# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1175089421 -3600
# Node ID c16e258fcac554fb186c80ad2592f215b6843ffb
# Parent 72ea3ff64ad8a7a811d9d1d467a3c7b96a1765bb
xen: Sync the list.h macros to Linux 2.6.18.
This also pulls in RCU-related functions, superceding a patch from Mike Day.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
xen/include/xen/list.h | 704 +++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 629 insertions(+), 75 deletions(-)
diff -r 72ea3ff64ad8 -r c16e258fcac5 xen/include/xen/list.h
--- a/xen/include/xen/list.h Wed Mar 28 14:42:54 2007 +0100
+++ b/xen/include/xen/list.h Wed Mar 28 14:43:41 2007 +0100
@@ -1,13 +1,21 @@
/******************************************************************************
* list.h
*
- * Useful linked-list definitions taken from the Linux kernel.
+ * Useful linked-list definitions taken from the Linux kernel (2.6.18).
*/
#ifndef __XEN_LIST_H__
#define __XEN_LIST_H__
#include <xen/lib.h>
+#include <asm/system.h>
+
+/* These are non-NULL pointers that will result in page faults
+ * under normal circumstances, used to verify that nobody uses
+ * non-initialized list entries.
+ */
+#define LIST_POISON1 ((void *) 0x00100100)
+#define LIST_POISON2 ((void *) 0x00200200)
/*
* Simple doubly linked list implementation.
@@ -28,9 +36,11 @@ struct list_head {
#define LIST_HEAD(name) \
struct list_head name = LIST_HEAD_INIT(name)
-#define INIT_LIST_HEAD(ptr) do { \
- (ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while (0)
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+ list->next = list;
+ list->prev = list;
+}
/*
* Insert a new entry between two known consecutive entries.
@@ -38,9 +48,9 @@ struct list_head {
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
-static inline void __list_add(struct list_head * new,
- struct list_head * prev,
- struct list_head * next)
+static inline void __list_add(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next)
{
next->prev = new;
new->next = next;
@@ -75,14 +85,74 @@ static inline void list_add_tail(struct
}
/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add_rcu(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next)
+{
+ new->next = next;
+ new->prev = prev;
+ smp_wmb();
+ next->prev = new;
+ prev->next = new;
+}
+
+/**
+ * list_add_rcu - add a new entry to rcu-protected list
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as list_add_rcu()
+ * or list_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * list_for_each_entry_rcu().
+ */
+static inline void list_add_rcu(struct list_head *new, struct list_head *head)
+{
+ __list_add_rcu(new, head, head->next);
+}
+
+/**
+ * list_add_tail_rcu - add a new entry to rcu-protected list
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as list_add_tail_rcu()
+ * or list_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * list_for_each_entry_rcu().
+ */
+static inline void list_add_tail_rcu(struct list_head *new,
+ struct list_head *head)
+{
+ __list_add_rcu(new, head->prev, head);
+}
+
+/*
* Delete a list entry by making the prev/next entries
* point to each other.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
-static inline void __list_del(struct list_head * prev,
- struct list_head * next)
+static inline void __list_del(struct list_head *prev,
+ struct list_head *next)
{
next->prev = prev;
prev->next = next;
@@ -99,6 +169,79 @@ static inline void list_del(struct list_
ASSERT(entry->next->prev == entry);
ASSERT(entry->prev->next == entry);
__list_del(entry->prev, entry->next);
+ entry->next = LIST_POISON1;
+ entry->prev = LIST_POISON2;
+}
+
+/**
+ * list_del_rcu - deletes entry from list without re-initialization
+ * @entry: the element to delete from the list.
+ *
+ * Note: list_empty on entry does not return true after this,
+ * the entry is in an undefined state. It is useful for RCU based
+ * lockfree traversal.
+ *
+ * In particular, it means that we can not poison the forward
+ * pointers that may still be used for walking the list.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as list_del_rcu()
+ * or list_add_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * list_for_each_entry_rcu().
