[PULL 12/12] migration/migration.c: Fix hang in ram_save_host_page

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Lukas Straub <lukasstraub2@web.de>

migration_rate_limit will erroneously ratelimit a shutdown socket,
which causes the migration thread to hang in ram_save_host_page
if the socket is shutdown.

Fix this by explicitly testing if the socket has errors or was
shutdown in migration_rate_limit.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Message-Id: <e79085bbe2d46dfa007dd41820194d5e2d4fcd80.1590007004.git.lukasstraub2@web.de>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/migration.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index 0bb042a0f7..b63ad91d34 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3361,6 +3361,10 @@ bool migration_rate_limit(void)
     bool urgent = false;
     migration_update_counters(s, now);
     if (qemu_file_rate_limit(s->to_dst_file)) {
+
+        if (qemu_file_get_error(s->to_dst_file)) {
+            return false;
+        }
         /*
          * Wait for a delay to do rate limiting OR
          * something urgent to post the semaphore.
-- 
2.26.2