* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
@ 2019-09-30 3:17 Shuning Zhang
2019-10-07 22:11 ` Andrew Morton
0 siblings, 1 reply; 6+ messages in thread
From: Shuning Zhang @ 2019-09-30 3:17 UTC (permalink / raw)
To: ocfs2-devel
There is a potential task of deadlock. Because the mask
is 0, the deadlock does not occur now. But There is a
potential task. If someone change the mask of mlog, but
forget to modify the order of the mlog and spin_unlock,
There will be a potential deadlock.So I move the mlog
from the spinlock to outsize.
Signed-off-by: Shuning Zhang <sunny.s.zhang@oracle.com>
---
fs/ocfs2/dlmglue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 1420723..9960e61 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
spin_lock(&oi->ip_lock);
if (oi->ip_flags & OCFS2_INODE_DELETED) {
+ spin_unlock(&oi->ip_lock);
mlog(0, "Orphaned inode %llu was deleted while we "
"were waiting on a lock. ip_flags = 0x%x\n",
(unsigned long long)oi->ip_blkno, oi->ip_flags);
- spin_unlock(&oi->ip_lock);
status = -ENOENT;
goto bail;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
2019-09-30 3:17 [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside Shuning Zhang
@ 2019-10-07 22:11 ` Andrew Morton
2019-10-08 1:14 ` Joseph Qi
0 siblings, 1 reply; 6+ messages in thread
From: Andrew Morton @ 2019-10-07 22:11 UTC (permalink / raw)
To: ocfs2-devel
On Mon, 30 Sep 2019 11:17:39 +0800 Shuning Zhang <sunny.s.zhang@oracle.com> wrote:
> There is a potential task of deadlock. Because the mask
> is 0, the deadlock does not occur now. But There is a
> potential task. If someone change the mask of mlog, but
> forget to modify the order of the mlog and spin_unlock,
> There will be a potential deadlock.So I move the mlog
> from the spinlock to outsize.
>
> ...
>
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
>
> spin_lock(&oi->ip_lock);
> if (oi->ip_flags & OCFS2_INODE_DELETED) {
> + spin_unlock(&oi->ip_lock);
> mlog(0, "Orphaned inode %llu was deleted while we "
> "were waiting on a lock. ip_flags = 0x%x\n",
> (unsigned long long)oi->ip_blkno, oi->ip_flags);
> - spin_unlock(&oi->ip_lock);
> status = -ENOENT;
> goto bail;
> }
The patch is obviously OK but I don't see any deadlock. mlog() doesn't
take any locks?
^ permalink raw reply [flat|nested] 6+ messages in thread* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
2019-10-07 22:11 ` Andrew Morton
@ 2019-10-08 1:14 ` Joseph Qi
2019-10-08 5:00 ` sunnyZhang
0 siblings, 1 reply; 6+ messages in thread
From: Joseph Qi @ 2019-10-08 1:14 UTC (permalink / raw)
To: ocfs2-devel
On 19/10/8 06:11, Andrew Morton wrote:
> On Mon, 30 Sep 2019 11:17:39 +0800 Shuning Zhang <sunny.s.zhang@oracle.com> wrote:
>
>> There is a potential task of deadlock. Because the mask
>> is 0, the deadlock does not occur now. But There is a
>> potential task. If someone change the mask of mlog, but
>> forget to modify the order of the mlog and spin_unlock,
>> There will be a potential deadlock.So I move the mlog
>> from the spinlock to outsize.
>>
>> ...
>>
>> --- a/fs/ocfs2/dlmglue.c
>> +++ b/fs/ocfs2/dlmglue.c
>> @@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
>>
>> spin_lock(&oi->ip_lock);
>> if (oi->ip_flags & OCFS2_INODE_DELETED) {
>> + spin_unlock(&oi->ip_lock);
>> mlog(0, "Orphaned inode %llu was deleted while we "
>> "were waiting on a lock. ip_flags = 0x%x\n",
>> (unsigned long long)oi->ip_blkno, oi->ip_flags);
>> - spin_unlock(&oi->ip_lock);
>> status = -ENOENT;
>> goto bail;
>> }
>
> The patch is obviously OK but I don't see any deadlock. mlog() doesn't
> take any locks?
