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Commit 12e4d0cc authored by James Bottomley's avatar James Bottomley Committed by Rafael J. Wysocki
Browse files

plist: Add plist_last 



plist is currently used by the scheduler, which only needs to know the
highest item in the list.  This adds plist_last which allows you to
find the lowest.  This is necessary for using plists to implement a
fast search of dynamic ranges in pm_qos which can have both highest
and lowest criteria.

Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent c125e96f

include/linux/plist.h

+29 −0
Original line number Diff line number Diff line
@@ -259,6 +259,23 @@ static inline int plist_node_empty(const struct plist_node *node) 
	container_of(plist_first(head), type, member)

#endif



/**

 * plist_last_entry - get the struct for the last entry

 * @head:	the &struct plist_head pointer

 * @type:	the type of the struct this is embedded in

 * @member:	the name of the list_struct within the struct

 */

#ifdef CONFIG_DEBUG_PI_LIST

# define plist_last_entry(head, type, member)	\

({ \

	WARN_ON(plist_head_empty(head)); \

	container_of(plist_last(head), type, member); \

})

#else

# define plist_last_entry(head, type, member)	\

	container_of(plist_last(head), type, member)

#endif



/**

 * plist_first - return the first node (and thus, highest priority)

 * @head:	the &struct plist_head pointer
@@ -271,4 +288,16 @@ static inline struct plist_node *plist_first(const struct plist_head *head) 
			  struct plist_node, plist.node_list);

}



/**

 * plist_last - return the last node (and thus, lowest priority)

 * @head:	the &struct plist_head pointer

 *

 * Assumes the plist is _not_ empty.

 */

static inline struct plist_node *plist_last(const struct plist_head *head)

{

	return list_entry(head->node_list.prev,

			  struct plist_node, plist.node_list);

}



#endif