Re: [PATCH v5 04/14] md: don't register sync_thread for reshape directly

[Yu Kuai]

Hi,

在 2024/02/28 20:07, Xiao Ni 写道:
> I have a question here. Is it the reason sync_thread can't run 
> md_do_sync because kthread_should_stop, so it doesn't have the chance to 
> set MD_RECOVERY_DONE? Why creating sync thread in md_check_recovery 
> doesn't have this problem? Could you explain more about this?

raid10_run() only register sync_thread, without calling
md_wakeup_thread() to set the bit 'THREAD_WAKEUP', md_do_sync() will not
be executed.

raid5 defines 'pers->start' hence md_start() will call
md_wakeup_thread().

md_start_sync() will always call md_wakeup_thread() hence there is no
such problem.

BTW, this patch fix the same problem as you mentioned in your other
thread:

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2266358d8074..54790261254d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4904,6 +4904,7 @@ static void stop_sync_thread(struct mddev *mddev, 
bool locked, bool check_seq)
 	 * never happen
 	 */
 	md_wakeup_thread_directly(mddev->sync_thread);
+	md_wakeup_thread(mddev->sync_thread);
 	if (work_pending(&mddev->sync_work))
 		flush_work(&mddev->sync_work);

However, I think the one to register sync_thread is responsible to wake
it up.

Thanks,
Kuai