244 lines
7.2 KiB
C
244 lines
7.2 KiB
C
/*
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* Descending-priority-sorted double-linked list
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*
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* (C) 2002-2003 Intel Corp
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* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
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*
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* 2001-2005 (c) MontaVista Software, Inc.
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* Daniel Walker <dwalker@mvista.com>
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*
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* (C) 2005 Thomas Gleixner <tglx@linutronix.de>
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*
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* Simplifications of the original code by
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* Oleg Nesterov <oleg@tv-sign.ru>
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*
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* Licensed under the FSF's GNU Public License v2 or later.
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*
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* Based on simple lists (include/linux/list.h).
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*
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* This is a priority-sorted list of nodes; each node has a
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* priority from INT_MIN (highest) to INT_MAX (lowest).
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*
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* Addition is O(K), removal is O(1), change of priority of a node is
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* O(K) and K is the number of RT priority levels used in the system.
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* (1 <= K <= 99)
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*
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* This list is really a list of lists:
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*
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* - The tier 1 list is the prio_list, different priority nodes.
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*
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* - The tier 2 list is the node_list, serialized nodes.
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*
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* Simple ASCII art explanation:
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*
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* |HEAD |
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* | |
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* |prio_list.prev|<------------------------------------|
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* |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-|
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* |10 | |10| |21| |21| |21| |40| (prio)
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* | | | | | | | | | | | |
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* | | | | | | | | | | | |
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* |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
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* |node_list.prev|<------------------------------------|
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*
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* The nodes on the prio_list list are sorted by priority to simplify
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* the insertion of new nodes. There are no nodes with duplicate
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* priorites on the list.
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*
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* The nodes on the node_list is ordered by priority and can contain
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* entries which have the same priority. Those entries are ordered
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* FIFO
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*
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* Addition means: look for the prio_list node in the prio_list
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* for the priority of the node and insert it before the node_list
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* entry of the next prio_list node. If it is the first node of
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* that priority, add it to the prio_list in the right position and
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* insert it into the serialized node_list list
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*
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* Removal means remove it from the node_list and remove it from
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* the prio_list if the node_list list_head is non empty. In case
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* of removal from the prio_list it must be checked whether other
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* entries of the same priority are on the list or not. If there
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* is another entry of the same priority then this entry has to
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* replace the removed entry on the prio_list. If the entry which
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* is removed is the only entry of this priority then a simple
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* remove from both list is sufficient.
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*
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* INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
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* is lowest priority.
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*
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* No locking is done, up to the caller.
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*
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*/
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#ifndef _LINUX_PLIST_H_
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#define _LINUX_PLIST_H_
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/spinlock_types.h>
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struct plist_head {
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struct list_head prio_list;
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struct list_head node_list;
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#ifdef CONFIG_DEBUG_PI_LIST
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spinlock_t *lock;
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#endif
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};
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struct plist_node {
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int prio;
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struct plist_head plist;
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};
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#ifdef CONFIG_DEBUG_PI_LIST
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# define PLIST_HEAD_LOCK_INIT(_lock) .lock = _lock
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#else
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# define PLIST_HEAD_LOCK_INIT(_lock)
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#endif
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#define _PLIST_HEAD_INIT(head) \
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.prio_list = LIST_HEAD_INIT((head).prio_list), \
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.node_list = LIST_HEAD_INIT((head).node_list)
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/**
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* PLIST_HEAD_INIT - static struct plist_head initializer
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* @head: struct plist_head variable name
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* @_lock: lock to initialize for this list
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*/
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#define PLIST_HEAD_INIT(head, _lock) \
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{ \
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_PLIST_HEAD_INIT(head), \
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PLIST_HEAD_LOCK_INIT(&(_lock)) \
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}
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/**
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* PLIST_NODE_INIT - static struct plist_node initializer
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* @node: struct plist_node variable name
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* @__prio: initial node priority
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*/
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#define PLIST_NODE_INIT(node, __prio) \
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{ \
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.prio = (__prio), \
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.plist = { _PLIST_HEAD_INIT((node).plist) }, \
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}
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/**
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* plist_head_init - dynamic struct plist_head initializer
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* @head: &struct plist_head pointer
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* @lock: list spinlock, remembered for debugging
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*/
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static inline void
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plist_head_init(struct plist_head *head, spinlock_t *lock)
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{
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INIT_LIST_HEAD(&head->prio_list);
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INIT_LIST_HEAD(&head->node_list);
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#ifdef CONFIG_DEBUG_PI_LIST
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head->lock = lock;
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#endif
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}
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/**
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* plist_node_init - Dynamic struct plist_node initializer
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* @node: &struct plist_node pointer
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* @prio: initial node priority
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*/
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static inline void plist_node_init(struct plist_node *node, int prio)
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{
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node->prio = prio;
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plist_head_init(&node->plist, NULL);
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}
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extern void plist_add(struct plist_node *node, struct plist_head *head);
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extern void plist_del(struct plist_node *node, struct plist_head *head);
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/**
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* plist_for_each - iterate over the plist
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* @pos: the type * to use as a loop counter
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* @head: the head for your list
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*/
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#define plist_for_each(pos, head) \
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list_for_each_entry(pos, &(head)->node_list, plist.node_list)
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/**
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* plist_for_each_safe - iterate safely over a plist of given type
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* @pos: the type * to use as a loop counter
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* @n: another type * to use as temporary storage
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* @head: the head for your list
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*
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* Iterate over a plist of given type, safe against removal of list entry.
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*/
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#define plist_for_each_safe(pos, n, head) \
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list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)
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/**
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* plist_for_each_entry - iterate over list of given type
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* @pos: the type * to use as a loop counter
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* @head: the head for your list
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* @mem: the name of the list_struct within the struct
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*/
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#define plist_for_each_entry(pos, head, mem) \
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list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list)
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/**
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* plist_for_each_entry_safe - iterate safely over list of given type
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* @pos: the type * to use as a loop counter
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* @n: another type * to use as temporary storage
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* @head: the head for your list
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* @m: the name of the list_struct within the struct
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*
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* Iterate over list of given type, safe against removal of list entry.
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*/
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#define plist_for_each_entry_safe(pos, n, head, m) \
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list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)
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/**
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* plist_head_empty - return !0 if a plist_head is empty
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* @head: &struct plist_head pointer
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*/
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static inline int plist_head_empty(const struct plist_head *head)
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{
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return list_empty(&head->node_list);
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}
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/**
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* plist_node_empty - return !0 if plist_node is not on a list
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* @node: &struct plist_node pointer
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*/
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static inline int plist_node_empty(const struct plist_node *node)
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{
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return plist_head_empty(&node->plist);
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}
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/* All functions below assume the plist_head is not empty. */
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/**
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* plist_first_entry - get the struct for the first entry
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* @head: the &struct plist_head pointer
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* @type: the type of the struct this is embedded in
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* @member: the name of the list_struct within the struct
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*/
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#ifdef CONFIG_DEBUG_PI_LIST
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# define plist_first_entry(head, type, member) \
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({ \
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WARN_ON(plist_head_empty(head)); \
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container_of(plist_first(head), type, member); \
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})
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#else
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# define plist_first_entry(head, type, member) \
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container_of(plist_first(head), type, member)
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#endif
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/**
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* plist_first - return the first node (and thus, highest priority)
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* @head: the &struct plist_head pointer
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*
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* Assumes the plist is _not_ empty.
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*/
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static inline struct plist_node* plist_first(const struct plist_head *head)
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{
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return list_entry(head->node_list.next,
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struct plist_node, plist.node_list);
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}
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#endif
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