linux-kernel - Re: [PATCH 9/12] repost: cciss: add busy

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Message-ID: <20061106203200.GG19471@kernel.dk>
Date:	Mon, 6 Nov 2006 21:32:00 +0100
From:	Jens Axboe <jens.axboe@...cle.com>
To:	"Mike Miller (OS Dev)" <mikem@...rdog.cca.cpqcorp.net>
Cc:	akpm@...l.org, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org
Subject: Re: [PATCH 9/12] repost: cciss: add busy_configuring flag

On Mon, Nov 06 2006, Mike Miller (OS Dev) wrote:
> PATCH 9 of 12
> 
> This patch adds a check for busy_configuring to prevent starting a queue
> on a drive that may be in the midst of updating, configuring, deleting, etc.
> 
> This had a test for if the queue was stopped or plugged but that seemed
> to cause issues.
> Please consider this for inclusion.
> 
> Thanks,
> mikem
> 
> Signed-off-by: Mike Miller <mike.miller@...com>
> 
> --------------------------------------------------------------------------------
> 
> ---
> 
>  drivers/block/cciss.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff -puN drivers/block/cciss.c~cciss_busy_conf_for_lx2619-rc4 drivers/block/cciss.c
> --- linux-2.6/drivers/block/cciss.c~cciss_busy_conf_for_lx2619-rc4	2006-11-06 13:27:53.000000000 -0600
> +++ linux-2.6-root/drivers/block/cciss.c	2006-11-06 13:27:53.000000000 -0600
> @@ -1190,8 +1190,11 @@ static void cciss_check_queues(ctlr_info
>  		/* make sure the disk has been added and the drive is real
>  		 * because this can be called from the middle of init_one.
>  		 */
> -		if (!(h->drv[curr_queue].queue) || !(h->drv[curr_queue].heads))
> +		if (!(h->drv[curr_queue].queue) ||
> +		    !(h->drv[curr_queue].heads) ||
> +		    h->drv[curr_queue].busy_configuring)
>  			continue;
> +
>  		blk_start_queue(h->gendisk[curr_queue]->queue);

This is racy, because you don't start the queue when you unset
->busy_configuring later on. For this to be safe, you need to call
blk_start_queue() when you set ->busy_configuring to 0.

-- 
Jens Axboe

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