futex,plist: updates

LKML-Reference: <[email protected]>

---
 kernel/futex.c |   31 +++++++++++++++++++++++--------
 1 files changed, 23 insertions(+), 8 deletions(-)

kernel/futex.c +23 -8

index b766d28..6feeea4 100644
@@ -775,6 +775,24 @@ 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.

@@ -792,7 +810,7 @@ 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

@@ -1100,8 +1118,7 @@ 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;

@@ -1504,8 +1521,7 @@ 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);

@@ -1525,8 +1541,7 @@ 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);

@@ -2167,7 +2182,7 @@ 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;

Signature · 1 line

1.7.2.3

Steven Rostedt

author

2011-03-12 03:19 UTC #2 lore raw

PATCH 2/4 futex,plist: Remove debug lock assignment from plist_node

From: Lai Jiangshan <[email protected]>

The original code uses &plist_node->plist as the fake head of the priority list for plist_del(), these debug locks in the fake head are needed for CONFIG_DEBUG_PI_LIST.

But now we always pass the real head to plist_del(), the debug locks in plist_node will not be used, so we remove these assignments.

Acked-by Darren Hart <[email protected]>

LKML-Reference: <[email protected]>

---
 kernel/futex.c |    9 ---------
 1 files changed, 0 insertions(+), 9 deletions(-)

kernel/futex.c +0 -9

index 6feeea4..9fe9131 100644
@@ -1089,9 +1089,6 @@ 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;

@@ -1124,9 +1121,6 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 	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);
 }

@@ -1474,9 +1468,6 @@ 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);

Signature · 1 line

1.7.2.3

Steven Rostedt

author

2011-03-12 03:19 UTC #3 lore raw

PATCH 3/4 plist: Shrink struct plist_head

From: Lai Jiangshan <[email protected]>

struct plist_head is used in struct task_struct as well as struct rtmutex. If we can make it smaller, it will also make these structures smaller as well.

The field prio_list in struct plist_head is seldom used and we can get its information from the plist_nodes. Removing this field will decrease the size of plist_head by half.

LKML-Reference: <[email protected]>

---
 include/linux/plist.h |   47 +++++++++++++++++++++--------------------
 lib/plist.c           |   54 +++++++++++++++++++++++++++++++-----------------
 2 files changed, 59 insertions(+), 42 deletions(-)

include/linux/plist.h +24 ~~-23~~

index 7254eda..c9b9f32 100644
@@ -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

lib/plist.c +35 ~~-19~~

81 lines not on this page · raw message

Signature · 1 line

1.7.2.3

Steven Rostedt

author

2011-03-12 03:19 UTC #4 lore raw

PATCH 4/4 plist: Add priority list test

From: Lai Jiangshan <[email protected]>

Add test code for checking plist when the kernel is booting.

LKML-Reference: <[email protected]>

---
 lib/plist.c |   81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 80 insertions(+), 1 deletions(-)

lib/plist.c +80 -1

index 8c614d0..0ae7e64 100644
@@ -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)
 {

@@ -54,7 +56,7 @@ 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)

@@ -135,3 +137,80 @@ void plist_del(struct plist_node *node, struct plist_head *head)
 
 	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

Signature · 1 line

1.7.2.3

Steven Rostedt

author

2011-03-12 03:23 UTC #5 lore raw