+ *
+ * Note that the caller is not permitted to immediately free
+ * the newly deleted entry. Instead, either synchronize_rcu()
+ * or call_rcu() must be used to defer freeing until an RCU
+ * grace period has elapsed.
+ */
+static inline void list_del_rcu(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+ entry->prev = LIST_POISON2;
+}
+
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ * Note: if 'old' was empty, it will be overwritten.
+ */
+static inline void list_replace(struct list_head *old,
+ struct list_head *new)
+{
+ new->next = old->next;
+ new->next->prev = new;
+ new->prev = old->prev;
+ new->prev->next = new;
+}
+
+static inline void list_replace_init(struct list_head *old,
+ struct list_head *new)
+{
+ list_replace(old, new);
+ INIT_LIST_HEAD(old);
+}
+
+/*
+ * list_replace_rcu - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * The old entry will be replaced with the new entry atomically.
+ * Note: 'old' should not be empty.
+ */
+static inline void list_replace_rcu(struct list_head *old,
+ struct list_head *new)
+{
+ new->next = old->next;
+ new->prev = old->prev;
+ smp_wmb();
+ new->next->prev = new;
+ new->prev->next = new;
+ old->prev = LIST_POISON2;
}
/**
@@ -112,12 +255,79 @@ static inline void list_del_init(struct
}
/**
+ * list_move - delete from one list and add as another's head
+ * @list: the entry to move
+ * @head: the head that will precede our entry
+ */
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+ __list_del(list->prev, list->next);
+ list_add(list, head);
+}
+
+/**
+ * list_move_tail - delete from one list and add as another's tail
+ * @list: the entry to move
+ * @head: the head that will follow our entry
+ */
+static inline void list_move_tail(struct list_head *list,
+ struct list_head *head)
+{
+ __list_del(list->prev, list->next);
+ list_add_tail(list, head);
+}
+
+/**
+ * list_is_last - tests whether @list is the last entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_last(const struct list_head *list,
+ const struct list_head *head)
+{
+ return list->next == head;
+}
+
+/**
* list_empty - tests whether a list is empty
* @head: the list to test.
*/
-static inline int list_empty(struct list_head *head)
+static inline int list_empty(const struct list_head *head)
{
return head->next == head;
+}
+
+/**
+ * list_empty_careful - tests whether a list is empty and not being modified
+ * @head: the list to test
+ *
+ * Description:
+ * tests whether a list is empty _and_ checks that no other CPU might be
+ * in the process of modifying either member (next or prev)
+ *
+ * NOTE: using list_empty_careful() without synchronization
+ * can only be safe if the only activity that can happen
+ * to the list entry is list_del_init(). Eg. it cannot be used
+ * if another CPU could re-list_add() it.
+ */
+static inline int list_empty_careful(const struct list_head *head)
+{
+ struct list_head *next = head->next;
+ return (next == head) && (next == head->prev);
+}
+
+static inline void __list_splice(struct list_head *list,
+ struct list_head *head)
+{
+ struct list_head *first = list->next;
+ struct list_head *last = list->prev;
+ struct list_head *at = head->next;
+
+ first->prev = head;
+ head->next = first;
+
+ last->next = at;
+ at->prev = last;
}
/**
@@ -127,18 +337,23 @@ static inline int list_empty(struct list
*/
static inline void list_splice(struct list_head *list, struct list_head *head)
{
- struct list_head *first = list->next;
-
- if ( first != list )
- {
- struct list_head *last = list->prev;
- struct list_head *at = head->next;
-
- first->prev = head;
- head->next = first;
-
- last->next = at;
- at->prev = last;
+ if (!list_empty(list))
+ __list_splice(list, head);
+}
+
+/**
+ * list_splice_init - join two lists and reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_init(struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list)) {
+ __list_splice(list, head);
+ INIT_LIST_HEAD(list);
}
}
@@ -149,64 +364,250 @@ static inline void list_splice(struct li
* @member: the name of the list_struct within the struct.
*/
#define list_entry(ptr, type, member) \
- ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
+ container_of(ptr, type, member)
/**
* list_for_each - iterate over a list
- * @pos: the &struct list_head to use as a loop counter.
