From 12e4d0cc2e0a776a526c93bb2fcb9267abc6e0b1 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Thu, 1 Jul 2010 21:46:36 +0200 Subject: [PATCH] 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: James Bottomley Signed-off-by: Rafael J. Wysocki --- include/linux/plist.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/include/linux/plist.h b/include/linux/plist.h index 6898985e7b38..7254eda078e5 100644 --- a/include/linux/plist.h +++ b/include/linux/plist.h @@ -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