[PATCH RFC 3/7] migration: multifd_send_kick_main()

[Peter Xu <peterx@redhat.com>]

When a multifd sender thread hit errors, it always needs to kick the main
thread by kicking all the semaphores that it can be waiting upon.

Provide a helper for it and deduplicate the code.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/multifd.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/migration/multifd.c b/migration/multifd.c
index 4afdd88602..33fb21d0e4 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -374,6 +374,18 @@ struct {
     MultiFDMethods *ops;
 } *multifd_send_state;
 
+/*
+ * The migration thread can wait on either of the two semaphores.  This
+ * function can be used to kick the main thread out of waiting on either of
+ * them.  Should mostly only be called when something wrong happened with
+ * the current multifd send thread.
+ */
+static void multifd_send_kick_main(MultiFDSendParams *p)
+{
+    qemu_sem_post(&p->sem_sync);
+    qemu_sem_post(&multifd_send_state->channels_ready);
+}
+
 /*
  * How we use multifd_send_state->pages and channel->pages?
  *
@@ -746,8 +758,7 @@ out:
         assert(local_err);
         trace_multifd_send_error(p->id);
         multifd_send_terminate_threads(local_err);
-        qemu_sem_post(&p->sem_sync);
-        qemu_sem_post(&multifd_send_state->channels_ready);
+        multifd_send_kick_main(p);
         error_free(local_err);
     }
 
@@ -787,8 +798,7 @@ static void multifd_tls_outgoing_handshake(QIOTask *task,
      * is not created, and then tell who pay attention to me.
      */
     p->quit = true;
-    qemu_sem_post(&multifd_send_state->channels_ready);
-    qemu_sem_post(&p->sem_sync);
+    multifd_send_kick_main(p);
     error_free(err);
 }
 
@@ -859,8 +869,7 @@ static void multifd_new_send_channel_cleanup(MultiFDSendParams *p,
 {
      migrate_set_error(migrate_get_current(), err);
      /* Error happen, we need to tell who pay attention to me */
-     qemu_sem_post(&multifd_send_state->channels_ready);
-     qemu_sem_post(&p->sem_sync);
+     multifd_send_kick_main(p);
      /*
       * Although multifd_send_thread is not created, but main migration
       * thread need to judge whether it is running, so we need to mark
-- 
2.41.0