fs/ceph:fix double unlock in handle_cap_export()
diff mbox series

Message ID 1588077962-353994-1-git-send-email-wubo40@huawei.com
State New
Headers show
Series
  • fs/ceph:fix double unlock in handle_cap_export()
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Commit Message

Wu Bo April 28, 2020, 12:46 p.m. UTC
If the ceph_mdsc_open_export_target_session() return fails,
should add a lock to avoid twice unlocking.
Because the lock will be released at the retry or out_unlock tag. 

Signed-off-by: Wu Bo <wubo40@huawei.com>
---
 fs/ceph/caps.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

Comments

Yan, Zheng April 28, 2020, 1:41 p.m. UTC | #1
On Tue, Apr 28, 2020 at 8:50 PM Wu Bo <wubo40@huawei.com> wrote:
>
> If the ceph_mdsc_open_export_target_session() return fails,
> should add a lock to avoid twice unlocking.
> Because the lock will be released at the retry or out_unlock tag.
>

at retry label, i_ceph_lock get locked. I don't see how i_ceph_lock
can get double unlock

> Signed-off-by: Wu Bo <wubo40@huawei.com>
> ---
>  fs/ceph/caps.c | 26 ++++++++++++++------------
>  1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 185db76..b5a62a8 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -3731,22 +3731,24 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
>
>         /* open target session */
>         tsession = ceph_mdsc_open_export_target_session(mdsc, target);
> -       if (!IS_ERR(tsession)) {
> -               if (mds > target) {
> -                       mutex_lock(&session->s_mutex);
> -                       mutex_lock_nested(&tsession->s_mutex,
> -                                         SINGLE_DEPTH_NESTING);
> -               } else {
> -                       mutex_lock(&tsession->s_mutex);
> -                       mutex_lock_nested(&session->s_mutex,
> -                                         SINGLE_DEPTH_NESTING);
> -               }
> -               new_cap = ceph_get_cap(mdsc, NULL);
> -       } else {
> +       if (IS_ERR(tsession)) {
>                 WARN_ON(1);
>                 tsession = NULL;
>                 target = -1;
> +               mutex_lock(&session->s_mutex);
> +               goto out_unlock;
> +       }
> +
> +       if (mds > target) {
> +               mutex_lock(&session->s_mutex);
> +               mutex_lock_nested(&tsession->s_mutex,
> +                                       SINGLE_DEPTH_NESTING);
> +       } else {
> +               mutex_lock(&tsession->s_mutex);
> +               mutex_lock_nested(&session->s_mutex,
> +                                       SINGLE_DEPTH_NESTING);
>         }
> +       new_cap = ceph_get_cap(mdsc, NULL);
>         goto retry;
>
>  out_unlock:
> --
> 1.8.3.1
>
Wu Bo April 28, 2020, 1:54 p.m. UTC | #2
On 2020/4/28 21:41, Yan, Zheng wrote:
> On Tue, Apr 28, 2020 at 8:50 PM Wu Bo <wubo40@huawei.com> wrote:
>>
>> If the ceph_mdsc_open_export_target_session() return fails,
>> should add a lock to avoid twice unlocking.
>> Because the lock will be released at the retry or out_unlock tag.
>>
> 
> at retry label, i_ceph_lock get locked. I don't see how i_ceph_lock
> can get double unlock
>sorry, maybe I didn't describe it clearly enough, not i_ceph_lock, but 
session->s_mutex.

Thanks.

Wu Bo
>> Signed-off-by: Wu Bo <wubo40@huawei.com>
>> ---
>>   fs/ceph/caps.c | 26 ++++++++++++++------------
>>   1 file changed, 14 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index 185db76..b5a62a8 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -3731,22 +3731,24 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
>>
>>          /* open target session */
>>          tsession = ceph_mdsc_open_export_target_session(mdsc, target);
>> -       if (!IS_ERR(tsession)) {
>> -               if (mds > target) {
>> -                       mutex_lock(&session->s_mutex);
>> -                       mutex_lock_nested(&tsession->s_mutex,
>> -                                         SINGLE_DEPTH_NESTING);
>> -               } else {
>> -                       mutex_lock(&tsession->s_mutex);
>> -                       mutex_lock_nested(&session->s_mutex,
>> -                                         SINGLE_DEPTH_NESTING);
>> -               }
>> -               new_cap = ceph_get_cap(mdsc, NULL);
>> -       } else {
>> +       if (IS_ERR(tsession)) {
>>                  WARN_ON(1);
>>                  tsession = NULL;
>>                  target = -1;
>> +               mutex_lock(&session->s_mutex);
>> +               goto out_unlock;
>> +       }
>> +
>> +       if (mds > target) {
>> +               mutex_lock(&session->s_mutex);
>> +               mutex_lock_nested(&tsession->s_mutex,
>> +                                       SINGLE_DEPTH_NESTING);
>> +       } else {
>> +               mutex_lock(&tsession->s_mutex);
>> +               mutex_lock_nested(&session->s_mutex,
>> +                                       SINGLE_DEPTH_NESTING);
>>          }
>> +       new_cap = ceph_get_cap(mdsc, NULL);
>>          goto retry;
>>
>>   out_unlock:
>> --
>> 1.8.3.1
>>
> 
> .
>

Patch
diff mbox series

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 185db76..b5a62a8 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3731,22 +3731,24 @@  static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 
 	/* open target session */
 	tsession = ceph_mdsc_open_export_target_session(mdsc, target);
-	if (!IS_ERR(tsession)) {
-		if (mds > target) {
-			mutex_lock(&session->s_mutex);
-			mutex_lock_nested(&tsession->s_mutex,
-					  SINGLE_DEPTH_NESTING);
-		} else {
-			mutex_lock(&tsession->s_mutex);
-			mutex_lock_nested(&session->s_mutex,
-					  SINGLE_DEPTH_NESTING);
-		}
-		new_cap = ceph_get_cap(mdsc, NULL);
-	} else {
+	if (IS_ERR(tsession)) {
 		WARN_ON(1);
 		tsession = NULL;
 		target = -1;
+		mutex_lock(&session->s_mutex);
+		goto out_unlock;
+	}
+
+	if (mds > target) {
+		mutex_lock(&session->s_mutex);
+		mutex_lock_nested(&tsession->s_mutex,
+					SINGLE_DEPTH_NESTING);
+	} else {
+		mutex_lock(&tsession->s_mutex);
+		mutex_lock_nested(&session->s_mutex,
+					SINGLE_DEPTH_NESTING);
 	}
+	new_cap = ceph_get_cap(mdsc, NULL);
 	goto retry;
 
 out_unlock: