virtio-9p: use QEMU thread pool

The QEMU thread pool already has a mechanism to invoke callbacks in the main
thread.  It does not need an EventNotifier and it is more efficient too.
Use it instead of GAsyncQueue + GThreadPool + glue.

As a side effect, it silences Coverity's complaint about an unchecked
return value for event_notifier_init.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
(removed no more needed #include <glib.h> from virtio-9p-coth.h)
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

hw/9pfs/virtio-9p-coth.c

@@ -12,71 +12,30 @@
  *
  */
 
-#include "fsdev/qemu-fsdev.h"
-#include "qemu/thread.h"
-#include "qemu/event_notifier.h"
+#include "qemu-common.h"
+#include "block/thread-pool.h"
 #include "qemu/coroutine.h"
+#include "qemu/main-loop.h"
 #include "virtio-9p-coth.h"
 
-/* v9fs glib thread pool */
-static V9fsThPool v9fs_pool;
-
-void co_run_in_worker_bh(void *opaque)
+/* Called from QEMU I/O thread.  */
+static void coroutine_enter_cb(void *opaque, int ret)
 {
     Coroutine *co = opaque;
-    g_thread_pool_push(v9fs_pool.pool, co, NULL);
-}
-
-static void v9fs_qemu_process_req_done(EventNotifier *e)
-{
-    Coroutine *co;
-
-    event_notifier_test_and_clear(e);
-
-    while ((co = g_async_queue_try_pop(v9fs_pool.completed)) != NULL) {
-        qemu_coroutine_enter(co, NULL);
-    }
+    qemu_coroutine_enter(co, NULL);
 }
 
-static void v9fs_thread_routine(gpointer data, gpointer user_data)
+/* Called from worker thread.  */
+static int coroutine_enter_func(void *arg)
 {
-    Coroutine *co = data;
-
+    Coroutine *co = arg;
     qemu_coroutine_enter(co, NULL);
-
-    g_async_queue_push(v9fs_pool.completed, co);
-
-    event_notifier_set(&v9fs_pool.e);
+    return 0;
 }
 
-int v9fs_init_worker_threads(void)
+void co_run_in_worker_bh(void *opaque)
 {
-    int ret = 0;
-    V9fsThPool *p = &v9fs_pool;
-    sigset_t set, oldset;
-
-    sigfillset(&set);
-    /* Leave signal handling to the iothread.  */
-    pthread_sigmask(SIG_SETMASK, &set, &oldset);
-
-    p->pool = g_thread_pool_new(v9fs_thread_routine, p, -1, FALSE, NULL);
-    if (!p->pool) {
-        ret = -1;
-        goto err_out;
-    }
-    p->completed = g_async_queue_new();
-    if (!p->completed) {
-        /*
-         * We are going to terminate.
-         * So don't worry about cleanup
-         */
-        ret = -1;
-        goto err_out;
-    }
-    event_notifier_init(&p->e, 0);
-
-    event_notifier_set_handler(&p->e, v9fs_qemu_process_req_done);
-err_out:
-    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
-    return ret;
+    Coroutine *co = opaque;
+    thread_pool_submit_aio(qemu_get_aio_context()->thread_pool,
+                           coroutine_enter_func, co, coroutine_enter_cb, co);
 }

hw/9pfs/virtio-9p-coth.h

@@ -18,14 +18,6 @@
 #include "qemu/thread.h"
 #include "qemu/coroutine.h"
 #include "virtio-9p.h"
-#include <glib.h>
-
-typedef struct V9fsThPool {
-    EventNotifier e;
-
-    GThreadPool *pool;
-    GAsyncQueue *completed;
-} V9fsThPool;
 
 /*
  * we want to use bottom half because we want to make sure the below
@@ -45,7 +37,7 @@ typedef struct V9fsThPool {
         qemu_bh_schedule(co_bh);                                        \
         /*                                                              \
          * yield in qemu thread and re-enter back                       \
-         * in glib worker thread                                        \
+         * in worker thread                                             \
          */                                                             \
         qemu_coroutine_yield();                                         \
         qemu_bh_delete(co_bh);                                          \

hw/9pfs/virtio-9p-device.c

@@ -116,10 +116,6 @@ static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
                    " and export path:%s", s->fsconf.fsdev_id, s->ctx.fs_root);
         goto out;
     }
-    if (v9fs_init_worker_threads() < 0) {
-        error_setg(errp, "worker thread initialization failed");
-        goto out;
-    }
 
     /*
      * Check details of export path, We need to use fs driver