user_state_pointer indirection.

Since the usage is changed, take the occasion to rename the
struct to QemuCoSleep.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-6-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 18 insertions, 23 deletions

diff --git a/util/qemu-coroutine-sleep.c b/util/qemu-coroutine-sleep.c
index 1d25019..89c3b75 100644
--- a/util/qemu-coroutine-sleep.c
+++ b/util/qemu-coroutine-sleep.c
@@ -19,42 +19,37 @@
 
 static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
 
-struct QemuCoSleepState {
+void qemu_co_sleep_wake(QemuCoSleep *w)
+{
     Coroutine *co;
-    QemuCoSleepState **user_state_pointer;
-};
 
-void qemu_co_sleep_wake(QemuCoSleepState *sleep_state)
-{
-    if (sleep_state) {
+    co = w->to_wake;
+    w->to_wake = NULL;
+    if (co) {
         /* Write of schedule protected by barrier write in aio_co_schedule */
-        const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled,
+        const char *scheduled = qatomic_cmpxchg(&co->scheduled,
                                                 qemu_co_sleep_ns__scheduled, NULL);
 
         assert(scheduled == qemu_co_sleep_ns__scheduled);
-        *sleep_state->user_state_pointer = NULL;
-        aio_co_wake(sleep_state->co);
+        aio_co_wake(co);
     }
 }
 
 static void co_sleep_cb(void *opaque)
 {
-    QemuCoSleepState **sleep_state = opaque;
-    qemu_co_sleep_wake(*sleep_state);
+    QemuCoSleep *w = opaque;
+    qemu_co_sleep_wake(w);
 }
 
-void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
-                                            QemuCoSleepState **sleep_state)
+void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
+                                            QEMUClockType type, int64_t ns)
 {
+    Coroutine *co = qemu_coroutine_self();
     AioContext *ctx = qemu_get_current_aio_context();
     QEMUTimer ts;
-    QemuCoSleepState state = {
-        .co = qemu_coroutine_self(),
-        .user_state_pointer = sleep_state,
-    };
 
-    const char *scheduled = qatomic_cmpxchg(&state.co->scheduled, NULL,
-                                           qemu_co_sleep_ns__scheduled);
+    const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
+                                            qemu_co_sleep_ns__scheduled);
     if (scheduled) {
         fprintf(stderr,
                 "%s: Co-routine was already scheduled in '%s'\n",
@@ -62,12 +57,12 @@ void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
         abort();
     }
 
-    aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, sleep_state);
-    *sleep_state = &state;
+    w->to_wake = co;
+    aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w),
     timer_mod(&ts, qemu_clock_get_ns(type) + ns);
     qemu_coroutine_yield();
     timer_del(&ts);
 
-    /* qemu_co_sleep_wake clears *sleep_state before resuming this coroutine.  */
-    assert(*sleep_state == NULL);
+    /* w->to_wake is cleared before resuming this coroutine.  */
+    assert(w->to_wake == NULL);
 }