From: Alexander Aring <aahringo@redhat.com>
To: teigland@redhat.com
Cc: cluster-devel@redhat.com
Subject: [Cluster-devel] [PATCH dlm-tool 3/3] dlm_controld: update list implementation
Date: Mon, 21 Aug 2023 12:25:40 -0400 [thread overview]
Message-ID: <20230821162540.594227-3-aahringo@redhat.com> (raw)
In-Reply-To: <20230821162540.594227-1-aahringo@redhat.com>
This patch updates the list implementation taken from the Linux kernel.
There are new list manipulation functions introduced that could be
became useful later.
---
dlm_controld/linux_helpers.h | 7 +
dlm_controld/list.h | 667 ++++++++++++++++++++++++++++++-----
2 files changed, 576 insertions(+), 98 deletions(-)
diff --git a/dlm_controld/linux_helpers.h b/dlm_controld/linux_helpers.h
index 09705cff..f959cf55 100644
--- a/dlm_controld/linux_helpers.h
+++ b/dlm_controld/linux_helpers.h
@@ -24,6 +24,11 @@
#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+#define POISON_POINTER_DELTA 0xdeadbeef
+
+#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
+#define LIST_POISON2 ((void *) 0x122 + POISON_POINTER_DELTA)
+
/**
* container_of - cast a member of a structure out to the containing structure
* @ptr: the pointer to the member.
@@ -39,6 +44,8 @@
"pointer type mismatch in container_of()"); \
((type *)(__mptr - offsetof(type, member))); })
+#define READ_ONCE(x) (*(const volatile typeof(x) *)&(x))
+
#define WRITE_ONCE(x, val) \
do { \
*(volatile typeof(x) *)&(x) = (val); \
diff --git a/dlm_controld/list.h b/dlm_controld/list.h
index e9df2ef2..aab3b2b0 100644
--- a/dlm_controld/list.h
+++ b/dlm_controld/list.h
@@ -1,20 +1,17 @@
-/* Copied from include/linux/list.h */
-
+/* Copied from include/linux/list.h */
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
+#include <stdbool.h>
+
#include "linux_helpers.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)
+struct list_head {
+ struct list_head *next, *prev;
+};
/*
- * Simple doubly linked list implementation.
+ * Circular doubly linked list implementation.
*
* Some of the internal functions ("__xxx") are useful when
* manipulating whole lists rather than single entries, as
@@ -23,21 +20,44 @@
* using the generic single-entry routines.
*/
-struct list_head {
- struct list_head *next, *prev;
-};
-
#define LIST_HEAD_INIT(name) { &(name), &(name) }
#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)
+/**
+ * INIT_LIST_HEAD - Initialize a list_head structure
+ * @list: list_head structure to be initialized.
+ *
+ * Initializes the list_head to point to itself. If it is a list header,
+ * the result is an empty list.
+ */
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+ WRITE_ONCE(list->next, list);
+ WRITE_ONCE(list->prev, list);
+}
+
+#ifdef CONFIG_DEBUG_LIST
+extern bool __list_add_valid(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next);
+extern bool __list_del_entry_valid(struct list_head *entry);
+#else
+static inline bool __list_add_valid(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next)
+{
+ return true;
+}
+static inline bool __list_del_entry_valid(struct list_head *entry)
+{
+ return true;
+}
+#endif
/*
- * Insert a new entry between two known consecutive entries.
+ * Insert a new entry between two known consecutive entries.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
@@ -46,10 +66,13 @@ static inline void __list_add(struct list_head *new,
struct list_head *prev,
struct list_head *next)
{
+ if (!__list_add_valid(new, prev, next))
+ return;
+
next->prev = new;
new->next = next;
new->prev = prev;
- prev->next = new;
+ WRITE_ONCE(prev->next, new);
}
/**
@@ -65,6 +88,7 @@ static inline void list_add(struct list_head *new, struct list_head *head)
__list_add(new, head, head->next);
}
+
/**
* list_add_tail - add a new entry
* @new: new entry to be added
@@ -88,30 +112,99 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head)
static inline void __list_del(struct list_head * prev, struct list_head * next)
{
next->prev = prev;
- prev->next = next;
+ WRITE_ONCE(prev->next, next);
+}
+
+/*
+ * Delete a list entry and clear the 'prev' pointer.
