Subject: [PATCH 17/46] rdma: allow state transitions between other states besides ACTIVE

From: Nigel Croxon <[email-masked]>
Date: Thu, 14 Nov 2013 22:52:53 +0100

RH-Author: Nigel Croxon <[email-masked]>
Message-id: <[email-masked]>
Patchwork-id: 55705
O-Subject: [RHEL7.0 PATCH 17/42] rdma: allow state transitions between other states besides ACTIVE
Bugzilla: 1011720
RH-Acked-by: Orit Wasserman <[email-masked]>
RH-Acked-by: Amit Shah <[email-masked]>
RH-Acked-by: Paolo Bonzini <[email-masked]>

Bugzilla: 1011720
https://bugzilla.redhat.com/show_bug.cgi?id=1011720

>From commit ID:
commit d58f574bf39796ed2396dfd1e308352fbb03f944
Author: Michael R. Hines <[email-masked]>
Date:   Mon Jul 22 10:01:56 2013 -0400

    rdma: allow state transitions between other states besides ACTIVE

    This patch is in preparation for the next ones: Until now the MIG_STATE_SETUP
    state was not really a 'formal' state. It has been used as a 'zero' state
    and QEMU has been unconditionally transitioning into this state when
    the QMP migrate command was called. In preparation for timing this state,
    we have to make this state a a 'real' state which actually gets transitioned
    from later in the migration_thread() from SETUP => ACTIVE, rather than just
    automatically dropping into this state at the beginninig of the migration.

    This means that the state transition function (migration_finish_set_state())
    needs to be capable of transitioning from valid states _other_ than just
    MIG_STATE_ACTIVE.

    The function is in fact already capable of doing that, but was not allowing the
    old state to be a parameter specified as an input.

    This patch fixes that and only makes the transition if the current state
    matches the old state that the caller intended to transition from.

    Reviewed-by: Juan Quintela <[email-masked]>
    Tested-by: Michael R. Hines <[email-masked]>
    Signed-off-by: Michael R. Hines <[email-masked]>
    Signed-off-by: Juan Quintela <[email-masked]>
---
 migration.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

Signed-off-by: Michal Novotny <[email-masked]>
---
 migration.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/migration.c b/migration.c
index 2fa0237..e885bb7 100644
--- a/migration.c
+++ b/migration.c
@@ -296,9 +296,9 @@ static void migrate_fd_cleanup(void *opaque)
     notifier_list_notify(&migration_state_notifiers, s);
 }
 
-static void migrate_finish_set_state(MigrationState *s, int new_state)
+static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 {
-    if (atomic_cmpxchg(&s->state, MIG_STATE_ACTIVE, new_state) == new_state) {
+    if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
         trace_migrate_set_state(new_state);
     }
 }
@@ -316,7 +316,7 @@ static void migrate_fd_cancel(MigrationState *s)
 {
     DPRINTF("cancelling migration\n");
 
-    migrate_finish_set_state(s, MIG_STATE_CANCELLED);
+    migrate_set_state(s, s->state, MIG_STATE_CANCELLED);
 }
 
 void add_migration_state_change_notifier(Notifier *notify)
@@ -578,19 +578,19 @@ static void *migration_thread(void *opaque)
                 qemu_mutex_unlock_iothread();
 
                 if (ret < 0) {
-                    migrate_finish_set_state(s, MIG_STATE_ERROR);
+                    migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
                     break;
                 }
 
                 if (!qemu_file_get_error(s->file)) {
-                    migrate_finish_set_state(s, MIG_STATE_COMPLETED);
+                    migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
                     break;
                 }
             }
         }
 
         if (qemu_file_get_error(s->file)) {
-            migrate_finish_set_state(s, MIG_STATE_ERROR);
+            migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
             break;
         }
         current_time = qemu_get_clock_ms(rt_clock);
-- 
1.7.11.7