linux-kernel - Re: [Xen-devel] [PATCH 3/3] xen/blkback: Check for insane amounts of request on the ring.

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Date:	Mon, 28 Jan 2013 11:38:50 +0000
From:	David Vrabel <david.vrabel@...rix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xensource.com>,
	Konrad Rzeszutek Wilk <konrad@...nel.org>,
	<stable@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 3/3] xen/blkback: Check for insane amounts
 of request on the ring.

On 25/01/13 18:43, Konrad Rzeszutek Wilk wrote:
> 
> Check that the ring does not have an insane amount of requests
> (more than there could fit on the ring).
[...]
> --- a/drivers/block/xen-blkback/blkback.c
> +++ b/drivers/block/xen-blkback/blkback.c
[...]
> @@ -415,8 +415,12 @@ int xen_blkif_schedule(void *arg)
>  		blkif->waiting_reqs = 0;
>  		smp_mb(); /* clear flag *before* checking for work */
>  
> -		if (do_block_io_op(blkif))
> +		rc = do_block_io_op(blkif);
> +		if (rc > 0)
>  			blkif->waiting_reqs = 1;
> +		if (rc == -EACCES)
> +			wait_event_interruptible(blkif->shutdown_wq,
> +						 kthread_should_stop());

So if this happens then the backend silently stops processing any
further requests?  I think it should print an error and disconnect from
the front end.

David
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