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Merge branch 'tip/futex/devel' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-rt into core/futexes 

futex,plist: Pass the real head of the priority list to plist_del()
 futex,plist: Remove debug lock assignment from plist_node
 plist: Shrink struct plist_head
 plist: Add priority list test
This commit is contained in:
Thomas Gleixner 2011-03-12 11:37:14 +01:00
parent 8d7718aa08 6d55da53db
commit 995612178c
3 changed files with 162 additions and 60 deletions
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47
include/linux/plist.h
View File

@ -31,15 +31,17 @@
*
* 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|<------------------------------------|
* pl:prio_list (only for plist_node)
* nl:node_list
* HEAD| NODE(S)
* |
* ||------------------------------------|
* ||->|pl|<->|pl|<--------------->|pl|<-|
* | |10| |21| |21| |21| |40| (prio)
* | | | | | | | | | | |
* | | | | | | | | | | |
* |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
* |-------------------------------------------|
*
* The nodes on the prio_list list are sorted by priority to simplify
* the insertion of new nodes. There are no nodes with duplicate
@ -78,7 +80,6 @@
#include <linux/spinlock_types.h>
struct plist_head {
struct list_head prio_list;
struct list_head node_list;
#ifdef CONFIG_DEBUG_PI_LIST
raw_spinlock_t *rawlock;
@ -88,7 +89,8 @@ struct plist_head {
struct plist_node {
int prio;
struct plist_head plist;
struct list_head prio_list;
struct list_head node_list;
};
#ifdef CONFIG_DEBUG_PI_LIST
@ -100,7 +102,6 @@ struct plist_node {
#endif
#define _PLIST_HEAD_INIT(head) \
.prio_list = LIST_HEAD_INIT((head).prio_list), \
.node_list = LIST_HEAD_INIT((head).node_list)
/**
@ -133,7 +134,8 @@ struct plist_node {
#define PLIST_NODE_INIT(node, __prio) \
{ \
.prio = (__prio), \
.plist = { _PLIST_HEAD_INIT((node).plist) }, \
.prio_list = LIST_HEAD_INIT((node).prio_list), \
.node_list = LIST_HEAD_INIT((node).node_list), \
}
/**
@ -144,7 +146,6 @@ struct plist_node {
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->spinlock = lock;
@ -160,7 +161,6 @@ plist_head_init(struct plist_head *head, spinlock_t *lock)
static inline void
plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
{
INIT_LIST_HEAD(&head->prio_list);
INIT_LIST_HEAD(&head->node_list);
#ifdef CONFIG_DEBUG_PI_LIST
head->rawlock = lock;
@ -176,7 +176,8 @@ plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
static inline void plist_node_init(struct plist_node *node, int prio)
{
node->prio = prio;
plist_head_init(&node->plist, NULL);
INIT_LIST_HEAD(&node->prio_list);
INIT_LIST_HEAD(&node->node_list);
}
extern void plist_add(struct plist_node *node, struct plist_head *head);
@ -188,7 +189,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head);
* @head: the head for your list
*/
#define plist_for_each(pos, head) \
list_for_each_entry(pos, &(head)->node_list, plist.node_list)
list_for_each_entry(pos, &(head)->node_list, node_list)
/**
* plist_for_each_safe - iterate safely over a plist of given type
@ -199,7 +200,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head);
* Iterate over a plist of given type, safe against removal of list entry.
*/
#define plist_for_each_safe(pos, n, head) \
list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)
list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)
/**
* plist_for_each_entry - iterate over list of given type
@ -208,7 +209,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head);
* @mem: 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)
list_for_each_entry(pos, &(head)->node_list, mem.node_list)
/**
* plist_for_each_entry_safe - iterate safely over list of given type
@ -220,7 +221,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head);
* Iterate over list of given type, safe against removal of list entry.
*/
#define plist_for_each_entry_safe(pos, n, head, m) \
list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)
list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list)
/**
* plist_head_empty - return !0 if a plist_head is empty
@ -237,7 +238,7 @@ static inline int plist_head_empty(const struct plist_head *head)
*/
static inline int plist_node_empty(const struct plist_node *node)
{
return plist_head_empty(&node->plist);
return list_empty(&node->node_list);
}
/* All functions below assume the plist_head is not empty. */
@ -285,7 +286,7 @@ static inline int plist_node_empty(const struct plist_node *node)
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);
struct plist_node, node_list);
}
/**
@ -297,7 +298,7 @@ static inline struct plist_node *plist_first(const struct plist_head *head)
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);
struct plist_node, node_list);
}
#endif