+ * @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.
*/
-#define list_for_each(pos, head) \
- for ( pos = (head)->next; pos != (head); pos = pos->next )
-
-/**
- * list_for_each_safe - iterate over a list safe against removal
- * of list entry
- * @pos: the &struct list_head to use as a loop counter.
- * @n: another &struct list_head to use as temporary storage
- * @head: the head for your list.
+#define list_for_each(pos, head) \
+ for (pos = (head)->next; prefetch(pos->next), pos != (head); \
+ pos = pos->next)
+
+/**
+ * __list_for_each - iterate over a list
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ *
+ * This variant differs from list_for_each() in that it's the
+ * simplest possible list iteration code, no prefetching is done.
+ * Use this for code that knows the list to be very short (empty
+ * or 1 entry) most of the time.
+ */
+#define __list_for_each(pos, head) \
+ for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * list_for_each_prev - iterate over a list backwards
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+ for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
+ pos = pos->prev)
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
*/
#define list_for_each_safe(pos, n, head) \
- for ( pos = (head)->next, n = pos->next; pos != (head); \
- pos = n, n = pos->next )
+ for (pos = (head)->next, n = pos->next; pos != (head); \
+ pos = n, n = pos->next)
/**
* list_for_each_backwards_safe - iterate backwards over a list safe
* against removal of list entry
* @pos: the &struct list_head to use as a loop counter.
- * @n: another &struct list_head to use as temporary storage
- * @head: the head for your list.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
*/
#define list_for_each_backwards_safe(pos, n, head) \
for ( pos = (head)->prev, n = pos->prev; pos != (head); \
pos = n, n = pos->prev )
/**
- * list_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.
+ * list_for_each_entry - iterate over list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member) \
- for ( pos = list_entry((head)->next, typeof(*pos), member), \
- prefetch(pos->member.next); \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member), \
- prefetch(pos->member.next) )
+ for (pos = list_entry((head)->next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member) \
+ for (pos = list_entry((head)->prev, typeof(*pos), member); \
+ prefetch(pos->member.prev), &pos->member != (head); \
+ pos = list_entry(pos->member.prev, typeof(*pos), member))
+
+/**
+ * list_prepare_entry - prepare a pos entry for use in
+ * list_for_each_entry_continue
+ * @pos: the type * to use as a start point
+ * @head: the head of the list
+ * @member: the name of the list_struct within the struct.
+ *
+ * Prepares a pos entry for use as a start point in
+ * list_for_each_entry_continue.
+ */
+#define list_prepare_entry(pos, head, member) \
+ ((pos) ? : list_entry(head, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue - continue iteration over list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue(pos, head, member) \
+ for (pos = list_entry(pos->member.next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_from - iterate over list of given type from the
+ * current point
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member) \
+ for (; prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* list_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.
- * @member: the name of the list_struct within the struct.
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_safe(pos, n, head, member) \
- for ( pos = list_entry((head)->next, typeof(*pos), member), \
- n = list_entry(pos->member.next, typeof(*pos), member); \
- &pos->member != (head); \
- pos = n, n = list_entry(n->member.next, typeof(*n), member) )
+ for (pos = list_entry((head)->next, typeof(*pos), member), \
+ n = list_entry(pos->member.next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_continue
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing after current point,
+ * safe against removal of list entry.
+ */
+#define list_for_each_entry_safe_continue(pos, n, head, member) \
+ for (pos = list_entry(pos->member.next, typeof(*pos), member), \
+ n = list_entry(pos->member.next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_from
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type from current point, safe against
+ * removal of list entry.
