libata-eh.c

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	}

	/* Determine which reset to use and record in ehc->i.action.
	 * prereset() may examine and modify it.
	 */
	if (softreset && (!hardreset || (!(lflags & ATA_LFLAG_NO_SRST) &&
					 !sata_set_spd_needed(link) &&
					 !(ehc->i.action & ATA_EH_HARDRESET))))
		tmp_action = ATA_EH_SOFTRESET;
	else
		tmp_action = ATA_EH_HARDRESET;

	ehc->i.action = (ehc->i.action & ~ATA_EH_RESET_MASK) | tmp_action;

	if (prereset) {
		rc = prereset(link, jiffies + ATA_EH_PRERESET_TIMEOUT);
		if (rc) {
			if (rc == -ENOENT) {
				ata_link_printk(link, KERN_DEBUG,
						"port disabled. ignoring.\n");
				ehc->i.action &= ~ATA_EH_RESET_MASK;

				ata_link_for_each_dev(dev, link)
					classes[dev->devno] = ATA_DEV_NONE;

				rc = 0;
			} else
				ata_link_printk(link, KERN_ERR,
					"prereset failed (errno=%d)\n", rc);
			goto out;
		}
	}

	/* prereset() might have modified ehc->i.action */
	if (ehc->i.action & ATA_EH_HARDRESET)
		reset = hardreset;
	else if (ehc->i.action & ATA_EH_SOFTRESET)
		reset = softreset;
	else {
		/* prereset told us not to reset, bang classes and return */
		ata_link_for_each_dev(dev, link)
			classes[dev->devno] = ATA_DEV_NONE;
		rc = 0;
		goto out;
	}

	/* did prereset() screw up?  if so, fix up to avoid oopsing */
	if (!reset) {
		if (softreset)
			reset = softreset;
		else
			reset = hardreset;
	}

 retry:
	deadline = jiffies + ata_eh_reset_timeouts[try++];

	/* shut up during boot probing */
	if (verbose)
		ata_link_printk(link, KERN_INFO, "%s resetting link\n",
				reset == softreset ? "soft" : "hard");

	/* mark that this EH session started with reset */
	if (reset == hardreset)
		ehc->i.flags |= ATA_EHI_DID_HARDRESET;
	else
		ehc->i.flags |= ATA_EHI_DID_SOFTRESET;

	rc = ata_do_reset(link, reset, classes, deadline);

	if (reset == hardreset &&
	    ata_eh_followup_srst_needed(link, rc, classify, classes)) {
		/* okay, let's do follow-up softreset */
		reset = softreset;

		if (!reset) {
			ata_link_printk(link, KERN_ERR,
					"follow-up softreset required "
					"but no softreset avaliable\n");
			rc = -EINVAL;
			goto fail;
		}

		ata_eh_about_to_do(link, NULL, ATA_EH_RESET_MASK);
		rc = ata_do_reset(link, reset, classes, deadline);
	}

	/* -EAGAIN can happen if we skipped followup SRST */
	if (rc && rc != -EAGAIN)
		goto fail;

	/* was classification successful? */
	if (classify && classes[0] == ATA_DEV_UNKNOWN &&
	    !(lflags & ATA_LFLAG_ASSUME_CLASS)) {
		if (try < max_tries) {
			ata_link_printk(link, KERN_WARNING,
					"classification failed\n");
			rc = -EINVAL;
			goto fail;
		}

		ata_link_printk(link, KERN_WARNING,
				"classfication failed, assuming ATA\n");
		lflags |= ATA_LFLAG_ASSUME_ATA;
	}

	ata_link_for_each_dev(dev, link) {
		/* After the reset, the device state is PIO 0 and the
		 * controller state is undefined.  Reset also wakes up
		 * drives from sleeping mode.
		 */
		dev->pio_mode = XFER_PIO_0;
		dev->flags &= ~ATA_DFLAG_SLEEPING;

		if (ata_link_offline(link))
			continue;

