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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/include/linux/rculist.h
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/include/linux/rculist.h')
-rw-r--r--kernel/include/linux/rculist.h556
1 files changed, 556 insertions, 0 deletions
diff --git a/kernel/include/linux/rculist.h b/kernel/include/linux/rculist.h
new file mode 100644
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+++ b/kernel/include/linux/rculist.h
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+#ifndef _LINUX_RCULIST_H
+#define _LINUX_RCULIST_H
+
+#ifdef __KERNEL__
+
+/*
+ * RCU-protected list version
+ */
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+
+/*
+ * Why is there no list_empty_rcu()? Because list_empty() serves this
+ * purpose. The list_empty() function fetches the RCU-protected pointer
+ * and compares it to the address of the list head, but neither dereferences
+ * this pointer itself nor provides this pointer to the caller. Therefore,
+ * it is not necessary to use rcu_dereference(), so that list_empty() can
+ * be used anywhere you would want to use a list_empty_rcu().
+ */
+
+/*
+ * INIT_LIST_HEAD_RCU - Initialize a list_head visible to RCU readers
+ * @list: list to be initialized
+ *
+ * You should instead use INIT_LIST_HEAD() for normal initialization and
+ * cleanup tasks, when readers have no access to the list being initialized.
+ * However, if the list being initialized is visible to readers, you
+ * need to keep the compiler from being too mischievous.
+ */
+static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
+{
+ ACCESS_ONCE(list->next) = list;
+ ACCESS_ONCE(list->prev) = list;
+}
+
+/*
+ * return the ->next pointer of a list_head in an rcu safe
+ * way, we must not access it directly
+ */
+#define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next)))
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+#ifndef CONFIG_DEBUG_LIST
+static inline void __list_add_rcu(struct list_head *new,
+ struct list_head *prev, struct list_head *next)
+{
+ new->next = next;
+ new->prev = prev;
+ rcu_assign_pointer(list_next_rcu(prev), new);
+ next->prev = new;
+}
+#else
+void __list_add_rcu(struct list_head *new,
+ struct list_head *prev, struct list_head *next);
+#endif
+
+/**
+ * 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.
+ *
+ * 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(entry);
+ entry->prev = LIST_POISON2;
+}
+
+/**
+ * hlist_del_init_rcu - deletes entry from hash list with re-initialization
+ * @n: the element to delete from the hash list.
+ *
+ * Note: list_unhashed() on the node return true after this. It is
+ * useful for RCU based read lockfree traversal if the writer side
+ * must know if the list entry is still hashed or already unhashed.
+ *
+ * In particular, it means that we can not poison the forward pointers
+ * that may still be used for walking the hash list and we can only
+ * zero the pprev pointer so list_unhashed() will return true after
+ * this.
+ *
+ * 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().
+ */
+static inline void hlist_del_init_rcu(struct hlist_node *n)
+{
+ if (!hlist_unhashed(n)) {
+ __hlist_del(n);
+ n->pprev = NULL;
+ }
+}
+
+/**
+ * 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;
+ rcu_assign_pointer(list_next_rcu(new->prev), new);
+ new->next->prev = new;
+ old->prev = LIST_POISON2;
+}
+
+/**
+ * list_splice_init_rcu - splice an RCU-protected list into an existing list.
+ * @list: the RCU-protected list to splice
+ * @head: the place in the list to splice the first list into
+ * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
+ *
+ * @head can be RCU-read traversed concurrently with this function.
+ *
+ * Note that this function blocks.
+ *
+ * Important note: the caller must take whatever action is necessary to
+ * prevent any other updates to @head. In principle, it is possible
+ * to modify the list as soon as sync() begins execution.
+ * If this sort of thing becomes necessary, an alternative version
+ * based on call_rcu() could be created. But only if -really-
+ * needed -- there is no shortage of RCU API members.
+ */
+static inline void list_splice_init_rcu(struct list_head *list,
+ struct list_head *head,
+ void (*sync)(void))
+{
+ struct list_head *first = list->next;
+ struct list_head *last = list->prev;
+ struct list_head *at = head->next;
+
+ if (list_empty(list))
+ return;
+
+ /*
+ * "first" and "last" tracking list, so initialize it. RCU readers
+ * have access to this list, so we must use INIT_LIST_HEAD_RCU()
+ * instead of INIT_LIST_HEAD().
+ */
+
+ INIT_LIST_HEAD_RCU(list);
+
+ /*
+ * At this point, the list body still points to the source list.
+ * Wait for any readers to finish using the list before splicing
+ * the list body into the new list. Any new readers will see
+ * an empty list.
+ */
+
+ sync();
+
+ /*
+ * Readers are finished with the source list, so perform splice.
+ * The order is important if the new list is global and accessible
+ * to concurrent RCU readers. Note that RCU readers are not
+ * permitted to traverse the prev pointers without excluding
+ * this function.
