[PATCH v10 4/6] migration/dirtyrate: adjust order of registering thread

[huangy81@chinatelecom.cn]

From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

registering get_dirtyrate thread in advance so that both
page-sampling and dirty-ring mode can be covered.

Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
Message-Id: <d7727581a8e86d4a42fc3eacf7f310419b9ebf7e.1624040308.git.huangy81@chinatelecom.cn>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 migration/dirtyrate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index e0a27a9..a9bdd60 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -352,7 +352,6 @@ static void calculate_dirtyrate(struct DirtyRateConfig config)
     int64_t msec = 0;
     int64_t initial_time;
 
-    rcu_register_thread();
     rcu_read_lock();
     initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
     if (!record_ramblock_hash_info(&block_dinfo, config, &block_count)) {
@@ -375,7 +374,6 @@ static void calculate_dirtyrate(struct DirtyRateConfig config)
 out:
     rcu_read_unlock();
     free_ramblock_dirty_info(block_dinfo, block_count);
-    rcu_unregister_thread();
 }
 
 void *get_dirtyrate_thread(void *arg)
@@ -383,6 +381,7 @@ void *get_dirtyrate_thread(void *arg)
     struct DirtyRateConfig config = *(struct DirtyRateConfig *)arg;
     int ret;
     int64_t start_time;
+    rcu_register_thread();
 
     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_UNSTARTED,
                               DIRTY_RATE_STATUS_MEASURING);
@@ -401,6 +400,8 @@ void *get_dirtyrate_thread(void *arg)
     if (ret == -1) {
         error_report("change dirtyrate state failed.");
     }
+
+    rcu_unregister_thread();
     return NULL;
 }
 
-- 
1.8.3.1