libata: beef up iterators

There currently are the following looping constructs.

* __ata_port_for_each_link() for all available links
* ata_port_for_each_link() for edge links
* ata_link_for_each_dev() for all devices
* ata_link_for_each_dev_reverse() for all devices in reverse order

Now there's a need for looping construct which is similar to
__ata_port_for_each_link() but iterates over PMP links before the host
link.  Instead of adding another one with long name, do the following
cleanup.

* Implement and export ata_link_next() and ata_dev_next() which take
  @mode parameter and can be used to build custom loop.
* Implement ata_for_each_link() and ata_for_each_dev() which take
  looping mode explicitly.

The following iteration modes are implemented.

* ATA_LITER_EDGE		: loop over edge links
* ATA_LITER_HOST_FIRST		: loop over all links, host link first
* ATA_LITER_PMP_FIRST		: loop over all links, PMP links first

* ATA_DITER_ENABLED		: loop over enabled devices
* ATA_DITER_ENABLED_REVERSE	: loop over enabled devices in reverse order
* ATA_DITER_ALL			: loop over all devices
* ATA_DITER_ALL_REVERSE		: loop over all devices in reverse order

This change removes exlicit device enabledness checks from many loops
and makes it clear which ones are iterated over in which direction.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 122 insertions, 61 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index bc6695e3c84..ffd98e4e65b 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -163,43 +163,119 @@ MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);
 
 
-/*
- * Iterator helpers.  Don't use directly.
+/**
+ *	ata_link_next - link iteration helper
+ *	@link: the previous link, NULL to start
+ *	@ap: ATA port containing links to iterate
+ *	@mode: iteration mode, one of ATA_LITER_*
+ *
+ *	LOCKING:
+ *	Host lock or EH context.
  *
- * LOCKING:
- * Host lock or EH context.
+ *	RETURNS:
+ *	Pointer to the next link.
  */
-struct ata_link *__ata_port_next_link(struct ata_port *ap,
-				      struct ata_link *link, bool dev_only)
+struct ata_link *ata_link_next(struct ata_link *link, struct ata_port *ap,
+			       enum ata_link_iter_mode mode)
 {
+	BUG_ON(mode != ATA_LITER_EDGE &&
+	       mode != ATA_LITER_PMP_FIRST && mode != ATA_LITER_HOST_FIRST);
+
 	/* NULL link indicates start of iteration */
-	if (!link) {
-		if (dev_only && sata_pmp_attached(ap))
-			return ap->pmp_link;
-		return &ap->link;
-	}
+	if (!link)
+		switch (mode) {
+		case ATA_LITER_EDGE:
+		case ATA_LITER_PMP_FIRST:
+			if (sata_pmp_attached(ap))
+				return ap->pmp_link;
+			/* fall through */
+		case ATA_LITER_HOST_FIRST:
+			return &ap->link;
+		}
 
-	/* we just iterated over the host master link, what's next? */
-	if (link == &ap->link) {
-		if (!sata_pmp_attached(ap)) {
-			if (unlikely(ap->slave_link) && !dev_only)
+	/* we just iterated over the host link, what's next? */
+	if (link == &ap->link)
+		switch (mode) {
+		case ATA_LITER_HOST_FIRST:
+			if (sata_pmp_attached(ap))
+				return ap->pmp_link;
+			/* fall through */
+		case ATA_LITER_PMP_FIRST:
+			if (unlikely(ap->slave_link))
 				return ap->slave_link;
+			/* fall through */
+		case ATA_LITER_EDGE:
 			return NULL;
 		}
-		return ap->pmp_link;
-	}
 
 	/* slave_link excludes PMP */
 	if (unlikely(link == ap->slave_link))
 		return NULL;
 
-	/* iterate to the next PMP link */
+	/* we were over a PMP link */
 	if (++link < ap->pmp_link + ap->nr_pmp_links)
 		return link;
+
+	if (mode == ATA_LITER_PMP_FIRST)
+		return &ap->link;
+
 	return NULL;
 }
 
