[Xen-devel] [PATCH v3 1/5] remus: don't call stream_continue() when doing failover

[Wen Congyang <wency@xxxxxxxxxxxxxx>]

stream_continue() is used for migration to read emulator
xenstore data and emulator context. For remus, if we do
failover, we have read it in the checkpoint cycle, and
we only need to complete the stream.

Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libxl/libxl_stream_read.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl_stream_read.c b/tools/libxl/libxl_stream_read.c
index 258dec4..65219d5 100644
--- a/tools/libxl/libxl_stream_read.c
+++ b/tools/libxl/libxl_stream_read.c
@@ -758,6 +758,9 @@ void libxl__xc_domain_restore_done(libxl__egc *egc, void 
*dcs_void,
     libxl__stream_read_state *stream = &dcs->srs;
     STATE_AO_GC(dcs->ao);
 
+    /* convenience aliases */
+    const int checkpointed_stream = dcs->restore_params.checkpointed_stream;
+
     if (rc)
         goto err;
 
@@ -777,11 +780,19 @@ void libxl__xc_domain_restore_done(libxl__egc *egc, void 
*dcs_void,
      * If the stream is not still alive, we must not continue any work.
      */
     if (libxl__stream_read_inuse(stream)) {
-        /*
-         * Libxc has indicated that it is done with the stream.  Resume reading
-         * libxl records from it.
-         */
-        stream_continue(egc, stream);
+        if (checkpointed_stream) {
+            /*
+             * Failover from primary. Domain state is currently at a
+             * consistent checkpoint, ready to go.
+             */
+            stream_complete(egc, stream, 0);
+        } else {
+            /*
+             * Libxc has indicated that it is done with the stream.
+             * Resume reading libxl records from it.
+             */
+            stream_continue(egc, stream);
+        }
     }
 }
 
-- 
2.5.0




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