>
I guess Shuning refers the calling of printk with spin lock.
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
^ permalink raw reply [flat|nested] 6+ messages in thread* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
2019-10-08 1:14 ` Joseph Qi
@ 2019-10-08 5:00 ` sunnyZhang
2019-10-08 9:51 ` Joseph Qi
0 siblings, 1 reply; 6+ messages in thread
From: sunnyZhang @ 2019-10-08 5:00 UTC (permalink / raw)
To: ocfs2-devel
? 2019/10/8 ??9:14, Joseph Qi ??:
>
> On 19/10/8 06:11, Andrew Morton wrote:
>> On Mon, 30 Sep 2019 11:17:39 +0800 Shuning Zhang <sunny.s.zhang@oracle.com> wrote:
>>
>>> There is a potential task of deadlock. Because the mask
>>> is 0, the deadlock does not occur now. But There is a
>>> potential task. If someone change the mask of mlog, but
>>> forget to modify the order of the mlog and spin_unlock,
>>> There will be a potential deadlock.So I move the mlog
>>> from the spinlock to outsize.
>>>
>>> ...
>>>
>>> --- a/fs/ocfs2/dlmglue.c
>>> +++ b/fs/ocfs2/dlmglue.c
>>> @@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
>>>
>>> spin_lock(&oi->ip_lock);
>>> if (oi->ip_flags & OCFS2_INODE_DELETED) {
>>> + spin_unlock(&oi->ip_lock);
>>> mlog(0, "Orphaned inode %llu was deleted while we "
>>> "were waiting on a lock. ip_flags = 0x%x\n",
>>> (unsigned long long)oi->ip_blkno, oi->ip_flags);
>>> - spin_unlock(&oi->ip_lock);
>>> status = -ENOENT;
>>> goto bail;
>>> }
>> The patch is obviously OK but I don't see any deadlock. mlog() doesn't
>> take any locks?
>>
> I guess Shuning refers the calling of printk with spin lock.
Yes, It is the calling of printk.
Sorry for the description is not clear enough. :)
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>>
^ permalink raw reply [flat|nested] 6+ messages in thread* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
2019-10-08 5:00 ` sunnyZhang
@ 2019-10-08 9:51 ` Joseph Qi
2019-10-09 7:39 ` sunnyZhang
0 siblings, 1 reply; 6+ messages in thread
From: Joseph Qi @ 2019-10-08 9:51 UTC (permalink / raw)
To: ocfs2-devel
On 19/10/8 13:00, sunnyZhang wrote:
>
> ? 2019/10/8 ??9:14, Joseph Qi ??:
>>
>> On 19/10/8 06:11, Andrew Morton wrote:
>>> On Mon, 30 Sep 2019 11:17:39 +0800 Shuning Zhang <sunny.s.zhang@oracle.com> wrote:
>>>
>>>> There is a potential task of deadlock. Because the mask
>>>> is 0, the deadlock does not occur now. But There is a
>>>> potential task. If someone change the mask of mlog, but
>>>> forget to modify the order of the mlog and spin_unlock,
>>>> There will be a potential deadlock.So I move the mlog
>>>> from the spinlock to outsize.
>>>>
>>>> ...
