linux-kernel - Re: [PATCH v4 1/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target

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Date:	Wed, 13 Apr 2016 10:19:48 +0200
From:	Johannes Thumshirn <jthumshirn@...e.de>
To:	Xiong Zhou <jencce.kernel@...il.com>
Cc:	"Martin K. Petersen" <martin.petersen@...cle.com>,
	"James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
	"Ewan D. Milne" <emilne@...hat.com>,
	Hannes Reinecke <hare@...e.de>,
	Christoph Hellwig <hch@...radead.org>,
	linux-scsi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH v4 1/2] scsi: Add intermediate STARGET_REMOVE state to scsi_target_state

Hi Xiong
Sorry for the late reply

On Dienstag, 12. April 2016 21:01:53 CEST Xiong Zhou wrote:
> How about this?
> 
> drivers/scsi/scsi_scan: mark STARGET_REMOVE state before destroy
> 
> Signed-off-by: Xiong Zhou <jencce.kernel@...il.com>
> ---
>  drivers/scsi/scsi_scan.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 27df7e7..21092e5 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -395,6 +395,8 @@ static void scsi_target_reap_ref_release(struct kref *kref)
>   transport_remove_device(&starget->dev);
>   device_del(&starget->dev);
>   }
> +
> + starget->state = STARGET_REMOVE;
>   scsi_target_destroy(starget);
>  }

The only scsi_target_reap_ref_release() caller is scsi_target_reap_ref_put(), 
which in turn is only called by scsi_target_reap(). scsi_target_reap()'s only 
callers are scsi_remove_target()/__scsi_remove_target(), which set the 
STARGET_REMOVE state and 

__scsi_add_device()
scsi_get_host_dev()
__scsi_scan_target()

Which I'm currently investiganting (in parallel to reproducing the bug).

> 
> @@ -465,6 +467,7 @@ static struct scsi_target
> *scsi_alloc_target(struct device *parent,
>   dev_printk(KERN_ERR, dev, "target allocation failed, error %d\n", error);
>   /* don't want scsi_target_reap to do the final
>   * put because it will be under the host lock */
> + starget->state = STARGET_REMOVE;
>   scsi_target_destroy(starget);
>   return NULL;
>   }

Here starget->state is STARGET_CREATED and the assertion is already aware of 
this state transitoin. IOTW this /shouldn't/ be needed.


-- 
Johannes Thumshirn                                                                                Storage
jthumshirn@...e.de                                                             +49 911 74053 689
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