[PATCH RFC 6/7] migration: Split multifd pending_job into two booleans

[Peter Xu <peterx@redhat.com>]

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/multifd.h | 16 ++++++++++------
 migration/multifd.c | 33 +++++++++++++++++++++++----------
 2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/migration/multifd.h b/migration/multifd.h
index 2acf400085..ddee7b8d8a 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -101,12 +101,16 @@ typedef struct {
     uint32_t flags;
     /* global number of generated multifd packets */
     uint64_t packet_num;
-    /* thread has work to do */
-    int pending_job;
-    /* array of pages to sent.
-     * The owner of 'pages' depends of 'pending_job' value:
-     * pending_job == 0 -> migration_thread can use it.
-     * pending_job != 0 -> multifd_channel can use it.
+    /* thread has a request to sync all data */
+    bool pending_sync;
+    /* thread has something to send */
+    bool pending_job;
+    /*
+     * Array of pages to sent. The owner of 'pages' depends of
+     * 'pending_job' value:
+     *
+     *   - true -> multifd_channel owns it.
+     *   - false -> migration_thread owns it.
      */
     MultiFDPages_t *pages;
 
diff --git a/migration/multifd.c b/migration/multifd.c
index 8140520843..fe8d746ff9 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -425,7 +425,7 @@ static int multifd_send_pages(QEMUFile *f)
         p = &multifd_send_state->params[i];
         qemu_mutex_lock(&p->mutex);
         if (!p->pending_job) {
-            p->pending_job++;
+            p->pending_job = true;
             next_channel = (i + 1) % migrate_multifd_channels();
             break;
         }
@@ -615,8 +615,7 @@ int multifd_send_sync_main(QEMUFile *f)
 
         qemu_mutex_lock(&p->mutex);
         p->packet_num = multifd_send_state->packet_num++;
-        p->flags |= MULTIFD_FLAG_SYNC;
-        p->pending_job++;
+        p->pending_sync = true;
         qemu_mutex_unlock(&p->mutex);
         qemu_sem_post(&p->sem);
     }
@@ -747,8 +746,6 @@ static void *multifd_send_thread(void *opaque)
 
         qemu_mutex_lock(&p->mutex);
         if (p->pending_job) {
-            bool need_sync = p->flags & MULTIFD_FLAG_SYNC;
-
             if (!multifd_send_prepare(p, &local_err)) {
                 assert(local_err);
                 qemu_mutex_unlock(&p->mutex);
@@ -764,12 +761,27 @@ static void *multifd_send_thread(void *opaque)
             qemu_mutex_lock(&p->mutex);
 
             /* Send successful, mark the task completed */
-            p->pending_job--;
+            p->pending_job = false;
+
+        } else if (p->pending_sync) {
+            p->flags |= MULTIFD_FLAG_SYNC;
+
+            if (!multifd_send_prepare(p, &local_err)) {
+                assert(local_err);
+                qemu_mutex_unlock(&p->mutex);
+                goto out;
+            }
 
-            /* If this is a sync task, we need one more kick */
-            if (need_sync) {
-                qemu_sem_post(&p->sem_sync);
+            /* Send the packets without mutex */
+            qemu_mutex_unlock(&p->mutex);
+            if (!multifd_do_send(p, &local_err)) {
+                assert(local_err);
+                goto out;
             }
+            qemu_mutex_lock(&p->mutex);
+
+            qemu_sem_post(&p->sem_sync);
+            p->pending_sync = false;
         }
         qemu_mutex_unlock(&p->mutex);
     }
@@ -932,7 +944,8 @@ int multifd_save_setup(Error **errp)
         qemu_mutex_init(&p->mutex);
         qemu_sem_init(&p->sem, 0);
         qemu_sem_init(&p->sem_sync, 0);
-        p->pending_job = 0;
+        p->pending_job = false;
+        p->pending_sync = false;
         p->id = i;
         p->pages = multifd_pages_init(page_count);
         p->packet_len = sizeof(MultiFDPacket_t)
-- 
2.41.0