Re: [PATCH 4/5] fusion prevent DV deadlock

[Bernd Schubert <bs@q-leap.de>]

On Fri, Sep 12, 2008 at 09:02:16PM +0200, Bernd Schubert wrote:
> The mpt fusion driver will do a domain revalidation on an ion reset, this

s/ion/ioc/

> DV might cause a live deadlock. The problem has been entirely analyzed in
> this thread, but so far no real solution has been implemented.
> This patch simply disables the domain revalidation, if it will run into
> the deadlock.

Forgot to paste the thread: http://marc.info/?t=118039577800004

> 
> Signed-off-by: Bernd Schubert <bs@q-leap.de>
> 
>  drivers/message/fusion/mptspi.c |   12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> 
> Index: linux-2.6.26/drivers/message/fusion/mptspi.c
> ===================================================================
> --- linux-2.6.26.orig/drivers/message/fusion/mptspi.c
> +++ linux-2.6.26/drivers/message/fusion/mptspi.c
> @@ -672,12 +672,24 @@ static void mptspi_dv_device(struct _MPT
>  {
>  	VirtTarget *vtarget = scsi_target(sdev)->hostdata;
>  	MPT_ADAPTER *ioc = hd->ioc;
> +	unsigned long nr_requests = sdev->request_queue->nr_requests;
> +	struct request_list *rl = &sdev->request_queue->rq;
>  
>  	/* no DV on RAID devices */
>  	if (sdev->channel == 0 &&
>  	    mptspi_is_raid(hd, sdev->id))
>  		return;
>  
> +	if (rl->count[0] + 1 >= nr_requests
> +	||  rl->count[1] + 1 >= nr_requests) {
> +		/* we must NOT do a DV after an error recovery, when we
> +		 * don't have left a space in the request list, since
> +		 * this will cause a live dead lock */
> +		starget_printk(KERN_INFO, scsi_target(sdev), MYIOC_s_FMT
> +		    "Skipping DV, to prevent dead lock!\n", ioc->name);
> +		return;
> +	}
> +
>  	/* If this is a piece of a RAID, then quiesce first */
>  	if (sdev->channel == 1 &&
>  	    mptscsih_quiesce_raid(hd, 1, vtarget->channel, vtarget->id) < 0) {
> --
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