2020-04-30 06:17:52

by Wu Bo

Subject: [PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

If the ceph_mdsc_open_export_target_session() return fails,
we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block
to avoid twice unlocking. because the session->s_mutex will be unlock
at the out_unlock lable.

--
v2 -> v3:
- Rewrite solution, adding a mutex_lock(&session->s_mutex)
to the IS_ERR(tsession) block.
- Modify the comment more clearly.
v1 -> v2:
- add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable


Signed-off-by: Wu Bo <[email protected]>
---
fs/ceph/caps.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 185db76..d27d778 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
WARN_ON(1);
tsession = NULL;
target = -1;
+ mutex_lock(&session->s_mutex);
}
goto retry;

--
1.8.3.1

2020-04-30 07:59:59

by Yan, Zheng

Subject: Re: [PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

On Thu, Apr 30, 2020 at 2:13 PM Wu Bo <[email protected]> wrote:
>
> If the ceph_mdsc_open_export_target_session() return fails,
> we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block
> to avoid twice unlocking. because the session->s_mutex will be unlock
> at the out_unlock lable.
>
> --
> v2 -> v3:
> - Rewrite solution, adding a mutex_lock(&session->s_mutex)
> to the IS_ERR(tsession) block.
> - Modify the comment more clearly.
> v1 -> v2:
> - add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable
>
>
> Signed-off-by: Wu Bo <[email protected]>
> ---
> fs/ceph/caps.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 185db76..d27d778 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
> WARN_ON(1);
> tsession = NULL;
> target = -1;
> + mutex_lock(&session->s_mutex);
> }
> goto retry;
>
> --
> 1.8.3.1
>

Reviewed-by: "Yan, Zheng" <[email protected]>

2020-04-30 12:10:08

by Jeffrey Layton

Subject: Re: [PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

On Thu, 2020-04-30 at 14:12 +0800, Wu Bo wrote:
> If the ceph_mdsc_open_export_target_session() return fails,
> we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block
> to avoid twice unlocking. because the session->s_mutex will be unlock
> at the out_unlock lable.
>
> --
> v2 -> v3:
> - Rewrite solution, adding a mutex_lock(&session->s_mutex)
> to the IS_ERR(tsession) block.
> - Modify the comment more clearly.
> v1 -> v2:
> - add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable
>

For future reference, notes like this should go a little lower...

>
>
> Signed-off-by: Wu Bo <[email protected]>
> ---
> fs/ceph/caps.c | 1 +
> 1 file changed, 1 insertion(+)
>

If you put the patch version notes here, they'll be stripped out when we
go to merge the patch with git-am.

> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 185db76..d27d778 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
> WARN_ON(1);
> tsession = NULL;
> target = -1;
> + mutex_lock(&session->s_mutex);
> }
> goto retry;
>

Looks good. Merged, but I did clean up the verbiage in the changelog a
bit.

Thanks!
--
Jeff Layton <[email protected]>