[PATCH 4/7] colo: fixed 'Segmentation fault' when the simplex mode PVM poweroff

[Lei Rao <lei.rao@intel.com>]

From: "Rao, Lei" <lei.rao@intel.com>

When a PVM completed its SVM failover steps and begins to run in
the simplex mode, QEMU would encounter a 'Segmentation fault' if
the guest poweroff with the following calltrace:

Program received signal SIGSEGV, Segmentation fault.

This is because primary_vm_do_failover() would call "qemu_file_shutdown
(s->rp_state.from_dst_file);" and later the migration_shutdown() would
do it again. So, we should set the s->rp_state.from_dst_file to NULL.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Lei Rao <lei.rao@intel.com>
---
 migration/colo.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 616dc00..c25e488 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -156,14 +156,15 @@ static void primary_vm_do_failover(void)
 
     /*
      * Wake up COLO thread which may blocked in recv() or send(),
-     * The s->rp_state.from_dst_file and s->to_dst_file may use the
-     * same fd, but we still shutdown the fd for twice, it is harmless.
+     * The s->to_dst_file may use the same fd, but we still shutdown
+     * the fd for twice, it is harmless.
      */
     if (s->to_dst_file) {
         qemu_file_shutdown(s->to_dst_file);
     }
     if (s->rp_state.from_dst_file) {
         qemu_file_shutdown(s->rp_state.from_dst_file);
+        s->rp_state.from_dst_file = NULL;
     }
 
     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
-- 
1.8.3.1