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 bc6695e3c848..ffd98e4e65b4 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);