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libata: beef up iterators

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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>
This commit is contained in:
Tejun Heo 2008-11-03 20:03:17 +09:00 • committed by Jeff Garzik
parent 3c92ec8ae9
commit 1eca4365be
15 changed files with 302 additions and 235 deletions
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68
include/linux/libata.h
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@ -1285,26 +1285,62 @@ static inline int ata_link_active(struct ata_link *link)
return ata_tag_valid(link->active_tag) || link->sactive;
}
extern struct ata_link *__ata_port_next_link(struct ata_port *ap,
struct ata_link *link,
bool dev_only);
/*
* Iterators
*
* ATA_LITER_* constants are used to select link iteration mode and
* ATA_DITER_* device iteration mode.
*
* For a custom iteration directly using ata_{link|dev}_next(), if
* @link or @dev, respectively, is NULL, the first element is
* returned. @dev and @link can be any valid device or link and the
* next element according to the iteration mode will be returned.
* After the last element, NULL is returned.
*/
enum ata_link_iter_mode {
ATA_LITER_EDGE, /* if present, PMP links only; otherwise,
* host link. no slave link */
ATA_LITER_HOST_FIRST, /* host link followed by PMP or slave links */
ATA_LITER_PMP_FIRST, /* PMP links followed by host link,
* slave link still comes after host link */
};
#define __ata_port_for_each_link(link, ap) \
for ((link) = __ata_port_next_link((ap), NULL, false); (link); \
(link) = __ata_port_next_link((ap), (link), false))
enum ata_dev_iter_mode {
ATA_DITER_ENABLED,
ATA_DITER_ENABLED_REVERSE,
ATA_DITER_ALL,
ATA_DITER_ALL_REVERSE,
};
#define ata_port_for_each_link(link, ap) \
for ((link) = __ata_port_next_link((ap), NULL, true); (link); \
(link) = __ata_port_next_link((ap), (link), true))
extern struct ata_link *ata_link_next(struct ata_link *link,
struct ata_port *ap,
enum ata_link_iter_mode mode);
#define ata_link_for_each_dev(dev, link) \
for ((dev) = (link)->device; \
(dev) < (link)->device + ata_link_max_devices(link) || ((dev) = NULL); \
(dev)++)
extern struct ata_device *ata_dev_next(struct ata_device *dev,
struct ata_link *link,
enum ata_dev_iter_mode mode);
#define ata_link_for_each_dev_reverse(dev, link) \
for ((dev) = (link)->device + ata_link_max_devices(link) - 1; \
(dev) >= (link)->device || ((dev) = NULL); (dev)--)
/*
* Shortcut notation for iterations
*
* ata_for_each_link() iterates over each link of @ap according to
* @mode. @link points to the current link in the loop. @link is
* NULL after loop termination. ata_for_each_dev() works the same way
* except that it iterates over each device of @link.
*
* Note that the mode prefixes ATA_{L|D}ITER_ shouldn't need to be
* specified when using the following shorthand notations. Only the
* mode itself (EDGE, HOST_FIRST, ENABLED, etc...) should be
* specified. This not only increases brevity but also makes it
* impossible to use ATA_LITER_* for device iteration or vice-versa.
*/
#define ata_for_each_link(link, ap, mode) \
for ((link) = ata_link_next(NULL, (ap), ATA_LITER_##mode); (link); \
(link) = ata_link_next((link), (ap), ATA_LITER_##mode))
#define ata_for_each_dev(dev, link, mode) \
for ((dev) = ata_dev_next(NULL, (link), ATA_DITER_##mode); (dev); \
(dev) = ata_dev_next((dev), (link), ATA_DITER_##mode))
/**
* ata_ncq_enabled - Test whether NCQ is enabled