migration: split migration_incoming_co
Originally, migration_incoming_co was introduced by
25d0c16f625feb3b6
"migration: Switch to COLO process after finishing loadvm"
to be able to enter from COLO code to one specific yield point, added
by 25d0c16f625feb3b6.
Later in 923709896b1b0
"migration: poll the cm event for destination qemu"
we reused this variable to wake the migration incoming coroutine from
RDMA code.
That was doubtful idea. Entering coroutines is a very fragile thing:
you should be absolutely sure which yield point you are going to enter.
I don't know how much is it safe to enter during qemu_loadvm_state()
which I think what RDMA want to do. But for sure RDMA shouldn't enter
the special COLO-related yield-point. As well, COLO code doesn't want
to enter during qemu_loadvm_state(), it want to enter it's own specific
yield-point.
As well, when in 8e48ac95865ac97d
"COLO: Add block replication into colo process" we added
bdrv_invalidate_cache_all() call (now it's called activate_all())
it became possible to enter the migration incoming coroutine during
that call which is wrong too.
So, let't make these things separate and disjoint: loadvm_co for RDMA,
non-NULL during qemu_loadvm_state(), and colo_incoming_co for COLO,
non-NULL only around specific yield.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20230515130640.46035-3-vsementsov@yandex-team.ru>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/migration/colo.c b/migration/colo.c
index 6c7c313..a688ac5 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -145,8 +145,8 @@
qemu_sem_post(&mis->colo_incoming_sem);
/* For Secondary VM, jump to incoming co */
- if (mis->migration_incoming_co) {
- qemu_coroutine_enter(mis->migration_incoming_co);
+ if (mis->colo_incoming_co) {
+ qemu_coroutine_enter(mis->colo_incoming_co);
}
}
diff --git a/migration/migration.c b/migration/migration.c
index 00d8ba8..a6f2f6c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -520,12 +520,14 @@
goto fail;
}
- mis->migration_incoming_co = qemu_coroutine_self();
mis->largest_page_size = qemu_ram_pagesize_largest();
postcopy_state_set(POSTCOPY_INCOMING_NONE);
migrate_set_state(&mis->state, MIGRATION_STATUS_NONE,
MIGRATION_STATUS_ACTIVE);
+
+ mis->loadvm_co = qemu_coroutine_self();
ret = qemu_loadvm_state(mis->from_src_file);
+ mis->loadvm_co = NULL;
ps = postcopy_state_get();
trace_process_incoming_migration_co_end(ret, ps);
@@ -566,7 +568,10 @@
qemu_thread_create(&colo_incoming_thread, "COLO incoming",
colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE);
+
+ mis->colo_incoming_co = qemu_coroutine_self();
qemu_coroutine_yield();
+ mis->colo_incoming_co = NULL;
qemu_mutex_unlock_iothread();
/* Wait checkpoint incoming thread exit before free resource */
@@ -578,7 +583,6 @@
mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
qemu_bh_schedule(mis->bh);
- mis->migration_incoming_co = NULL;
return;
fail:
local_err = NULL;
diff --git a/migration/migration.h b/migration/migration.h
index 7721c76..48a4612 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -162,8 +162,15 @@
int state;
+ /*
+ * The incoming migration coroutine, non-NULL during qemu_loadvm_state().
+ * Used to wake the migration incoming coroutine from rdma code. How much is
+ * it safe - it's a question.
+ */
+ Coroutine *loadvm_co;
+
/* The coroutine we should enter (back) after failover */
- Coroutine *migration_incoming_co;
+ Coroutine *colo_incoming_co;
QemuSemaphore colo_incoming_sem;
/*
diff --git a/migration/rdma.c b/migration/rdma.c
index 2cd8f1c..2e4dcff 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3342,9 +3342,8 @@
}
}
rdma_ack_cm_event(cm_event);
-
- if (mis->migration_incoming_co) {
- qemu_coroutine_enter(mis->migration_incoming_co);
+ if (mis->loadvm_co) {
+ qemu_coroutine_enter(mis->loadvm_co);
}
return;
}