40
kernel/futex.c
View File

@ -772,6 +772,24 @@ retry:
return ret;
}
/**
* __unqueue_futex() - Remove the futex_q from its futex_hash_bucket
* @q: The futex_q to unqueue
*
* The q->lock_ptr must not be NULL and must be held by the caller.
*/
static void __unqueue_futex(struct futex_q *q)
{
struct futex_hash_bucket *hb;
if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr)
|| plist_node_empty(&q->list)))
return;
hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock);
plist_del(&q->list, &hb->chain);
}
/*
* The hash bucket lock must be held when this is called.
* Afterwards, the futex_q must not be accessed.
@ -789,7 +807,7 @@ static void wake_futex(struct futex_q *q)
*/
get_task_struct(p);
plist_del(&q->list, &q->list.plist);
__unqueue_futex(q);
/*
* The waiting task can free the futex_q as soon as
* q->lock_ptr = NULL is written, without taking any locks. A
@ -1064,9 +1082,6 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
plist_del(&q->list, &hb1->chain);
plist_add(&q->list, &hb2->chain);
q->lock_ptr = &hb2->lock;
#ifdef CONFIG_DEBUG_PI_LIST
q->list.plist.spinlock = &hb2->lock;
#endif
}
get_futex_key_refs(key2);
q->key = *key2;
@ -1093,16 +1108,12 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
get_futex_key_refs(key);
q->key = *key;
WARN_ON(plist_node_empty(&q->list));
plist_del(&q->list, &q->list.plist);
__unqueue_futex(q);
WARN_ON(!q->rt_waiter);
q->rt_waiter = NULL;
q->lock_ptr = &hb->lock;
#ifdef CONFIG_DEBUG_PI_LIST
q->list.plist.spinlock = &hb->lock;
#endif
wake_up_state(q->task, TASK_NORMAL);
}
@ -1450,9 +1461,6 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
prio = min(current->normal_prio, MAX_RT_PRIO);
plist_node_init(&q->list, prio);
#ifdef CONFIG_DEBUG_PI_LIST
q->list.plist.spinlock = &hb->lock;
#endif
plist_add(&q->list, &hb->chain);
q->task = current;
spin_unlock(&hb->lock);
@ -1497,8 +1505,7 @@ retry:
spin_unlock(lock_ptr);
goto retry;
}
WARN_ON(plist_node_empty(&q->list));
plist_del(&q->list, &q->list.plist);
__unqueue_futex(q);
BUG_ON(q->pi_state);
@ -1518,8 +1525,7 @@ retry:
static void unqueue_me_pi(struct futex_q *q)
__releases(q->lock_ptr)
{
WARN_ON(plist_node_empty(&q->list));
plist_del(&q->list, &q->list.plist);
__unqueue_futex(q);
BUG_ON(!q->pi_state);
free_pi_state(q->pi_state);
@ -2156,7 +2162,7 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
* We were woken prior to requeue by a timeout or a signal.
* Unqueue the futex_q and determine which it was.
*/
plist_del(&q->list, &q->list.plist);
plist_del(&q->list, &hb->chain);
/* Handle spurious wakeups gracefully */
ret = -EWOULDBLOCK;