+ */
+#define list_for_each_entry_safe_from(pos, n, head, member) \
+ for (n = list_entry(pos->member.next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_reverse
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Iterate backwards over list of given type, safe against removal
+ * of list entry.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member) \
+ for (pos = list_entry((head)->prev, typeof(*pos), member), \
+ n = list_entry(pos->member.prev, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = n, n = list_entry(n->member.prev, typeof(*n), member))
+
+/**
+ * list_for_each_rcu - iterate over an rcu-protected list
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define list_for_each_rcu(pos, head) \
+ for (pos = (head)->next; \
+ prefetch(rcu_dereference(pos)->next), pos != (head); \
+ pos = pos->next)
+
+#define __list_for_each_rcu(pos, head) \
+ for (pos = (head)->next; \
+ rcu_dereference(pos) != (head); \
+ pos = pos->next)
+
+/**
+ * list_for_each_safe_rcu
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
+ *
+ * Iterate over an rcu-protected list, safe against removal of list entry.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define list_for_each_safe_rcu(pos, n, head) \
+ for (pos = (head)->next; \
+ n = rcu_dereference(pos)->next, pos != (head); \
+ pos = n)
+
+/**
+ * list_for_each_entry_rcu - iterate over rcu list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define list_for_each_entry_rcu(pos, head, member) \
+ for (pos = list_entry((head)->next, typeof(*pos), member); \
+ prefetch(rcu_dereference(pos)->member.next), \
+ &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_continue_rcu
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ *
+ * Iterate over an rcu-protected list, continuing after current point.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define list_for_each_continue_rcu(pos, head) \
+ for ((pos) = (pos)->next; \
+ prefetch(rcu_dereference((pos))->next), (pos) != (head); \
+ (pos) = (pos)->next)
/*
* Double linked lists with a single pointer list head.
@@ -247,32 +648,110 @@ static inline void __hlist_del(struct hl
struct hlist_node *next = n->next;
struct hlist_node **pprev = n->pprev;
*pprev = next;
- if ( next )
+ if (next)
next->pprev = pprev;
}
static inline void hlist_del(struct hlist_node *n)
{
__hlist_del(n);
+ n->next = LIST_POISON1;
+ n->pprev = LIST_POISON2;
+}
+
+/**
+ * hlist_del_rcu - deletes entry from hash list without re-initialization
+ * @n: the element to delete from the hash list.
+ *
+ * Note: list_unhashed() on entry does not return true after this,
+ * the entry is in an undefined state. It is useful for RCU based
+ * lockfree traversal.
+ *
+ * In particular, it means that we can not poison the forward
+ * pointers that may still be used for walking the hash list.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_add_head_rcu()
+ * or hlist_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_for_each_entry().
+ */
+static inline void hlist_del_rcu(struct hlist_node *n)
+{
+ __hlist_del(n);
+ n->pprev = LIST_POISON2;
}
static inline void hlist_del_init(struct hlist_node *n)
{
- if ( !hlist_unhashed(n) )
- {
+ if (!hlist_unhashed(n)) {
__hlist_del(n);
INIT_HLIST_NODE(n);
}
}
+/*
+ * hlist_replace_rcu - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * The old entry will be replaced with the new entry atomically.
+ */
+static inline void hlist_replace_rcu(struct hlist_node *old,
+ struct hlist_node *new)
+{
+ struct hlist_node *next = old->next;
+
+ new->next = next;
+ new->pprev = old->pprev;
+ smp_wmb();
+ if (next)
+ new->next->pprev = &new->next;
+ *new->pprev = new;
+ old->pprev = LIST_POISON2;
+}
+
static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
{
struct hlist_node *first = h->first;
n->next = first;
- if ( first )
+ if (first)
first->pprev = &n->next;
h->first = n;
n->pprev = &h->first;
+}
+
+/**
+ * hlist_add_head_rcu
+ * @n: the element to add to the hash list.
+ * @h: the list to add to.
+ *
+ * Description:
+ * Adds the specified element to the specified hlist,
+ * while permitting racing traversals.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_add_head_rcu()
+ * or hlist_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_for_each_entry_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs. Regardless of the type of CPU, the
+ * list-traversal primitive must be guarded by rcu_read_lock().
