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[v7,10/23] migration: wakeup dst ram-load-thread for recover

Message ID 20180309091535.13315-11-peterx@redhat.com
State New
Headers show
Series Migration: postcopy failure recovery | expand

Commit Message

Peter Xu March 9, 2018, 9:15 a.m. UTC 
On the destination side, we cannot wake up all the threads when we got
reconnected. The first thing to do is to wake up the main load thread,
so that we can continue to receive valid messages from source again and
reply when needed.

At this point, we switch the destination VM state from postcopy-paused
back to postcopy-recover.

Now we are finally ready to do the resume logic.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)
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Patch

diff --git a/migration/migration.c b/migration/migration.c
index 322d5ad79b..bbeb156a39 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -429,8 +429,34 @@  static void migration_incoming_process(void)
 
 void migration_fd_process_incoming(QEMUFile *f)
 {
-    migration_incoming_setup(f);
-    migration_incoming_process();
+    MigrationIncomingState *mis = migration_incoming_get_current();
+
+    if (mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
+        /* Resumed from a paused postcopy migration */
+
+        mis->from_src_file = f;
+        /* Postcopy has standalone thread to do vm load */
+        qemu_file_set_blocking(f, true);
+
+        /* Re-configure the return path */
+        mis->to_src_file = qemu_file_get_return_path(f);
+
+        migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
+                          MIGRATION_STATUS_POSTCOPY_RECOVER);
+
+        /*
+         * Here, we only wake up the main loading thread (while the
+         * fault thread will still be waiting), so that we can receive
+         * commands from source now, and answer it if needed. The
+         * fault thread will be woken up afterwards until we are sure
+         * that source is ready to reply to page requests.
+         */
+        qemu_sem_post(&mis->postcopy_pause_sem_dst);
+    } else {
+        /* New incoming migration */
+        migration_incoming_setup(f);
+        migration_incoming_process();
+    }
 }
 
 void migration_ioc_process_incoming(QIOChannel *ioc)