135
lib/plist.c
View File

@ -28,6 +28,8 @@
#ifdef CONFIG_DEBUG_PI_LIST
static struct plist_head test_head;
static void plist_check_prev_next(struct list_head *t, struct list_head *p,
struct list_head *n)
{
@ -54,12 +56,13 @@ static void plist_check_list(struct list_head *top)
static void plist_check_head(struct plist_head *head)
{
WARN_ON(!head->rawlock && !head->spinlock);
WARN_ON(head != &test_head && !head->rawlock && !head->spinlock);
if (head->rawlock)
WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
if (head->spinlock)
WARN_ON_SMP(!spin_is_locked(head->spinlock));
plist_check_list(&head->prio_list);
if (!plist_head_empty(head))
plist_check_list(&plist_first(head)->prio_list);
plist_check_list(&head->node_list);
}
@ -75,25 +78,33 @@ static void plist_check_head(struct plist_head *head)
*/
void plist_add(struct plist_node *node, struct plist_head *head)
{
struct plist_node *iter;
struct plist_node *first, *iter, *prev = NULL;
struct list_head *node_next = &head->node_list;
plist_check_head(head);
WARN_ON(!plist_node_empty(node));
WARN_ON(!list_empty(&node->prio_list));
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;
if (plist_head_empty(head))
goto ins_node;
first = iter = plist_first(head);
do {
if (node->prio < iter->prio) {
node_next = &iter->node_list;
break;
}
}
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);
prev = iter;
iter = list_entry(iter->prio_list.next,
struct plist_node, prio_list);
} while (iter != first);
if (!prev || prev->prio != node->prio)
list_add_tail(&node->prio_list, &iter->prio_list);
ins_node:
list_add_tail(&node->node_list, node_next);
plist_check_head(head);
}
@ -108,14 +119,98 @@ 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);
if (!list_empty(&node->prio_list)) {
if (node->node_list.next != &head->node_list) {
struct plist_node *next;
list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
list_del_init(&node->plist.prio_list);
next = list_entry(node->node_list.next,
struct plist_node, node_list);
/* add the next plist_node into prio_list */
if (list_empty(&next->prio_list))
list_add(&next->prio_list, &node->prio_list);
}
list_del_init(&node->prio_list);
}
list_del_init(&node->plist.node_list);
list_del_init(&node->node_list);
plist_check_head(head);
}
#ifdef CONFIG_DEBUG_PI_LIST
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/init.h>
static struct plist_node __initdata test_node[241];
static void __init plist_test_check(int nr_expect)
{
struct plist_node *first, *prio_pos, *node_pos;
if (plist_head_empty(&test_head)) {
BUG_ON(nr_expect != 0);
return;
}
prio_pos = first = plist_first(&test_head);
plist_for_each(node_pos, &test_head) {
if (nr_expect-- < 0)
break;
if (node_pos == first)
continue;
if (node_pos->prio == prio_pos->prio) {
BUG_ON(!list_empty(&node_pos->prio_list));
continue;
}
BUG_ON(prio_pos->prio > node_pos->prio);
BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
prio_pos = node_pos;
}
BUG_ON(nr_expect != 0);
BUG_ON(prio_pos->prio_list.next != &first->prio_list);
}
static int __init plist_test(void)
{
int nr_expect = 0, i, loop;
unsigned int r = local_clock();
printk(KERN_INFO "start plist test\n");
plist_head_init(&test_head, NULL);
for (i = 0; i < ARRAY_SIZE(test_node); i++)
plist_node_init(test_node + i, 0);
for (loop = 0; loop < 1000; loop++) {
r = r * 193939 % 47629;
i = r % ARRAY_SIZE(test_node);
if (plist_node_empty(test_node + i)) {
r = r * 193939 % 47629;
test_node[i].prio = r % 99;
plist_add(test_node + i, &test_head);
nr_expect++;
} else {
plist_del(test_node + i, &test_head);
nr_expect--;
}
plist_test_check(nr_expect);
}
for (i = 0; i < ARRAY_SIZE(test_node); i++) {
if (plist_node_empty(test_node + i))
continue;
plist_del(test_node + i, &test_head);
nr_expect--;
plist_test_check(nr_expect);
}
printk(KERN_INFO "end plist test\n");
return 0;
}
module_init(plist_test);
#endif