		/* apply class override */
		if (lflags & ATA_LFLAG_ASSUME_ATA)
			classes[dev->devno] = ATA_DEV_ATA;
		else if (lflags & ATA_LFLAG_ASSUME_SEMB)
			classes[dev->devno] = ATA_DEV_SEMB_UNSUP; /* not yet */
	}

	/* record current link speed */
	if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
		link->sata_spd = (sstatus >> 4) & 0xf;

	if (postreset)
		postreset(link, classes);

	/* reset successful, schedule revalidation */
	ata_eh_done(link, NULL, ehc->i.action & ATA_EH_RESET_MASK);
	ehc->i.action |= ATA_EH_REVALIDATE;

	rc = 0;
 out:
	/* clear hotplug flag */
	ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;

	spin_lock_irqsave(ap->lock, flags);
	ap->pflags &= ~ATA_PFLAG_RESETTING;
	spin_unlock_irqrestore(ap->lock, flags);

	return rc;

 fail:
	if (rc == -ERESTART || try >= max_tries)
		goto out;

	now = jiffies;
	if (time_before(now, deadline)) {
		unsigned long delta = deadline - now;

		ata_link_printk(link, KERN_WARNING, "reset failed "
				"(errno=%d), retrying in %u secs\n",
				rc, (jiffies_to_msecs(delta) + 999) / 1000);

		while (delta)
			delta = schedule_timeout_uninterruptible(delta);
	}

	if (rc == -EPIPE || try == max_tries - 1)
		sata_down_spd_limit(link);
	if (hardreset)
		reset = hardreset;
	goto retry;
}

static int ata_eh_revalidate_and_attach(struct ata_link *link,
					struct ata_device **r_failed_dev)
{
	struct ata_port *ap = link->ap;
	struct ata_eh_context *ehc = &link->eh_context;
	struct ata_device *dev;
	unsigned int new_mask = 0;
	unsigned long flags;
	int rc = 0;

	DPRINTK("ENTER\n");

	/* For PATA drive side cable detection to work, IDENTIFY must
	 * be done backwards such that PDIAG- is released by the slave
	 * device before the master device is identified.
	 */
	ata_link_for_each_dev_reverse(dev, link) {
		unsigned int action = ata_eh_dev_action(dev);
		unsigned int readid_flags = 0;

		if (ehc->i.flags & ATA_EHI_DID_RESET)
			readid_flags |= ATA_READID_POSTRESET;

		if ((action & ATA_EH_REVALIDATE) && ata_dev_enabled(dev)) {
			WARN_ON(dev->class == ATA_DEV_PMP);

			if (ata_link_offline(link)) {
				rc = -EIO;
				goto err;
			}

			ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
			rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
						readid_flags);
			if (rc)
				goto err;

			ata_eh_done(link, dev, ATA_EH_REVALIDATE);

			/* Configuration may have changed, reconfigure
			 * transfer mode.
			 */
			ehc->i.flags |= ATA_EHI_SETMODE;

			/* schedule the scsi_rescan_device() here */
			queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
		} else if (dev->class == ATA_DEV_UNKNOWN &&
			   ehc->tries[dev->devno] &&
			   ata_class_enabled(ehc->classes[dev->devno])) {
			dev->class = ehc->classes[dev->devno];

			if (dev->class == ATA_DEV_PMP)
				rc = sata_pmp_attach(dev);
			else
				rc = ata_dev_read_id(dev, &dev->class,
						     readid_flags, dev->id);
			switch (rc) {
			case 0:
				new_mask |= 1 << dev->devno;
				break;
			case -ENOENT:
				/* IDENTIFY was issued to non-existent
				 * device.  No need to reset.  Just
				 * thaw and kill the device.
				 */
				ata_eh_thaw_port(ap);
				dev->class = ATA_DEV_UNKNOWN;
				break;
			default:
				dev->class = ATA_DEV_UNKNOWN;
				goto err;
			}
		}
	}