 /**
+ *	ata_dev_next - device iteration helper
+ *	@dev: the previous device, NULL to start
+ *	@link: ATA link containing devices to iterate
+ *	@mode: iteration mode, one of ATA_DITER_*
+ *
+ *	LOCKING:
+ *	Host lock or EH context.
+ *
+ *	RETURNS:
+ *	Pointer to the next device.
+ */
+struct ata_device *ata_dev_next(struct ata_device *dev, struct ata_link *link,
+				enum ata_dev_iter_mode mode)
+{
+	BUG_ON(mode != ATA_DITER_ENABLED && mode != ATA_DITER_ENABLED_REVERSE &&
+	       mode != ATA_DITER_ALL && mode != ATA_DITER_ALL_REVERSE);
+
+	/* NULL dev indicates start of iteration */
+	if (!dev)
+		switch (mode) {
+		case ATA_DITER_ENABLED:
+		case ATA_DITER_ALL:
+			dev = link->device;
+			goto check;
+		case ATA_DITER_ENABLED_REVERSE:
+		case ATA_DITER_ALL_REVERSE:
+			dev = link->device + ata_link_max_devices(link) - 1;
+			goto check;
+		}
+
+ next:
+	/* move to the next one */
+	switch (mode) {
+	case ATA_DITER_ENABLED:
+	case ATA_DITER_ALL:
+		if (++dev < link->device + ata_link_max_devices(link))
+			goto check;
+		return NULL;
+	case ATA_DITER_ENABLED_REVERSE:
+	case ATA_DITER_ALL_REVERSE:
+		if (--dev >= link->device)
+			goto check;
+		return NULL;
+	}
+
+ check:
+	if ((mode == ATA_DITER_ENABLED || mode == ATA_DITER_ENABLED_REVERSE) &&
+	    !ata_dev_enabled(dev))
+		goto next;
+	return dev;
+}
+
+/**
  *	ata_dev_phys_link - find physical link for a device
  *	@dev: ATA device to look up physical link for
  *
@@ -1107,8 +1183,8 @@ static void ata_lpm_enable(struct ata_host *host)
 
 	for (i = 0; i < host->n_ports; i++) {
 		ap = host->ports[i];
-		ata_port_for_each_link(link, ap) {
-			ata_link_for_each_dev(dev, link)
+		ata_for_each_link(link, ap, EDGE) {
+			ata_for_each_dev(dev, link, ALL)
 				ata_dev_disable_pm(dev);
 		}
 	}
@@ -2594,11 +2670,11 @@ int ata_bus_probe(struct ata_port *ap)
 
 	ata_port_probe(ap);
 
-	ata_link_for_each_dev(dev, &ap->link)
+	ata_for_each_dev(dev, &ap->link, ALL)
 		tries[dev->devno] = ATA_PROBE_MAX_TRIES;
 
  retry:
-	ata_link_for_each_dev(dev, &ap->link) {
+	ata_for_each_dev(dev, &ap->link, ALL) {
 		/* If we issue an SRST then an ATA drive (not ATAPI)
 		 * may change configuration and be in PIO0 timing. If
 		 * we do a hard reset (or are coming from power on)
@@ -2620,7 +2696,7 @@ int ata_bus_probe(struct ata_port *ap)
 	/* reset and determine device classes */
 	ap->ops->phy_reset(ap);
 
-	ata_link_for_each_dev(dev, &ap->link) {
+	ata_for_each_dev(dev, &ap->link, ALL) {
 		if (!(ap->flags & ATA_FLAG_DISABLED) &&
 		    dev->class != ATA_DEV_UNKNOWN)
 			classes[dev->devno] = dev->class;
@@ -2636,7 +2712,7 @@ int ata_bus_probe(struct ata_port *ap)
 	   specific sequence bass-ackwards so that PDIAG- is released by
 	   the slave device */
 
-	ata_link_for_each_dev_reverse(dev, &ap->link) {
+	ata_for_each_dev(dev, &ap->link, ALL_REVERSE) {
 		if (tries[dev->devno])
 			dev->class = classes[dev->devno];
 
@@ -2653,24 +2729,19 @@ int ata_bus_probe(struct ata_port *ap)
 	if (ap->ops->cable_detect)
 		ap->cbl = ap->ops->cable_detect(ap);
 
-	/* We may have SATA bridge glue hiding here irrespective of the
-	   reported cable types and sensed types */
-	ata_link_for_each_dev(dev, &ap->link) {
-		if (!ata_dev_enabled(dev))
-			continue;
-		/* SATA drives indicate we have a bridge. We don't know which
-		   end of the link the bridge is which is a problem */
+	/* We may have SATA bridge glue hiding here irrespective of
+	 * the reported cable types and sensed types.  When SATA
+	 * drives indicate we have a bridge, we don't know which end
+	 * of the link the bridge is which is a problem.
+	 */
+	ata_for_each_dev(dev, &ap->link, ENABLED)
 		if (ata_id_is_sata(dev->id))
 			ap->cbl = ATA_CBL_SATA;
-	}
 
 	/* After the identify sequence we can now set up the devices. We do
 	   this in the normal order so that the user doesn't get confused */
 
-	ata_link_for_each_dev(dev, &ap->link) {
-		if (!ata_dev_enabled(dev))
-			continue;
-
+	ata_for_each_dev(dev, &ap->link, ENABLED) {
 		ap->link.eh_context.i.flags |= ATA_EHI_PRINTINFO;
 		rc = ata_dev_configure(dev);
 		ap->link.eh_context.i.flags &= ~ATA_EHI_PRINTINFO;
@@ -2683,9 +2754,8 @@ int ata_bus_probe(struct ata_port *ap)
 	if (rc)
 		goto fail;
 
