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List:       dm-devel
Subject:    Re: [dm-devel] [PATCH 3/6] scsi_dh : release the refcounts in
From:       James Bottomley <James.Bottomley () suse ! de>
Date:       2010-07-30 0:12:07
Message-ID: 1280448727.4441.942.camel () mulgrave ! site
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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


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