From: Juan Quintela <quintela@redhat.com>
Date: Fri, 4 Jan 2019 18:12:35 +0000 (+0100)
Subject: multifd: Only send pages when packet are not empty
X-Git-Tag: v4.0.0-rc1~8^2~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ad24c7cb595e7ff3df17f7db790e2a7dfaf8040c;p=thirdparty%2Fqemu.git

multifd: Only send pages when packet are not empty

We send packages without pages sometimes for sysnchronizanion.  The
iov functions do the right thing, but we will be changing this code in
future patches.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---

diff --git a/migration/ram.c b/migration/ram.c
index 35bd6213e91..3034f862c14 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1088,9 +1088,12 @@ static void *multifd_send_thread(void *opaque)
                 break;
             }
 
-            ret = qio_channel_writev_all(p->c, p->pages->iov, used, &local_err);
-            if (ret != 0) {
-                break;
+            if (used) {
+                ret = qio_channel_writev_all(p->c, p->pages->iov,
+                                             used, &local_err);
+                if (ret != 0) {
+                    break;
+                }
             }
 
             qemu_mutex_lock(&p->mutex);
@@ -1317,9 +1320,12 @@ static void *multifd_recv_thread(void *opaque)
         p->num_pages += used;
         qemu_mutex_unlock(&p->mutex);
 
-        ret = qio_channel_readv_all(p->c, p->pages->iov, used, &local_err);
-        if (ret != 0) {
-            break;
+        if (used) {
+            ret = qio_channel_readv_all(p->c, p->pages->iov,
+                                        used, &local_err);
+            if (ret != 0) {
+                break;
+            }
         }
 
         if (flags & MULTIFD_FLAG_SYNC) {