Commit 77ba89c5 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds

[PATCH] pi-futex: add plist implementation

Add the priority-sorted list (plist) implementation.
Signed-off-by: 's avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: 's avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: 's avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: 's avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@osdl.org>
parent 8eb94f80
/*
* Descending-priority-sorted double-linked list
*
* (C) 2002-2003 Intel Corp
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
*
* 2001-2005 (c) MontaVista Software, Inc.
* Daniel Walker <dwalker@mvista.com>
*
* (C) 2005 Thomas Gleixner <tglx@linutronix.de>
*
* Simplifications of the original code by
* Oleg Nesterov <oleg@tv-sign.ru>
*
* Licensed under the FSF's GNU Public License v2 or later.
*
* Based on simple lists (include/linux/list.h).
*
* This is a priority-sorted list of nodes; each node has a
* priority from INT_MIN (highest) to INT_MAX (lowest).
*
* Addition is O(K), removal is O(1), change of priority of a node is
* O(K) and K is the number of RT priority levels used in the system.
* (1 <= K <= 99)
*
* This list is really a list of lists:
*
* - The tier 1 list is the prio_list, different priority nodes.
*
* - The tier 2 list is the node_list, serialized nodes.
*
* Simple ASCII art explanation:
*
* |HEAD |
* | |
* |prio_list.prev|<------------------------------------|
* |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-|
* |10 | |10| |21| |21| |21| |40| (prio)
* | | | | | | | | | | | |
* | | | | | | | | | | | |
* |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
* |node_list.prev|<------------------------------------|
*
* The nodes on the prio_list list are sorted by priority to simplify
* the insertion of new nodes. There are no nodes with duplicate
* priorites on the list.
*
* The nodes on the node_list is ordered by priority and can contain
* entries which have the same priority. Those entries are ordered
* FIFO
*
* Addition means: look for the prio_list node in the prio_list
* for the priority of the node and insert it before the node_list
* entry of the next prio_list node. If it is the first node of
* that priority, add it to the prio_list in the right position and
* insert it into the serialized node_list list
*
* Removal means remove it from the node_list and remove it from
* the prio_list if the node_list list_head is non empty. In case
* of removal from the prio_list it must be checked whether other
* entries of the same priority are on the list or not. If there
* is another entry of the same priority then this entry has to
* replace the removed entry on the prio_list. If the entry which
* is removed is the only entry of this priority then a simple
* remove from both list is sufficient.
*
* INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
* is lowest priority.
*
* No locking is done, up to the caller.
*
*/
#ifndef _LINUX_PLIST_H_
#define _LINUX_PLIST_H_
#include <linux/list.h>
#include <linux/spinlock_types.h>
struct plist_head {
struct list_head prio_list;
struct list_head node_list;
#ifdef CONFIG_DEBUG_PI_LIST
spinlock_t *lock;
#endif
};
struct plist_node {
int prio;
struct plist_head plist;
};
#ifdef CONFIG_DEBUG_PI_LIST
# define PLIST_HEAD_LOCK_INIT(_lock) .lock = _lock
#else
# define PLIST_HEAD_LOCK_INIT(_lock)
#endif
/**
* #PLIST_HEAD_INIT - static struct plist_head initializer
*
* @head: struct plist_head variable name
*/
#define PLIST_HEAD_INIT(head, _lock) \
{ \
.prio_list = LIST_HEAD_INIT((head).prio_list), \
.node_list = LIST_HEAD_INIT((head).node_list), \
PLIST_HEAD_LOCK_INIT(&(_lock)) \
}
/**
* #PLIST_NODE_INIT - static struct plist_node initializer
*
* @node: struct plist_node variable name
* @__prio: initial node priority
*/
#define PLIST_NODE_INIT(node, __prio) \
{ \
.prio = (__prio), \
.plist = PLIST_HEAD_INIT((node).plist, NULL), \
}
/**
* plist_head_init - dynamic struct plist_head initializer
*
* @head: &struct plist_head pointer
*/
static inline void
plist_head_init(struct plist_head *head, spinlock_t *lock)
{
INIT_LIST_HEAD(&head->prio_list);
INIT_LIST_HEAD(&head->node_list);
#ifdef CONFIG_DEBUG_PI_LIST
head->lock = lock;
#endif
}
/**
* plist_node_init - Dynamic struct plist_node initializer
*
* @node: &struct plist_node pointer
* @prio: initial node priority
*/
static inline void plist_node_init(struct plist_node *node, int prio)
{
node->prio = prio;
plist_head_init(&node->plist, NULL);
}
extern void plist_add(struct plist_node *node, struct plist_head *head);
extern void plist_del(struct plist_node *node, struct plist_head *head);
/**
* plist_for_each - iterate over the plist
*
* @pos1: the type * to use as a loop counter.
* @head: the head for your list.
*/
#define plist_for_each(pos, head) \
list_for_each_entry(pos, &(head)->node_list, plist.node_list)
/**
* plist_for_each_entry_safe - iterate over a plist of given type safe
* against removal of list entry
*
* @pos1: the type * to use as a loop counter.