+ *
+ * This is a special-purpose list clearing method used in the networking code
+ * for lists allocated as per-cpu, where we don't want to incur the extra
+ * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this
+ * needs to check the node 'prev' pointer instead of calling list_empty().
+ */
+static inline void __list_del_clearprev(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+ entry->prev = NULL;
+}
+
+static inline void __list_del_entry(struct list_head *entry)
+{
+ if (!__list_del_entry_valid(entry))
+ return;
+
+ __list_del(entry->prev, entry->next);
}
/**
* list_del - deletes entry from list.
* @entry: the element to delete from the list.
- * Note: list_empty on entry does not return true after this, the entry is
+ * Note: list_empty() on entry does not return true after this, the entry is
* in an undefined state.
*/
static inline void list_del(struct list_head *entry)
{
- __list_del(entry->prev, entry->next);
+ __list_del_entry(entry);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * 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;
+}
+
+/**
+ * list_replace_init - replace old entry by new one and initialize the old one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
+static inline void list_replace_init(struct list_head *old,
+ struct list_head *new)
+{
+ list_replace(old, new);
+ INIT_LIST_HEAD(old);
+}
+
+/**
+ * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position
+ * @entry1: the location to place entry2
+ * @entry2: the location to place entry1
+ */
+static inline void list_swap(struct list_head *entry1,
+ struct list_head *entry2)
+{
+ struct list_head *pos = entry2->prev;
+
+ list_del(entry2);
+ list_replace(entry1, entry2);
+ if (pos == entry1)
+ pos = entry2;
+ list_add(entry1, pos);
+}
+
/**
* list_del_init - deletes entry from list and reinitialize it.
* @entry: the element to delete from the list.
*/
static inline void list_del_init(struct list_head *entry)
{
- __list_del(entry->prev, entry->next);
- INIT_LIST_HEAD(entry);
+ __list_del_entry(entry);
+ INIT_LIST_HEAD(entry);
}
/**
@@ -121,8 +214,8 @@ static inline void list_del_init(struct list_head *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_del_entry(list);
+ list_add(list, head);
}
/**
@@ -133,8 +226,61 @@ static inline void list_move(struct list_head *list, struct list_head *head)
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_del_entry(list);
+ list_add_tail(list, head);
+}
+
+/**
+ * list_bulk_move_tail - move a subsection of a list to its tail
+ * @head: the head that will follow our entry
+ * @first: first entry to move
+ * @last: last entry to move, can be the same as first
+ *
+ * Move all entries between @first and including @last before @head.
+ * All three entries must belong to the same linked list.
+ */
+static inline void list_bulk_move_tail(struct list_head *head,
+ struct list_head *first,
+ struct list_head *last)
+{
+ first->prev->next = last->next;
+ last->next->prev = first->prev;
+
+ head->prev->next = first;
+ first->prev = head->prev;
+
+ last->next = head;
+ head->prev = last;
+}
+
+/**
+ * list_is_first -- tests whether @list is the first entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_first(const struct list_head *list, const struct list_head *head)
+{
+ return list->prev == 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_is_head - tests whether @list is the list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_head(const struct list_head *list, const struct list_head *head)
+{
+ return list == head;
}
/**
@@ -143,50 +289,155 @@ static inline void list_move_tail(struct list_head *list,
*/
static inline int list_empty(const struct list_head *head)
{
- return head->next == head;
+ return READ_ONCE(head->next) == head;
}
/**
- * list_empty_careful - tests whether a list is
- * empty _and_ checks that no other CPU might be
- * in the process of still modifying either member
- *
- * 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.
