linux-kernel - Re: [PATCH 2/4 v2] libata: Implement disk shock protection support

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Date:	Wed, 17 Sep 2008 11:03:39 -0700
From:	Tejun Heo <htejun@...il.com>
To:	Elias Oltmanns <eo@...ensachen.de>
CC:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	Jeff Garzik <jeff@...zik.org>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4 v2] libata: Implement disk shock protection support

Hello, Elias.

Looks generally good.  Just a few points.

Elias Oltmanns wrote:
> +static void ata_eh_pull_action(struct ata_link *link, struct ata_device *dev,
> +			unsigned int action)
> +{
> +	struct ata_port *ap = link->ap;
> +	struct ata_eh_info *ehi = &link->eh_info, *ehci = &link->eh_context.i;
> +	struct ata_device *tdev;
> +	unsigned int taction;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(ap->lock, flags);
> +
> +	if (dev) {
> +		taction = action & (ehi->action | ehi->dev_action[dev->devno]);
> +		ehci->dev_action[dev->devno] |= taction & ATA_EH_PERDEV_MASK;
> +		ehci->action |= taction & ~ATA_EH_PERDEV_MASK;
> +	} else {
> +		if (WARN_ON(action & ATA_EH_PERDEV_MASK))
> +			action &= ~ATA_EH_PERDEV_MASK;
> +		ata_link_for_each_dev(tdev, link)
> +			taction |= ehi->dev_action[tdev->devno] & action;

taction seems to be being used uninitialized.

> +	do {
> +		unsigned long now;
> +
> +		deadline = jiffies;
> +		ata_port_for_each_link(link, ap) {
> +			ata_link_for_each_dev(dev, link) {
> +				struct ata_eh_info *ehi = &link->eh_context.i;
> +
> +				if (dev->class != ATA_DEV_ATA)
> +					continue;
> +
> +				ata_eh_pull_action(link, dev, ATA_EH_PARK);
> +				if (ehi->dev_action[dev->devno] & ATA_EH_PARK) {
> +					unsigned long tmp =
> +						dev->unpark_deadline;
> +
> +					if (time_before(deadline, tmp))
> +						deadline = tmp;
> +					else if (time_before_eq(tmp, jiffies))
> +						continue;
> +				}
> +
> +				ata_eh_park_issue_cmd(dev, 1);
> +			}
> +		}
> +		now = jiffies;
> +		if (time_before_eq(deadline, now))
> +			break;
> +		prepare_to_wait(&ata_scsi_park_wq, &wait, TASK_UNINTERRUPTIBLE);

Doesn't prepare_to_wait() have to come before pull_action and timeout
check?  Which in turn means that it should be a completion instead of
wait combined with INIT_COMPLETION because thread state can't be used
to track wake up as ata_eh_park_issue_cmd() sleeps.

Thanks.  :-)

-- 
tejun
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