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

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Date:	Mon, 15 Sep 2008 16:22:04 -0700
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	Elias Oltmanns <eo@...ensachen.de>
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

On Monday 15 September 2008 12:15:26 Elias Oltmanns wrote:
> 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.

OK.

I've just audited your latest patch and it all seems good (the assumptions
taken are valid and all concerns were addressed) so you may add my ACK to
the next-time-round patch.  Big thanks for patiently improving this patch,
the final version looks so much better than the initial/draft one. :)

Thanks,
Bart
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