linux-kernel - Re: [PATCH 3/4] ide: Implement disk shock protection support

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Date:	Mon, 15 Sep 2008 21:15:26 +0200
From:	Elias Oltmanns <eo@...ensachen.de>
To:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Garzik <jeff@...zik.org>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Tejun Heo <htejun@...il.com>, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] ide: Implement disk shock protection support

Elias Oltmanns <eo@...ensachen.de> wrote:
> From: Elias Oltmanns <eo@...ensachen.de>
> Subject: [PATCH] ide: Implement disk shock protection support
>
> On user request (through sysfs), the IDLE IMMEDIATE command with UNLOAD
> FEATURE as specified in ATA-7 is issued to the device and processing of
> the request queue is stopped thereafter until the specified timeout
> expires or user space asks to resume normal operation. This is supposed
> to prevent the heads of a hard drive from accidentally crashing onto the
> platter when a heavy shock is anticipated (like a falling laptop expected
> to hit the floor). Port resets are deferred whenever a device on that
> port is in the parked state.
>
> Signed-off-by: Elias Oltmanns <eo@...ensachen.de>
[...]
> diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c
> new file mode 100644
> index 0000000..8cd43f6
> --- /dev/null
> +++ b/drivers/ide/ide-park.c
> @@ -0,0 +1,119 @@
> +#include <linux/kernel.h>
> +#include <linux/ide.h>
> +#include <linux/jiffies.h>
> +#include <linux/blkdev.h>
> +
> +DECLARE_WAIT_QUEUE_HEAD(ide_park_wq);
> +
> +static int issue_park_cmd(ide_drive_t *drive, unsigned long timeout)
> +{
> +	struct request_queue *q = drive->queue;
> +	struct request *rq;
> +	int rc;
> +
> +	timeout += jiffies;
> +	spin_lock_irq(&ide_lock);
> +	if (drive->dev_flags & IDE_DFLAG_PARKED) {
> +		ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
> +		int reset_timer;
> +
> +		reset_timer = time_before(timeout, drive->sleep);
> +		drive->sleep = timeout;
> +		if (reset_timer) {
> +			wake_up_all(&ide_park_wq);
> +			if (hwgroup->sleeping && del_timer(&hwgroup->timer)) {
> +				hwgroup->sleeping = 0;
> +				hwgroup->busy = 0;
> +				__blk_run_queue(q);
> +			}
> +		}
> +		spin_unlock_irq(&ide_lock);
> +		return 0;
> +	}

This wake_up_all() has to go outside the if clause. I'll change this the
next time round to be called right after drive->sleep has been set. The
two nested if clauses will be unified and the conditions &&'ed.

Regards,

Elias
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