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authorEdward Cree <ecree@solarflare.com>2018-07-02 18:13:40 +0300
committerDavid S. Miller <davem@davemloft.net>2018-07-04 08:06:19 +0300
commit4ce0017a373afaaa9ef17614d8fa4f6fde261d18 (patch)
treea5d8c2c03598cafdf3afb2aa997d7e177511bfc1 /include/linux/list.h
parent7da517a3bc529dc5399e742688b32cafa2ca5ca0 (diff)
downloadlinux-4ce0017a373afaaa9ef17614d8fa4f6fde261d18.tar.xz
net: core: another layer of lists, around PF_MEMALLOC skb handling
First example of a layer splitting the list (rather than merely taking individual packets off it). Involves new list.h function, list_cut_before(), like list_cut_position() but cuts on the other side of the given entry. Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/list.h')
-rw-r--r--include/linux/list.h30
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/list.h b/include/linux/list.h
index 4b129df4d46b..de04cc5ed536 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -285,6 +285,36 @@ static inline void list_cut_position(struct list_head *list,
__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)