linux-kernel - Re: [PATCH V3] fs/ceph:fix double unlock in handle_cap

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Date:   Thu, 30 Apr 2020 08:08:11 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Wu Bo <wubo40@...wei.com>, ukernel@...il.com, sage@...hat.com,
        idryomov@...il.com
Cc:     ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        liuzhiqiang26@...wei.com, linfeilong@...wei.com
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 <wubo40@...wei.com>
> ---
>  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 <jlayton@...nel.org>