On Fri,  8 Oct 2010 22:37:28 +0900, Jiro SEKIBA wrote:
> insert sparse annotations to fix following sparse warning.
> 
> fs/nilfs2/segment.c:2681:3: warning: context imbalance in 
> 'nilfs_segctor_kill_thread' - unexpected unlock
> 
> Signed-off-by: Jiro SEKIBA <[email protected]>
> ---
>  fs/nilfs2/segment.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
> index 172ad42..c64f6e4 100644
> --- a/fs/nilfs2/segment.c
> +++ b/fs/nilfs2/segment.c
> @@ -2677,12 +2677,23 @@ static void nilfs_segctor_kill_thread(struct 
> nilfs_sc_info *sci)
>  {
>       sci->sc_state |= NILFS_SEGCTOR_QUIT;
>  
> +     /* 
> +      * nilfs_segctor_kill_thread is only called inside sc_state_lock lock.
> +      * sparse doesn't detect the context and warn "unexpected unlock".
> +      * This pretends to lock the sc_state_lock for sparse.
> +      */
> +     __acquire(&sci->sc_state_lock);
>       while (sci->sc_task) {
>               wake_up(&sci->sc_wait_daemon);
>               spin_unlock(&sci->sc_state_lock);
>               wait_event(sci->sc_wait_task, sci->sc_task == NULL);
>               spin_lock(&sci->sc_state_lock);
>       }
> +     /*
> +      * Pretending to lock sc_state_lock will cause "wrong count" warning.
> +      * This pretends to unlock th sc_state_lock for sparse.
> +      */
> +     __release(&sci->sc_state_lock);
>  }
>  
>  /*
> -- 
> 1.5.6.5

Thanks, but you don't have to insert __acquire() and __release() calls
in the function.  Just declare __releases() and __acquires() as below.

 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
+       __releases(&sci->sc_state_lock)
+       __acquires(&sci->sc_state_lock)
 {

You can find this style of examples in other sites in the kernel.

Thanks,
Ryusuke Konishi
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