Re: [dm-devel] [PATCH 3/6] scsi_dh : release the refcounts in scsi_dh_alua handler when activate is complete

[James Bottomley <James Bottomley suse de>]

On Wed, 2010-07-28 at 16:59 -0600, Moger, Babu wrote:
> This patch releases the refcounts when activate is complete in alua handler.
> 
> Signed-off-by: Babu Moger <babu moger lsi com>
> ---
> --- linux-2.6.35-rc5/drivers/scsi/device_handler/scsi_dh_alua.c.orig	2010-07-23 05:58:39.000000000 -0500
> +++ linux-2.6.35-rc5/drivers/scsi/device_handler/scsi_dh_alua.c	2010-07-23 06:00:54.000000000 -0500
> @@ -287,6 +287,8 @@ done:
>  		h->callback_fn(h->callback_data, err);
>  		h->callback_fn = h->callback_data = NULL;
>  	}
> +	kref_put(&h->sdev->scsi_dh_data->kref, scsi_dh_handler_cleanup);
> +	put_device(&h->sdev->sdev_gendev);
>  	return;
>  }
>  
> @@ -684,6 +686,8 @@ static int alua_activate(struct scsi_dev
>  out:
>  	if (fn)
>  		fn(data, err);
> +	kref_put(&sdev->scsi_dh_data->kref, scsi_dh_handler_cleanup);
> +	put_device(&sdev->sdev_gendev);

This sequence is asking for trouble: having to remember to release two
separate references at once.

Logically what should happen is that the reference seems to be on
scsi_dh_data->sdev, so it should be taken when that's initialised and
put in scsi_dh_handler_cleanup ... so no-one has to worry about
forgetting it.

James