migration: Remove not needed semaphore and quit

We know quit with shutdwon in the QIO.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
--
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Use shutdown() instead of unref()

migration/ram.c

@@ -594,14 +594,10 @@ typedef struct {
     QemuThread thread;
     /* communication channel */
     QIOChannel *c;
-    /* sem where to wait for more work */
-    QemuSemaphore sem;
     /* this mutex protects the following parameters */
     QemuMutex mutex;
     /* is this channel thread running */
     bool running;
-    /* should this thread finish */
-    bool quit;
     /* array of pages to receive */
     MultiFDPages_t *pages;
     /* packet allocated len */
@@ -1144,8 +1140,11 @@ static void multifd_recv_terminate_threads(Error *err)
         MultiFDRecvParams *p = &multifd_recv_state->params[i];
 
         qemu_mutex_lock(&p->mutex);
-        p->quit = true;
-        qemu_sem_post(&p->sem);
+        /* We could arrive here for two reasons:
+           - normal quit, i.e. everything went fine, just finished
+           - error quit: We close the channels so the channel threads
+             finish the qio_channel_read_all_eof() */
+        qio_channel_shutdown(p->c, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
         qemu_mutex_unlock(&p->mutex);
     }
 }
@@ -1168,7 +1167,6 @@ int multifd_load_cleanup(Error **errp)
         object_unref(OBJECT(p->c));
         p->c = NULL;
         qemu_mutex_destroy(&p->mutex);
-        qemu_sem_destroy(&p->sem);
         qemu_sem_destroy(&p->sem_sync);
         g_free(p->name);
         p->name = NULL;
@@ -1291,9 +1289,7 @@ int multifd_load_setup(void)
         MultiFDRecvParams *p = &multifd_recv_state->params[i];
 
         qemu_mutex_init(&p->mutex);
-        qemu_sem_init(&p->sem, 0);
         qemu_sem_init(&p->sem_sync, 0);
-        p->quit = false;
         p->id = i;
         p->pages = multifd_pages_init(page_count);
         p->packet_len = sizeof(MultiFDPacket_t)