>>>>
>>>> --- a/fs/ocfs2/dlmglue.c
>>>> +++ b/fs/ocfs2/dlmglue.c
>>>> @@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
>>>> ? ????? spin_lock(&oi->ip_lock);
>>>> ????? if (oi->ip_flags & OCFS2_INODE_DELETED) {
>>>> +??????? spin_unlock(&oi->ip_lock);
>>>> ????????? mlog(0, "Orphaned inode %llu was deleted while we "
>>>> ?????????????? "were waiting on a lock. ip_flags = 0x%x\n",
>>>> ?????????????? (unsigned long long)oi->ip_blkno, oi->ip_flags);
>>>> -??????? spin_unlock(&oi->ip_lock);
>>>> ????????? status = -ENOENT;
>>>> ????????? goto bail;
>>>> ????? }
>>> The patch is obviously OK but I don't see any deadlock.? mlog() doesn't
>>> take any locks?
>>>
>> I guess Shuning refers the calling of printk with spin lock.
>
> Yes, It is the calling of printk.
>
> Sorry for the description is not clear enough. :)
>
IIUC, we can call printk with spinlock, no deadlock will happen.
So I have the same question, where is the "potential deadlock"?
Thanks,
Joseph
^ permalink raw reply [flat|nested] 6+ messages in thread* [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside
2019-10-08 9:51 ` Joseph Qi
@ 2019-10-09 7:39 ` sunnyZhang
0 siblings, 0 replies; 6+ messages in thread
From: sunnyZhang @ 2019-10-09 7:39 UTC (permalink / raw)
To: ocfs2-devel
? 2019/10/8 ??5:51, Joseph Qi ??:
>
> On 19/10/8 13:00, sunnyZhang wrote:
>> ? 2019/10/8 ??9:14, Joseph Qi ??:
>>> On 19/10/8 06:11, Andrew Morton wrote:
>>>> On Mon, 30 Sep 2019 11:17:39 +0800 Shuning Zhang <sunny.s.zhang@oracle.com> wrote:
>>>>
>>>>> There is a potential task of deadlock. Because the mask
>>>>> is 0, the deadlock does not occur now. But There is a
>>>>> potential task. If someone change the mask of mlog, but
>>>>> forget to modify the order of the mlog and spin_unlock,
>>>>> There will be a potential deadlock.So I move the mlog
>>>>> from the spinlock to outsize.
>>>>>
>>>>> ...
>>>>>
>>>>> --- a/fs/ocfs2/dlmglue.c
>>>>> +++ b/fs/ocfs2/dlmglue.c
>>>>> @@ -2315,10 +2315,10 @@ static int ocfs2_inode_lock_update(struct inode *inode,
>>>>> ? ????? spin_lock(&oi->ip_lock);
>>>>> ????? if (oi->ip_flags & OCFS2_INODE_DELETED) {
>>>>> +??????? spin_unlock(&oi->ip_lock);
>>>>> ????????? mlog(0, "Orphaned inode %llu was deleted while we "
>>>>> ?????????????? "were waiting on a lock. ip_flags = 0x%x\n",
>>>>> ?????????????? (unsigned long long)oi->ip_blkno, oi->ip_flags);
>>>>> -??????? spin_unlock(&oi->ip_lock);
>>>>> ????????? status = -ENOENT;
>>>>> ????????? goto bail;
>>>>> ????? }
>>>> The patch is obviously OK but I don't see any deadlock.? mlog() doesn't
>>>> take any locks?
>>>>
>>> I guess Shuning refers the calling of printk with spin lock.
>> Yes, It is the calling of printk.
>>
>> Sorry for the description is not clear enough. :)
>>
> IIUC, we can call printk with spinlock, no deadlock will happen.
> So I have the same question, where is the "potential deadlock"?
I apology for my stupidity.
I have always had a wrong memory, I think printk() can sleep.
@Andrew Please can you help me to withdraw this patch?
Thanks
> Thanks,
> Joseph
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-10-09 7:39 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-30 3:17 [Ocfs2-devel] [PATCH] ocfs2: move the mlog from the spinlock to outside Shuning Zhang
2019-10-07 22:11 ` Andrew Morton
2019-10-08 1:14 ` Joseph Qi
2019-10-08 5:00 ` sunnyZhang
2019-10-08 9:51 ` Joseph Qi
2019-10-09 7:39 ` sunnyZhang
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