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author | James Bottomley <James.Bottomley@suse.de> | 2010-07-01 23:46:36 +0400 |
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committer | Rafael J. Wysocki <rjw@sisk.pl> | 2010-07-19 03:58:48 +0400 |
commit | 12e4d0cc2e0a776a526c93bb2fcb9267abc6e0b1 (patch) | |
tree | b90af0838639dc21da686960d0ae7eaa9c5fd06a /include/linux/plist.h | |
parent | c125e96f044427f38d106fab7bc5e4a5e6a18262 (diff) | |
download | linux-12e4d0cc2e0a776a526c93bb2fcb9267abc6e0b1.tar.xz |
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 <James.Bottomley@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'include/linux/plist.h')
-rw-r--r-- | include/linux/plist.h | 29 |
1 files changed, 29 insertions, 0 deletions
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 @@ -260,6 +260,23 @@ static inline int plist_node_empty(const struct plist_node *node) #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 |