+ * list_rotate_left - rotate the list to the left
+ * @head: the head of the list
+ */
+static inline void list_rotate_left(struct list_head *head)
+{
+ struct list_head *first;
+
+ if (!list_empty(head)) {
+ first = head->next;
+ list_move_tail(first, head);
+ }
+}
+
+/**
+ * list_rotate_to_front() - Rotate list to specific item.
+ * @list: The desired new front of the list.
+ * @head: The head of the list.
*
+ * Rotates list so that @list becomes the new front of the list.
+ */
+static inline void list_rotate_to_front(struct list_head *list,
+ struct list_head *head)
+{
+ /*
+ * Deletes the list head from the list denoted by @head and
+ * places it as the tail of @list, this effectively rotates the
+ * list so that @list is at the front.
+ */
+ list_move_tail(head, list);
+}
+
+/**
+ * list_is_singular - tests whether a list has just one entry.
* @head: the list to test.
*/
-static inline int list_empty_careful(const struct list_head *head)
+static inline int list_is_singular(const struct list_head *head)
{
- struct list_head *next = head->next;
- return (next == head) && (next == head->prev);
+ return !list_empty(head) && (head->next == head->prev);
}
-static inline void __list_splice(struct list_head *list,
- struct list_head *head)
+static inline void __list_cut_position(struct list_head *list,
+ struct list_head *head, struct list_head *entry)
+{
+ struct list_head *new_first = entry->next;
+ list->next = head->next;
+ list->next->prev = list;
+ list->prev = entry;
+ entry->next = list;
+ head->next = new_first;
+ new_first->prev = head;
+}
+
+/**
+ * list_cut_position - cut a list into two
+ * @list: a new list to add all removed entries
+ * @head: a list with entries
+ * @entry: an entry within head, could be the head itself
+ * and if so we won't cut the list
+ *
+ * This helper moves the initial part of @head, up to and
+ * including @entry, from @head to @list. You should
+ * pass on @entry an element you know is on @head. @list
+ * should be an empty list or a list you do not care about
+ * losing its data.
+ *
+ */
+static inline void list_cut_position(struct list_head *list,
+ struct list_head *head, struct list_head *entry)
+{
+ if (list_empty(head))
+ return;
+ if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next))
+ return;
+ if (list_is_head(entry, head))
+ INIT_LIST_HEAD(list);
+ else
+ __list_cut_position(list, head, entry);
+}
+
+/**
+ * list_cut_before - cut a list into two, before given entry
+ * @list: a new list to add all removed entries
+ * @head: a list with entries
+ * @entry: an entry within head, could be the head itself
+ *
+ * This helper moves the initial part of @head, up to but
+ * excluding @entry, from @head to @list. You should pass
+ * in @entry an element you know is on @head. @list should
+ * be an empty list or a list you do not care about losing
+ * its data.
+ * If @entry == @head, all entries on @head are moved to
+ * @list.
+ */
+static inline void list_cut_before(struct list_head *list,
+ struct list_head *head,
+ struct list_head *entry)
+{
+ if (head->next == entry) {
+ INIT_LIST_HEAD(list);
+ return;
+ }
+ list->next = head->next;
+ list->next->prev = list;
+ list->prev = entry->prev;
+ list->prev->next = list;
+ head->next = entry;
+ entry->prev = head;
+}
+
+static inline void __list_splice(const struct list_head *list,
+ struct list_head *prev,
+ struct list_head *next)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
- struct list_head *at = head->next;
- first->prev = head;
- head->next = first;
+ first->prev = prev;
+ prev->next = first;
- last->next = at;
- at->prev = last;
+ last->next = next;
+ next->prev = last;
+}
+
+/**
+ * list_splice - join two lists, this is designed for stacks
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice(const struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list))
+ __list_splice(list, head, head->next);
}
/**
- * list_splice - join two lists
+ * list_splice_tail - join two lists, each list being a queue
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
-static inline void list_splice(struct list_head *list, struct list_head *head)
+static inline void list_splice_tail(struct list_head *list,
+ struct list_head *head)
{
if (!list_empty(list))
- __list_splice(list, head);
+ __list_splice(list, head->prev, head);
}
/**
@@ -200,7 +451,24 @@ static inline void list_splice_init(struct list_head *list,
struct list_head *head)
{
if (!list_empty(list)) {
- __list_splice(list, head);
+ __list_splice(list, head, head->next);
+ INIT_LIST_HEAD(list);
+ }
+}
+
+/**
+ * list_splice_tail_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.