-	ata_link_for_each_dev(dev, &ap->link)
-		if (ata_dev_enabled(dev))
-			return 0;
+	ata_for_each_dev(dev, &ap->link, ENABLED)
+		return 0;
 
 	/* no device present, disable port */
 	ata_port_disable(ap);
@@ -3331,13 +3401,10 @@ int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
 	int rc = 0, used_dma = 0, found = 0;
 
 	/* step 1: calculate xfer_mask */
-	ata_link_for_each_dev(dev, link) {
+	ata_for_each_dev(dev, link, ENABLED) {
 		unsigned long pio_mask, dma_mask;
 		unsigned int mode_mask;
 
-		if (!ata_dev_enabled(dev))
-			continue;
-
 		mode_mask = ATA_DMA_MASK_ATA;
 		if (dev->class == ATA_DEV_ATAPI)
 			mode_mask = ATA_DMA_MASK_ATAPI;
@@ -3366,10 +3433,7 @@ int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
 		goto out;
 
 	/* step 2: always set host PIO timings */
-	ata_link_for_each_dev(dev, link) {
-		if (!ata_dev_enabled(dev))
-			continue;
-
+	ata_for_each_dev(dev, link, ENABLED) {
 		if (dev->pio_mode == 0xff) {
 			ata_dev_printk(dev, KERN_WARNING, "no PIO support\n");
 			rc = -EINVAL;
@@ -3383,8 +3447,8 @@ int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
 	}
 
 	/* step 3: set host DMA timings */
-	ata_link_for_each_dev(dev, link) {
-		if (!ata_dev_enabled(dev) || !ata_dma_enabled(dev))
+	ata_for_each_dev(dev, link, ENABLED) {
+		if (!ata_dma_enabled(dev))
 			continue;
 
 		dev->xfer_mode = dev->dma_mode;
@@ -3394,11 +3458,7 @@ int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
 	}
 
 	/* step 4: update devices' xfer mode */
-	ata_link_for_each_dev(dev, link) {
-		/* don't update suspended devices' xfer mode */
-		if (!ata_dev_enabled(dev))
-			continue;
-
+	ata_for_each_dev(dev, link, ENABLED) {
 		rc = ata_dev_set_mode(dev);
 		if (rc)
 			goto out;
@@ -4263,9 +4323,9 @@ static int cable_is_40wire(struct ata_port *ap)
 	 * - if you have a non detect capable drive you don't want it
 	 *   to colour the choice
 	 */
-	ata_port_for_each_link(link, ap) {
-		ata_link_for_each_dev(dev, link) {
-			if (ata_dev_enabled(dev) && !ata_is_40wire(dev))
+	ata_for_each_link(link, ap, EDGE) {
+		ata_for_each_dev(dev, link, ENABLED) {
+			if (!ata_is_40wire(dev))
 				return 0;
 		}
 	}
@@ -5218,7 +5278,7 @@ static int ata_host_request_pm(struct ata_host *host, pm_message_t mesg,
 		}
 
 		ap->pflags |= ATA_PFLAG_PM_PENDING;
-		__ata_port_for_each_link(link, ap) {
+		ata_for_each_link(link, ap, HOST_FIRST) {
 			link->eh_info.action |= action;
 			link->eh_info.flags |= ehi_flags;
 		}
@@ -6063,9 +6123,9 @@ static void ata_port_detach(struct ata_port *ap)
 	/* EH is now guaranteed to see UNLOADING - EH context belongs
 	 * to us.  Restore SControl and disable all existing devices.
 	 */
-	__ata_port_for_each_link(link, ap) {
+	ata_for_each_link(link, ap, HOST_FIRST) {
 		sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
-		ata_link_for_each_dev(dev, link)
+		ata_for_each_dev(dev, link, ALL)
 			ata_dev_disable(dev);
 	}
 
@@ -6528,7 +6588,8 @@ EXPORT_SYMBOL_GPL(ata_base_port_ops);
 EXPORT_SYMBOL_GPL(sata_port_ops);
 EXPORT_SYMBOL_GPL(ata_dummy_port_ops);
 EXPORT_SYMBOL_GPL(ata_dummy_port_info);
-EXPORT_SYMBOL_GPL(__ata_port_next_link);
+EXPORT_SYMBOL_GPL(ata_link_next);
+EXPORT_SYMBOL_GPL(ata_dev_next);
 EXPORT_SYMBOL_GPL(ata_std_bios_param);
 EXPORT_SYMBOL_GPL(ata_host_init);
 EXPORT_SYMBOL_GPL(ata_host_alloc);