* [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock
@ 2010-07-16 15:13 Wengang Wang
2010-07-20 2:31 ` Wengang Wang
2010-08-07 18:39 ` Joel Becker
0 siblings, 2 replies; 4+ messages in thread
From: Wengang Wang @ 2010-07-16 15:13 UTC (permalink / raw)
To: ocfs2-devel
When we have to take both dlm->master_lock and lockres->spinlock,
take them in order
lockres->spinlock and then dlm->master_lock.
The patch fixes a violation of the rule.
We can simply move taking dlm->master_lock to where we have dropped res->spinlock
since when we access res->state and free mle memory we don't need master_lock's
protection.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
---
fs/ocfs2/dlm/dlmmaster.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 94b97fc..6d098b8 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -3050,8 +3050,6 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
/* check for pre-existing lock */
spin_lock(&dlm->spinlock);
res = __dlm_lookup_lockres(dlm, name, namelen, hash);
- spin_lock(&dlm->master_lock);
-
if (res) {
spin_lock(&res->spinlock);
if (res->state & DLM_LOCK_RES_RECOVERING) {
@@ -3069,14 +3067,15 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
spin_unlock(&res->spinlock);
}
+ spin_lock(&dlm->master_lock);
/* ignore status. only nonzero status would BUG. */
ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
name, namelen,
migrate->new_master,
migrate->master);
-unlock:
spin_unlock(&dlm->master_lock);
+unlock:
spin_unlock(&dlm->spinlock);
if (oldmle) {
--
1.6.6.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock
2010-07-16 15:13 [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock Wengang Wang
@ 2010-07-20 2:31 ` Wengang Wang
2010-07-20 22:59 ` Sunil Mushran
2010-08-07 18:39 ` Joel Becker
1 sibling, 1 reply; 4+ messages in thread
From: Wengang Wang @ 2010-07-20 2:31 UTC (permalink / raw)
To: ocfs2-devel
Just a reminder.
wengang.
On 10-07-16 23:13, Wengang Wang wrote:
> When we have to take both dlm->master_lock and lockres->spinlock,
> take them in order
>
> lockres->spinlock and then dlm->master_lock.
>
> The patch fixes a violation of the rule.
> We can simply move taking dlm->master_lock to where we have dropped res->spinlock
> since when we access res->state and free mle memory we don't need master_lock's
> protection.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
> ---
> fs/ocfs2/dlm/dlmmaster.c | 5 ++---
> 1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index 94b97fc..6d098b8 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -3050,8 +3050,6 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
> /* check for pre-existing lock */
> spin_lock(&dlm->spinlock);
> res = __dlm_lookup_lockres(dlm, name, namelen, hash);
> - spin_lock(&dlm->master_lock);
> -
> if (res) {
> spin_lock(&res->spinlock);
> if (res->state & DLM_LOCK_RES_RECOVERING) {
> @@ -3069,14 +3067,15 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
> spin_unlock(&res->spinlock);
> }
>
> + spin_lock(&dlm->master_lock);
> /* ignore status. only nonzero status would BUG. */
> ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
> name, namelen,
> migrate->new_master,
> migrate->master);
>
> -unlock:
> spin_unlock(&dlm->master_lock);
> +unlock:
> spin_unlock(&dlm->spinlock);
>
> if (oldmle) {
> --
> 1.6.6.1
>
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock
2010-07-20 2:31 ` Wengang Wang
@ 2010-07-20 22:59 ` Sunil Mushran
0 siblings, 0 replies; 4+ messages in thread
From: Sunil Mushran @ 2010-07-20 22:59 UTC (permalink / raw)
To: ocfs2-devel
Acked-by: Sunil Mushran <sunil.mushran@oracle.com>
On 07/19/2010 07:31 PM, Wengang Wang wrote:
> Just a reminder.
>
> wengang.
> On 10-07-16 23:13, Wengang Wang wrote:
>
>> When we have to take both dlm->master_lock and lockres->spinlock,
>> take them in order
>>
>> lockres->spinlock and then dlm->master_lock.
>>
>> The patch fixes a violation of the rule.
>> We can simply move taking dlm->master_lock to where we have dropped res->spinlock
>> since when we access res->state and free mle memory we don't need master_lock's
>> protection.
>>
>> Signed-off-by: Wengang Wang<wen.gang.wang@oracle.com>
>> ---
>> fs/ocfs2/dlm/dlmmaster.c | 5 ++---
>> 1 files changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
>> index 94b97fc..6d098b8 100644
>> --- a/fs/ocfs2/dlm/dlmmaster.c
>> +++ b/fs/ocfs2/dlm/dlmmaster.c
>> @@ -3050,8 +3050,6 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
>> /* check for pre-existing lock */
>> spin_lock(&dlm->spinlock);
>> res = __dlm_lookup_lockres(dlm, name, namelen, hash);
>> - spin_lock(&dlm->master_lock);
>> -
>> if (res) {
>> spin_lock(&res->spinlock);
>> if (res->state& DLM_LOCK_RES_RECOVERING) {
>> @@ -3069,14 +3067,15 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
>> spin_unlock(&res->spinlock);
>> }
>>
>> + spin_lock(&dlm->master_lock);
>> /* ignore status. only nonzero status would BUG. */
>> ret = dlm_add_migration_mle(dlm, res, mle,&oldmle,
>> name, namelen,
>> migrate->new_master,
>> migrate->master);
>>
>> -unlock:
>> spin_unlock(&dlm->master_lock);
>> +unlock:
>> spin_unlock(&dlm->spinlock);
>>
>> if (oldmle) {
>> --
>> 1.6.6.1
>>
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
>>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock
2010-07-16 15:13 [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock Wengang Wang
2010-07-20 2:31 ` Wengang Wang
@ 2010-08-07 18:39 ` Joel Becker
1 sibling, 0 replies; 4+ messages in thread
From: Joel Becker @ 2010-08-07 18:39 UTC (permalink / raw)
To: ocfs2-devel
On Fri, Jul 16, 2010 at 11:13:33PM +0800, Wengang Wang wrote:
> When we have to take both dlm->master_lock and lockres->spinlock,
> take them in order
>
> lockres->spinlock and then dlm->master_lock.
>
> The patch fixes a violation of the rule.
> We can simply move taking dlm->master_lock to where we have dropped res->spinlock
> since when we access res->state and free mle memory we don't need master_lock's
> protection.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
This patch is now in the fixes branch of ocfs2.git.
Joel
--
"Three o'clock is always too late or too early for anything you
want to do."
- Jean-Paul Sartre
Joel Becker
Consulting Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-07-16 15:13 [Ocfs2-devel] [PATCH] ocfs2/dlm: fix a dead lock Wengang Wang
2010-07-20 2:31 ` Wengang Wang
2010-07-20 22:59 ` Sunil Mushran
2010-08-07 18:39 ` Joel Becker
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