[Ocfs2-devel] [patch 1/2] ocfs2/dlm: protect 'tracking_list' by 'track_lock'

[piaojun <piaojun@huawei.com>]

On 2017/9/25 18:35, Joseph Qi wrote:
> 
> 
> On 17/9/23 11:39, piaojun wrote:
>> 'dlm->tracking_list' need to be protected by 'dlm->track_lock'.
>>
>> Signed-off-by: Jun Piao <piaojun@huawei.com>
>> Reviewed-by: Alex Chen <alex.chen@huawei.com>
>> ---
>>  fs/ocfs2/dlm/dlmdomain.c | 7 ++++++-
>>  fs/ocfs2/dlm/dlmmaster.c | 4 ++--
>>  2 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
>> index a2b19fb..b118525 100644
>> --- a/fs/ocfs2/dlm/dlmdomain.c
>> +++ b/fs/ocfs2/dlm/dlmdomain.c
>> @@ -726,12 +726,17 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
>>  		}
>>
>>  		/* This list should be empty. If not, print remaining lockres */
>> +		spin_lock(&dlm->track_lock);
>>  		if (!list_empty(&dlm->tracking_list)) {
>>  			mlog(ML_ERROR, "Following lockres' are still on the "
>>  			     "tracking list:\n");
>> -			list_for_each_entry(res, &dlm->tracking_list, tracking)
>> +			list_for_each_entry(res, &dlm->tracking_list, tracking) {
>> +				spin_unlock(&dlm->track_lock);
> 
> Um... If we unlock here, the iterator still has chance to be corrupted.
> 
> Thanks,
> Joseph
> 

we don't need care much about the corrupted 'tracking_list' because we
have already picked up 'res' from 'tracking_list'. then we will get
'track_lock' again to prevent 'tracking_list' from being corrupted. but
I'd better make sure that 'res' is not NULL before printing, just like:

list_for_each_entry(res, &dlm->tracking_list, tracking) {
		spin_unlock(&dlm->track_lock);
		if (res)
			dlm_print_one_lock_resource(res);
		spin_lock(&dlm->track_lock);
}

Thanks
Jun

>>  				dlm_print_one_lock_resource(res);
>> +				spin_lock(&dlm->track_lock);
>> +			}
>>  		}
>> +		spin_unlock(&dlm->track_lock);
>>
>>  		dlm_mark_domain_leaving(dlm);
>>  		dlm_leave_domain(dlm);
>> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
>> index 3e04279..44e7d18 100644
>> --- a/fs/ocfs2/dlm/dlmmaster.c
>> +++ b/fs/ocfs2/dlm/dlmmaster.c
>> @@ -589,9 +589,9 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
>>
>>  	res->last_used = 0;
>>
>> -	spin_lock(&dlm->spinlock);
>> +	spin_lock(&dlm->track_lock);
>>  	list_add_tail(&res->tracking, &dlm->tracking_list);
>> -	spin_unlock(&dlm->spinlock);
>> +	spin_unlock(&dlm->track_lock);
>>
>>  	memset(res->lvb, 0, DLM_LVB_LEN);
>>  	memset(res->refmap, 0, sizeof(res->refmap));
>>
> .
>