在 2023/6/13 下午8:44, Yu Kuai 写道:
Hi,
在 2023/06/13 20:25, Xiao Ni 写道:
On Tue, Jun 13, 2023 at 8:00 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
Hi,
在 2023/06/13 16:02, Xiao Ni 写道:
在 2023/5/29 下午9:20, Yu Kuai 写道:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
Prepare to handle 'idle' and 'frozen' differently to fix a deadlock,
there
are no functional changes except that MD_RECOVERY_RUNNING is checked
again after 'reconfig_mutex' is held.
Can you explain more about why it needs to check MD_RECOVERY_RUNNING
again here?
As I explain in the following comment:
Hi
Who can clear the flag before the lock is held?
Basically every where that can clear the flag...
// This context // Other context
mutex_lock
...
test_bit -> pass
clear_bit
mutex_unlock
mutex_lock
test_bit -> check again
Thanks,
Kuai
At first, I wanted to figure out a specific case. Now I have the answer.
Maybe there are two people that want to stop
the sync action at the same time. So this is the case that can be
checked by the codes.
Regards
Xiao
Regards
Xiao
+ /*
+ * Check again in case MD_RECOVERY_RUNNING is cleared before
lock is
+ * held.
+ */
+ if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+ mddev_unlock(mddev);
+ return;
+ }
Thanks,
Kuai
.
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