--- /dev/null
+#ifndef _KCOMPAT_RCULIST_H
+#define _KCOMPAT_RCULIST_H
+
+/*
+ * RCU-protected list version
+ *
+ * 2002-10-18 19:01:25-07:00, dipankar@in.ibm.com
+ * [PATCH] RCU helper patchset 2/2
+ *
+ * This adds a set of list macros that make handling of list protected
+ * by RCU simpler. The interfaces added are -
+ *
+ * list_add_rcu
+ * list_add_tail_rcu
+ * - Adds an element by taking care of memory barrier (wmb()).
+ *
+ * list_del_rcu
+ * - Deletes an element but doesn't re-initialize the pointers in
+ * the element for supporting RCU based traversal.
+ *
+ * list_for_each_rcu
+ * __list_for_each_rcu
+ * - Traversal of RCU protected list - takes care of memory barriers
+ * transparently.
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <urcu.h>
+#include <kcompat/list.h>
+
+/*
+ * 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);
+}
+
+/**
+ * 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.
+ *
+ * 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_kernel()
+ * 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);
+}
+
+/**
+ * list_for_each_rcu - iterate over an rcu-protected list
+ * @pos: the &struct list_head to use as a loop counter.
+ * @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 = rcu_dereference((head)->next); \
+ prefetch(pos->next), pos != (head); \
+ pos = rcu_dereference(pos->next))
+
+#define __list_for_each_rcu(pos, head) \
+ for (pos = rcu_dereference((head)->next); \
+ pos != (head); \
+ pos = rcu_dereference(pos->next))
+
+/**
+ * list_for_each_entry_rcu - iterate over a rcu-protected list
+ * @pos: the struct type pointer to use as a loop counter
+ * @head: the head for your list
+ * @member: the name of the struct list_head element in your struct type
+ *
+ * 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(rcu_dereference((head)->next), typeof(*pos), \
+ member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(rcu_dereference(pos->member.next),typeof(*pos), \
+ member))
+
+#endif /* _KCOMPAT_RCULIST_H */
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