+ *
+ * Each of the lists is a queue.
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_tail_init(struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list)) {
+ __list_splice(list, head->prev, head);
INIT_LIST_HEAD(list);
}
}
@@ -209,117 +477,320 @@ static inline void list_splice_init(struct list_head *list,
* list_entry - 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_struct within the struct.
+ * @member: the name of the list_head within the struct.
*/
#define list_entry(ptr, type, member) \
container_of(ptr, type, member)
/**
* list_first_entry - 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_struct within the struct.
+ * @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 list is expected to be not empty.
*/
#define list_first_entry(ptr, type, member) \
list_entry((ptr)->next, type, member)
+/**
+ * list_last_entry - get the last 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 list is expected to be not empty.
+ */
+#define list_last_entry(ptr, type, member) \
+ list_entry((ptr)->prev, type, member)
+
+/**
+ * list_first_entry_or_null - 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.
+ */
+#define list_first_entry_or_null(ptr, type, member) ({ \
+ struct list_head *head__ = (ptr); \
+ struct list_head *pos__ = READ_ONCE(head__->next); \
+ pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
+
+/**
+ * list_next_entry - get the next element in list
+ * @pos: the type * to cursor
+ * @member: the name of the list_head within the struct.
+ */
+#define list_next_entry(pos, member) \
+ list_entry((pos)->member.next, typeof(*(pos)), member)
+
+/**
+ * list_next_entry_circular - get the next element in list
+ * @pos: the type * to cursor.
+ * @head: the list head to take the element from.
+ * @member: the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the last element (return the first element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_next_entry_circular(pos, head, member) \
+ (list_is_last(&(pos)->member, head) ? \
+ list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))
+
+/**
+ * list_prev_entry - get the prev element in list
+ * @pos: the type * to cursor
+ * @member: the name of the list_head within the struct.
+ */
+#define list_prev_entry(pos, member) \
+ list_entry((pos)->member.prev, typeof(*(pos)), member)
+
+/**
+ * list_prev_entry_circular - get the prev element in list
+ * @pos: the type * to cursor.
+ * @head: the list head to take the element from.
+ * @member: the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the first element (return the last element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_prev_entry_circular(pos, head, member) \
+ (list_is_first(&(pos)->member, head) ? \
+ list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, 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)
+ for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
/**
- * __list_for_each - iterate over a list
- * @pos: the &struct list_head to use as a loop counter.
+ * list_for_each_continue - continue iteration 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.
+ * Continue to iterate over a list, continuing after the current position.
*/
-#define __list_for_each(pos, head) \
- for (pos = (head)->next; pos != (head); pos = pos->next)
+#define list_for_each_continue(pos, head) \
+ for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next)
/**
* list_for_each_prev - iterate over a list backwards
- * @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_prev(pos, head) \
- for (pos = (head)->prev; pos != (head); pos = pos->prev)
-
+ for (pos = (head)->prev; !list_is_head(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 counter.
+ * 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; \
+ !list_is_head(pos, (head)); \
+ pos = n, n = pos->next)
+
+/**
+ * list_for_each_prev_safe - iterate over a list backwards 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_prev_safe(pos, n, head) \
+ for (pos = (head)->prev, n = pos->prev; \
+ !list_is_head(pos, (head)); \
+ pos = n, n = pos->prev)
+
+/**
+ * list_count_nodes - count nodes in the list
+ * @head: the head for your list.
