[PATCH v3 02/10] migration: Introduce migrate_has_error()

[Peter Xu <peterx@redhat.com>]

Introduce a helper to detect whether MigrationState.error is set for
whatever reason.

This is preparation work for any thread (e.g. source return path thread) to
setup errors in an unified way to MigrationState, rather than relying on
its own way to set errors (mark_source_rp_bad()).

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.h | 1 +
 migration/migration.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/migration/migration.h b/migration/migration.h
index 972597f4de..4106a1dc54 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -476,6 +476,7 @@ bool  migration_has_all_channels(void);
 uint64_t migrate_max_downtime(void);
 
 void migrate_set_error(MigrationState *s, const Error *error);
+bool migrate_has_error(MigrationState *s);
 
 void migrate_fd_connect(MigrationState *s, Error *error_in);
 
diff --git a/migration/migration.c b/migration/migration.c
index 010056d6f3..4c6de8c2dd 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1231,6 +1231,13 @@ void migrate_set_error(MigrationState *s, const Error *error)
     }
 }
 
+bool migrate_has_error(MigrationState *s)
+{
+    /* The lock is not helpful here, but still follow the rule */
+    QEMU_LOCK_GUARD(&s->error_mutex);
+    return qatomic_read(&s->error);
+}
+
 static void migrate_error_free(MigrationState *s)
 {
     QEMU_LOCK_GUARD(&s->error_mutex);
-- 
2.41.0