	/* PDIAG- should have been released, ask cable type if post-reset */
	if (ata_is_host_link(link) && ap->ops->cable_detect &&
	    (ehc->i.flags & ATA_EHI_DID_RESET))
		ap->cbl = ap->ops->cable_detect(ap);

	/* Configure new devices forward such that user doesn't see
	 * device detection messages backwards.
	 */
	ata_link_for_each_dev(dev, link) {
		if (!(new_mask & (1 << dev->devno)) ||
		    dev->class == ATA_DEV_PMP)
			continue;

		ehc->i.flags |= ATA_EHI_PRINTINFO;
		rc = ata_dev_configure(dev);
		ehc->i.flags &= ~ATA_EHI_PRINTINFO;
		if (rc)
			goto err;

		spin_lock_irqsave(ap->lock, flags);
		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
		spin_unlock_irqrestore(ap->lock, flags);

		/* new device discovered, configure xfermode */
		ehc->i.flags |= ATA_EHI_SETMODE;
	}

	return 0;

 err:
	*r_failed_dev = dev;
	DPRINTK("EXIT rc=%d\n", rc);
	return rc;
}

static int ata_link_nr_enabled(struct ata_link *link)
{
	struct ata_device *dev;
	int cnt = 0;

	ata_link_for_each_dev(dev, link)
		if (ata_dev_enabled(dev))
			cnt++;
	return cnt;
}

static int ata_link_nr_vacant(struct ata_link *link)
{
	struct ata_device *dev;
	int cnt = 0;

	ata_link_for_each_dev(dev, link)
		if (dev->class == ATA_DEV_UNKNOWN)
			cnt++;
	return cnt;
}

static int ata_eh_skip_recovery(struct ata_link *link)
{
	struct ata_eh_context *ehc = &link->eh_context;
	struct ata_device *dev;

	/* skip disabled links */
	if (link->flags & ATA_LFLAG_DISABLED)
		return 1;

	/* thaw frozen port, resume link and recover failed devices */
	if ((link->ap->pflags & ATA_PFLAG_FROZEN) ||
	    (ehc->i.flags & ATA_EHI_RESUME_LINK) || ata_link_nr_enabled(link))
		return 0;

	/* skip if class codes for all vacant slots are ATA_DEV_NONE */
	ata_link_for_each_dev(dev, link) {
		if (dev->class == ATA_DEV_UNKNOWN &&
		    ehc->classes[dev->devno] != ATA_DEV_NONE)
			return 0;
	}

	return 1;
}

static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
{
	struct ata_eh_context *ehc = &dev->link->eh_context;

	ehc->tries[dev->devno]--;

	switch (err) {
	case -ENODEV:
		/* device missing or wrong IDENTIFY data, schedule probing */
		ehc->i.probe_mask |= (1 << dev->devno);
	case -EINVAL:
		/* give it just one more chance */
		ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
	case -EIO:
		if (ehc->tries[dev->devno] == 1 && dev->pio_mode > XFER_PIO_0) {
			/* This is the last chance, better to slow
			 * down than lose it.
			 */
			sata_down_spd_limit(dev->link);
			ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
		}
	}

	if (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {
		/* disable device if it has used up all its chances */
		ata_dev_disable(dev);

		/* detach if offline */
		if (ata_link_offline(dev->link))
			ata_eh_detach_dev(dev);

		/* probe if requested */
		if ((ehc->i.probe_mask & (1 << dev->devno)) &&
		    !(ehc->did_probe_mask & (1 << dev->devno))) {
			ata_eh_detach_dev(dev);
			ata_dev_init(dev);

			ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
			ehc->did_probe_mask |= (1 << dev->devno);
			ehc->i.action |= ATA_EH_SOFTRESET;
		}

		return 1;
	} else {
		/* soft didn't work?  be haaaaard */
		if (ehc->i.flags & ATA_EHI_DID_RESET)
			ehc->i.action |= ATA_EH_HARDRESET;
		else
			ehc->i.action |= ATA_EH_SOFTRESET;

		return 0;
	}
}

/**
 *	ata_eh_recover - recover host port after error
 *	@ap: host port to recover
 *	@prereset: prereset method (can be NULL)
 *	@softreset: softreset method (can be NULL)
 *	@hardreset: hardreset method (can be NULL)
 *	@postreset: postreset method (can be NULL)
 *	@r_failed_link: out parameter for failed link
 *
 *	This is the alpha and omega, eum and yang, heart and soul of
 *	libata exception handling.  On entry, actions required to
 *	recover each link and hotplug requests are recorded in the
 *	link's eh_context.  This function executes all the operations
 *	with appropriate retrials and fallbacks to resurrect failed
 *	devices, detach goners and greet newcomers.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).
 *
 *	RETURNS:
 *	0 on success, -errno on failure.
 */
int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
		   ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
		   ata_postreset_fn_t postreset,
		   struct ata_link **r_failed_link)
{
	struct ata_link *link;
	struct ata_device *dev;
	int nr_failed_devs, nr_disabled_devs;
	int reset, rc;
	unsigned long flags;

	DPRINTK("ENTER\n");

	/* prep for recovery */
	ata_port_for_each_link(link, ap) {
		struct ata_eh_context *ehc = &link->eh_context;

		/* re-enable link? */
		if (ehc->i.action & ATA_EH_ENABLE_LINK) {
			ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
			spin_lock_irqsave(ap->lock, flags);
			link->flags &= ~ATA_LFLAG_DISABLED;
			spin_unlock_irqrestore(ap->lock, flags);
			ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
		}

		ata_link_for_each_dev(dev, link) {
			if (link->flags & ATA_LFLAG_NO_RETRY)
				ehc->tries[dev->devno] = 1;
			else
				ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;

			/* collect port action mask recorded in dev actions */
			ehc->i.action |= ehc->i.dev_action[dev->devno] &
					 ~ATA_EH_PERDEV_MASK;
			ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;

			/* process hotplug request */
			if (dev->flags & ATA_DFLAG_DETACH)
				ata_eh_detach_dev(dev);

			if (!ata_dev_enabled(dev) &&
			    ((ehc->i.probe_mask & (1 << dev->devno)) &&
			     !(ehc->did_probe_mask & (1 << dev->devno)))) {
				ata_eh_detach_dev(dev);
				ata_dev_init(dev);
				ehc->did_probe_mask |= (1 << dev->devno);
				ehc->i.action |= ATA_EH_SOFTRESET;
			}
		}
	}

 retry:
	rc = 0;
	nr_failed_devs = 0;
	nr_disabled_devs = 0;
	reset = 0;

	/* if UNLOADING, finish immediately */
	if (ap->pflags & ATA_PFLAG_UNLOADING)
		goto out;

	/* prep for EH */
	ata_port_for_each_link(link, ap) {
		struct ata_eh_context *ehc = &link->eh_context;

		/* skip EH if possible. */
		if (ata_eh_skip_recovery(link))
			ehc->i.action = 0;

		/* do we need to reset? */
		if (ehc->i.action & ATA_EH_RESET_MASK)
			reset = 1;

		ata_link_for_each_dev(dev, link)
			ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
	}

	/* reset */
	if (reset) {
		/* if PMP is attached, this function only deals with
		 * downstream links, port should stay thawed.
		 */
		if (!ap->nr_pmp_links)
			ata_eh_freeze_port(ap);

		ata_port_for_each_link(link, ap) {
			struct ata_eh_context *ehc = &link->eh_context;

			if (!(ehc->i.action & ATA_EH_RESET_MASK))
				continue;

			rc = ata_eh_reset(link, ata_link_nr_vacant(link),
					  prereset, softreset, hardreset,
					  postreset);
			if (rc) {
				ata_link_printk(link, KERN_ERR,
						"reset failed, giving up\n");
				goto out;
			}
		}

		if (!ap->nr_pmp_links)
			ata_eh_thaw_port(ap);
	}

	/* the rest */
	ata_port_for_each_