+ */
+static inline size_t list_count_nodes(struct list_head *head)
+{
+ struct list_head *pos;
+ size_t count = 0;
+
+ list_for_each(pos, head)
+ count++;
+
+ return count;
+}
+
+/**
+ * list_entry_is_head - test if the entry points to the head of the list
+ * @pos: the type * to cursor
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_entry_is_head(pos, head, member) \
+ (&pos->member == (head))
/**
* list_for_each_entry - iterate over list of given type
- * @pos: the type * to use as a loop counter.
+ * @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.
+ * @member: the name of the list_head within the struct.
*/
#define list_for_each_entry(pos, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member); \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member))
+ for (pos = list_first_entry(head, typeof(*pos), member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = list_next_entry(pos, member))
/**
* list_for_each_entry_reverse - iterate backwards over list of given type.
- * @pos: the type * to use as a loop counter.
+ * @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.
+ * @member: the name of the list_head within the struct.
*/
#define list_for_each_entry_reverse(pos, head, member) \
- for (pos = list_entry((head)->prev, typeof(*pos), member); \
- &pos->member != (head); \
- pos = list_entry(pos->member.prev, typeof(*pos), member))
+ for (pos = list_last_entry(head, typeof(*pos), member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = list_prev_entry(pos, member))
/**
- * list_prepare_entry - prepare a pos entry for use as a start point in
- * list_for_each_entry_continue
+ * 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.
+ * @member: the name of the list_head 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 - iterate over list of given type
- * continuing after existing point
- * @pos: the type * to use as a loop counter.
+ * 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.
+ * @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(pos, head, member) \
- for (pos = list_entry(pos->member.next, typeof(*pos), member); \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member))
+ for (pos = list_next_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_continue_reverse - iterate backwards from the given point
+ * @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.
+ *
+ * Start to iterate over list of given type backwards, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_reverse(pos, head, member) \
+ for (pos = list_prev_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = list_prev_entry(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_head within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member) \
+ for (; !list_entry_is_head(pos, head, member); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_from_reverse - iterate backwards 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_head within the struct.
+ *
+ * Iterate backwards over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from_reverse(pos, head, member) \
+ for (; !list_entry_is_head(pos, head, member); \
+ pos = list_prev_entry(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.
+ * @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.
+ * @member: the name of the list_head 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_first_entry(head, typeof(*pos), member), \
+ n = list_next_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_continue - continue list iteration safe against removal
+ * @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_head 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_next_entry(pos, member), \
+ n = list_next_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = n, n = list_next_entry(n, member))
+/**
+ * list_for_each_entry_safe_from - iterate over list from current point safe against removal
+ * @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_head 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_next_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
+ * @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_head 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_last_entry(head, typeof(*pos), member), \
+ n = list_prev_entry(pos, member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = n, n = list_prev_entry(n, member))
+
+/**
+ * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
+ * @pos: the loop cursor used in the list_for_each_entry_safe loop
+ * @n: temporary storage used in list_for_each_entry_safe
+ * @member: the name of the list_head within the struct.
+ *
+ * list_safe_reset_next is not safe to use in general if the list may be
+ * modified concurrently (eg. the lock is dropped in the loop body). An
+ * exception to this is if the cursor element (pos) is pinned in the list,
+ * and list_safe_reset_next is called after re-taking the lock and before
+ * completing the current iteration of the loop body.
+ */
+#define list_safe_reset_next(pos, n, member) \
+ n = list_next_entry(pos, member)
#endif
--
2.31.1
prev parent reply other threads:[~2023-08-21 16:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-21 16:25 [Cluster-devel] [PATCH dlm-tool 1/3] dlm_controld: update rbtree implementation Alexander Aring
2023-08-21 16:25 ` [Cluster-devel] [PATCH dlm-tool 2/3] dlm_controld: update container_of() implementation Alexander Aring
2023-08-21 16:25 ` Alexander Aring [this message]
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