Merge tag 'pull-request-2023-10-20' of https://gitlab.com/thuth/qemu into staging

[mirror_qemu.git] / util / qemu-coroutine-sleep.c

diff --git a/util/qemu-coroutine-sleep.c b/util/qemu-coroutine-sleep.c
index 6966831d370e60f7e707e36205e2ceae5757c2dd..af59f9af9847af2ca1b14217d55aad5d0d15b78e 100644 (file)
--- a/util/qemu-coroutine-sleep.c
+++ b/util/qemu-coroutine-sleep.c
@@ -12,31 +12,68 @@
  */
 
 #include "qemu/osdep.h"
-#include "qemu/coroutine.h"
+#include "qemu/coroutine_int.h"
 #include "qemu/timer.h"
 #include "block/aio.h"
 
-typedef struct CoSleepCB {
-    QEMUTimer *ts;
+static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
+
+void qemu_co_sleep_wake(QemuCoSleep *w)
+{
     Coroutine *co;
-} CoSleepCB;
+
+    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(&co->scheduled,
+                                                qemu_co_sleep_ns__scheduled, NULL);
+
+        assert(scheduled == qemu_co_sleep_ns__scheduled);
+        aio_co_wake(co);
+    }
+}
 
 static void co_sleep_cb(void *opaque)
 {
-    CoSleepCB *sleep_cb = opaque;
-
-    qemu_coroutine_enter(sleep_cb->co, NULL);
+    QemuCoSleep *w = opaque;
+    qemu_co_sleep_wake(w);
 }
 
-void coroutine_fn co_aio_sleep_ns(AioContext *ctx, QEMUClockType type,
-                                  int64_t ns)
+void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
 {
-    CoSleepCB sleep_cb = {
-        .co = qemu_coroutine_self(),
-    };
-    sleep_cb.ts = aio_timer_new(ctx, type, SCALE_NS, co_sleep_cb, &sleep_cb);
-    timer_mod(sleep_cb.ts, qemu_clock_get_ns(type) + ns);
+    Coroutine *co = qemu_coroutine_self();
+
+    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",
+                __func__, scheduled);
+        abort();
+    }
+
+    w->to_wake = co;
     qemu_coroutine_yield();
-    timer_del(sleep_cb.ts);
-    timer_free(sleep_cb.ts);
+
+    /* w->to_wake is cleared before resuming this coroutine.  */
+    assert(w->to_wake == NULL);
+}
+
+void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
+                                            QEMUClockType type, int64_t ns)
+{
+    AioContext *ctx = qemu_get_current_aio_context();
+    QEMUTimer ts;
+
+    aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
+    timer_mod(&ts, qemu_clock_get_ns(type) + ns);
+
+    /*
+     * The timer will fire in the current AiOContext, so the callback
+     * must happen after qemu_co_sleep yields and there is no race
+     * between timer_mod and qemu_co_sleep.
+     */
+    qemu_co_sleep(w);
+    timer_del(&ts);
 }