+ */
+static inline void hlist_add_head_rcu(struct hlist_node *n,
+ struct hlist_head *h)
+{
+ struct hlist_node *first = h->first;
+ n->next = first;
+ n->pprev = &h->first;
+ smp_wmb();
+ if (first)
+ first->pprev = &n->next;
+ h->first = n;
}
/* next must be != NULL */
@@ -292,8 +771,65 @@ static inline void hlist_add_after(struc
n->next = next;
next->pprev = &n->next;
- if ( next->next )
+ if(next->next)
next->next->pprev = &next->next;
+}
+
+/**
+ * hlist_add_before_rcu
+ * @n: the new element to add to the hash list.
+ * @next: the existing element to add the new element before.
+ *
+ * Description:
+ * Adds the specified element to the specified hlist
+ * before the specified node while permitting racing traversals.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_add_head_rcu()
+ * or hlist_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_for_each_entry_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs.
+ */
+static inline void hlist_add_before_rcu(struct hlist_node *n,
+ struct hlist_node *next)
+{
+ n->pprev = next->pprev;
+ n->next = next;
+ smp_wmb();
+ next->pprev = &n->next;
+ *(n->pprev) = n;
+}
+
+/**
+ * hlist_add_after_rcu
+ * @prev: the existing element to add the new element after.
+ * @n: the new element to add to the hash list.
+ *
+ * Description:
+ * Adds the specified element to the specified hlist
+ * after the specified node while permitting racing traversals.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_add_head_rcu()
+ * or hlist_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_for_each_entry_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs.
+ */
+static inline void hlist_add_after_rcu(struct hlist_node *prev,
+ struct hlist_node *n)
+{
+ n->next = prev->next;
+ n->pprev = &prev->next;
+ smp_wmb();
+ prev->next = n;
+ if (n->next)
+ n->next->pprev = &n->next;
}
#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
@@ -303,8 +839,8 @@ static inline void hlist_add_after(struc
pos = pos->next)
#define hlist_for_each_safe(pos, n, head) \
- for ( pos = (head)->first; pos && ({ n = pos->next; 1; }); \
- pos = n )
+ for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
+ pos = n)
/**
* hlist_for_each_entry - iterate over list of given type
@@ -314,10 +850,10 @@ static inline void hlist_add_after(struc
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry(tpos, pos, head, member) \
- for ( pos = (head)->first; \
- pos && ({ prefetch(pos->next); 1;}) && \
- ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
- pos = pos->next )
+ for (pos = (head)->first; \
+ pos && ({ prefetch(pos->next); 1;}) && \
+ ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+ pos = pos->next)
/**
* hlist_for_each_entry_continue - iterate over a hlist continuing
@@ -327,10 +863,10 @@ static inline void hlist_add_after(struc
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_continue(tpos, pos, member) \
- for ( pos = (pos)->next; \
- pos && ({ prefetch(pos->next); 1;}) && \
- ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
- pos = pos->next )
+ for (pos = (pos)->next; \
+ pos && ({ prefetch(pos->next); 1;}) && \
+ ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+ pos = pos->next)
/**
* hlist_for_each_entry_from - iterate over a hlist continuing from
@@ -340,9 +876,9 @@ static inline void hlist_add_after(struc
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_from(tpos, pos, member) \
- for ( ; pos && ({ prefetch(pos->next); 1;}) && \
- ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
- pos = pos->next )
+ for (; pos && ({ prefetch(pos->next); 1;}) && \
+ ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+ pos = pos->next)
/**
* hlist_for_each_entry_safe - iterate over list of given type safe
@@ -354,10 +890,28 @@ static inline void hlist_add_after(struc
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
- for ( pos = (head)->first; \
- pos && ({ n = pos->next; 1; }) && \
+ for (pos = (head)->first; \
+ pos && ({ n = pos->next; 1; }) && \
+ ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+ pos = n)
+
+
+/**
+ * hlist_for_each_entry_rcu - iterate over rcu list of given type
+ * @tpos: the type * to use as a loop cursor.
+ * @pos: the &struct hlist_node to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the hlist_node within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define hlist_for_each_entry_rcu(tpos, pos, head, member) \
+ for (pos = (head)->first; \
+ rcu_dereference(pos) && ({ prefetch(pos->next); 1;}) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
- pos = n )
+ pos = pos->next)
#endif /* __XEN_LIST_H__ */
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