* @n1: another type * to use as temporary storage
* @head: the head for your list.
*/
#define plist_for_each_safe(pos, n, head) \
list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)
/**
* plist_for_each_entry - iterate over list of given type
*
* @pos: the type * to use as a loop counter.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
#define plist_for_each_entry(pos, head, mem) \
list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list)
/**
* plist_for_each_entry_safe - iterate over list of given type safe against
* removal of list entry
*
* @pos: the type * to use as a loop counter.
* @n: another type * to use as temporary storage
* @head: the head for your list.
* @m: the name of the list_struct within the struct.
*/
#define plist_for_each_entry_safe(pos, n, head, m) \
list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)
/**
* plist_head_empty - return !0 if a plist_head is empty
*
* @head: &struct plist_head pointer
*/
static inline int plist_head_empty(const struct plist_head *head)
{
return list_empty(&head->node_list);
}
/**
* plist_node_empty - return !0 if plist_node is not on a list
*
* @node: &struct plist_node pointer
*/
static inline int plist_node_empty(const struct plist_node *node)
{
return plist_head_empty(&node->plist);
}
/* All functions below assume the plist_head is not empty. */
/**
* plist_first_entry - get the struct for the first entry
*
* @ptr: 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_first_entry(head, type, member) \
({ \
WARN_ON(plist_head_empty(head)); \
container_of(plist_first(head), type, member); \
})
#else
# define plist_first_entry(head, type, member) \
container_of(plist_first(head), type, member)
#endif
/**
* plist_first - return the first node (and thus, highest priority)
*
* @head: the &struct plist_head pointer
*
* Assumes the plist is _not_ empty.
*/
static inline struct plist_node* plist_first(const struct plist_head *head)
{
return list_entry(head->node_list.next,
struct plist_node, plist.node_list);
}
#endif
......@@ -86,4 +86,10 @@ config TEXTSEARCH_BM
config TEXTSEARCH_FSM
tristate
#
# plist support is select#ed if needed
#
config PLIST
boolean
endmenu
......@@ -25,6 +25,7 @@ lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o
lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
lib-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o
obj-$(CONFIG_PLIST) += plist.o
obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
ifneq ($(CONFIG_HAVE_DEC_LOCK),y)
......
/*
* lib/plist.c
*
* Descending-priority-sorted double-linked list
*
* (C) 2002-2003 Intel Corp
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
*
* 2001-2005 (c) MontaVista Software, Inc.
* Daniel Walker <dwalker@mvista.com>
*
* (C) 2005 Thomas Gleixner <tglx@linutronix.de>
*
* Simplifications of the original code by
* Oleg Nesterov <oleg@tv-sign.ru>
*
* Licensed under the FSF's GNU Public License v2 or later.
*
* Based on simple lists (include/linux/list.h).
*
* This file contains the add / del functions which are considered to
* be too large to inline. See include/linux/plist.h for further
* information.
*/
#include <linux/plist.h>
#include <linux/spinlock.h>
#ifdef CONFIG_DEBUG_PI_LIST
static void plist_check_prev_next(struct list_head *t, struct list_head *p,
struct list_head *n)
{
if (n->prev != p || p->next != n) {
printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev);
printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev);
printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev);
WARN_ON(1);
}
}
static void plist_check_list(struct list_head *top)
{
struct list_head *prev = top, *next = top->next;
plist_check_prev_next(top, prev, next);
while (next != top) {
prev = next;
next = prev->next;
plist_check_prev_next(top, prev, next);
}
}
static void plist_check_head(struct plist_head *head)
{
WARN_ON(!head->lock);
if (head->lock)
WARN_ON_SMP(!spin_is_locked(head->lock));
plist_check_list(&head->prio_list);
plist_check_list(&head->node_list);
}
#else
# define plist_check_head(h) do { } while (0)
#endif
/**
* plist_add - add @node to @head
*
* @node: &struct plist_node pointer
* @head: &struct plist_head pointer
*/
void plist_add(struct plist_node *node, struct plist_head *head)
{
struct plist_node *iter;
plist_check_head(head);
WARN_ON(!plist_node_empty(node));
list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
if (node->prio < iter->prio)
goto lt_prio;
else if (node->prio == iter->prio) {
iter = list_entry(iter->plist.prio_list.next,
struct plist_node, plist.prio_list);
goto eq_prio;
}
}
lt_prio:
list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
eq_prio:
list_add_tail(&node->plist.node_list, &iter->plist.node_list);
plist_check_head(head);
}
/**
* plist_del - Remove a @node from plist.
*
* @node: &struct plist_node pointer - entry to be removed
* @head: &struct plist_head pointer - list head
*/
void plist_del(struct plist_node *node, struct plist_head *head)
{
plist_check_head(head);
if (!list_empty(&node->plist.prio_list)) {
struct plist_node *next = plist_first(&node->plist);
list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
list_del_init(&node->plist.prio_list);
}
list_del_init(&node->plist.node_list);
plist_check_head(head);
}
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