+ */
+
+ last->next = at;
+ rcu_assign_pointer(list_next_rcu(head), first);
+ first->prev = head;
+ at->prev = last;
+}
+
+/**
+ * list_entry_rcu - get the struct for this entry
+ * @ptr: the &struct list_head pointer.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_entry_rcu(ptr, type, member) \
+({ \
+ typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
+ container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
+})
+
+/**
+ * Where are list_empty_rcu() and list_first_entry_rcu()?
+ *
+ * Implementing those functions following their counterparts list_empty() and
+ * list_first_entry() is not advisable because they lead to subtle race
+ * conditions as the following snippet shows:
+ *
+ * if (!list_empty_rcu(mylist)) {
+ * struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member);
+ * do_something(bar);
+ * }
+ *
+ * The list may not be empty when list_empty_rcu checks it, but it may be when
+ * list_first_entry_rcu rereads the ->next pointer.
+ *
+ * Rereading the ->next pointer is not a problem for list_empty() and
+ * list_first_entry() because they would be protected by a lock that blocks
+ * writers.
+ *
+ * See list_first_or_null_rcu for an alternative.
+ */
+
+/**
+ * list_first_or_null_rcu - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_first_or_null_rcu(ptr, type, member) \
+({ \
+ struct list_head *__ptr = (ptr); \
+ struct list_head *__next = ACCESS_ONCE(__ptr->next); \
+ likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \
+})
+
+/**
+ * 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_head 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_rcu((head)->next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue_rcu - 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_head within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_rcu(pos, head, member) \
+ for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
+
+/**
+ * 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;
+}
+
+/**
+ * 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;
+ rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);
+ if (next)
+ new->next->pprev = &new->next;
+ old->pprev = LIST_POISON2;
+}
+
+/*
+ * return the first or the next element in an RCU protected hlist
+ */
+#define hlist_first_rcu(head) (*((struct hlist_node __rcu **)(&(head)->first)))
+#define hlist_next_rcu(node) (*((struct hlist_node __rcu **)(&(node)->next)))
+#define hlist_pprev_rcu(node) (*((struct hlist_node __rcu **)((node)->pprev)))
+
+/**
+ * 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;
+ rcu_assign_pointer(hlist_first_rcu(h), n);
+ if (first)
+ first->pprev = &n->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;
+ rcu_assign_pointer(hlist_pprev_rcu(n), n);
+ next->pprev = &n->next;
+}
+
+/**
+ * hlist_add_behind_rcu
+ * @n: the new element to add to the hash list.
+ * @prev: the existing element to add the new element after.
+ *
+ * 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_behind_rcu(struct hlist_node *n,
+ struct hlist_node *prev)
+{
+ n->next = prev->next;
+ n->pprev = &prev->next;
+ rcu_assign_pointer(hlist_next_rcu(prev), n);
+ if (n->next)
+ n->next->pprev = &n->next;
+}
+
+#define __hlist_for_each_rcu(pos, head) \
+ for (pos = rcu_dereference(hlist_first_rcu(head)); \
+ pos; \
+ pos = rcu_dereference(hlist_next_rcu(pos)))
+
+/**
+ * hlist_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 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(pos, head, member) \
+ for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\
+ typeof(*(pos)), member); \
+ pos; \
+ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
+ &(pos)->member)), typeof(*(pos)), member))
+
+/**
+ * hlist_for_each_entry_rcu_notrace - iterate over rcu list of given type (for tracing)
+ * @pos: the type * 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().
+ *
+ * This is the same as hlist_for_each_entry_rcu() except that it does
+ * not do any RCU debugging or tracing.
+ */
+#define hlist_for_each_entry_rcu_notrace(pos, head, member) \
+ for (pos = hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\
+ typeof(*(pos)), member); \
+ pos; \
+ pos = hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\
+ &(pos)->member)), typeof(*(pos)), member))
+
+/**
+ * hlist_for_each_entry_rcu_bh - 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 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_bh(pos, head, member) \
+ for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_first_rcu(head)),\
+ typeof(*(pos)), member); \
+ pos; \
+ pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(\
+ &(pos)->member)), typeof(*(pos)), member))
+
+/**
+ * hlist_for_each_entry_continue_rcu - iterate over a hlist continuing after current point
+ * @pos: the type * to use as a loop cursor.
+ * @member: the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_continue_rcu(pos, member) \
+ for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
+ pos; \
+ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
+
+/**
+ * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
+ * @pos: the type * to use as a loop cursor.
+ * @member: the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_continue_rcu_bh(pos, member) \
+ for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
+ pos; \
+ pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
+
+/**
+ * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
+ * @pos: the type * to use as a loop cursor.
+ * @member: the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_from_rcu(pos, member) \
+ for (; pos; \
+ pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
+ typeof(*(pos)), member))
+
+#endif /* __KERNEL__ */
+#endif